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{gamma}-Hydroxybutyrate does not mediate glucose inhibition of glucagon secretion [Signal Transduction]

Hypersecretion of glucagon from pancreatic α-cells strongly contributes to diabetic hyperglycemia. Moreover, failure of α-cells to increase glucagon secretion in response to falling blood glucose concentrations compromises the defense against hypoglycemia, a common complication in diabetes therapy. However, the mechanisms underlying glucose regulation of glucagon secretion are poorly understood and likely involve both α-cell–intrinsic and intraislet paracrine signaling. Among paracrine factors, glucose-stimulated release of the GABA metabolite γ-hydroxybutyric acid (GHB) from pancreatic β-cells might mediate glucose suppression of glucagon release via GHB receptors on α-cells. However, the direct effects of GHB on α-cell signaling and glucagon release have not been investigated. Here, we found that GHB (4–10 μm) lacked effects on the cytoplasmic concentrations of the secretion-regulating messengers Ca2+ and cAMP in mouse α-cells. Glucagon secretion from perifused mouse islets was also unaffected by GHB at both 1 and 7 mm glucose. The GHB receptor agonist 3-chloropropanoic acid and the antagonist NCS-382 had no effects on glucagon secretion and did not affect stimulation of secretion induced by a drop in glucose from 7 to 1 mm. Inhibition of endogenous GHB formation with the GABA transaminase inhibitor vigabatrin also failed to influence glucagon secretion at 1 mm glucose and did not prevent the suppressive effect of 7 mm glucose. In human islets, GHB tended to stimulate glucagon secretion at 1 mm glucose, an effect mimicked by 3-chloropropanoic acid. We conclude that GHB does not mediate the inhibitory effect of glucose on glucagon secretion.




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12-LOX catalyzes the oxidation of 2-arachidonoyl-lysolipids in platelets generating eicosanoid-lysolipids that are attenuated by iPLA2{gamma} knockout [Signal Transduction]

The canonical pathway of eicosanoid production in most mammalian cells is initiated by phospholipase A2-mediated release of arachidonic acid, followed by its enzymatic oxidation resulting in a vast array of eicosanoid products. However, recent work has demonstrated that the major phospholipase in mitochondria, iPLA2γ (patatin-like phospholipase domain containing 8 (PNPLA8)), possesses sn-1 specificity, with polyunsaturated fatty acids at the sn-2 position generating polyunsaturated sn-2-acyl lysophospholipids. Through strategic chemical derivatization, chiral chromatographic separation, and multistage tandem MS, here we first demonstrate that human platelet-type 12-lipoxygenase (12-LOX) can directly catalyze the regioselective and stereospecific oxidation of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) and 2-arachidonoyl-lysophosphatidylethanolamine (2-AA-LPE). Next, we identified these two eicosanoid-lysophospholipids in murine myocardium and in isolated platelets. Moreover, we observed robust increases in 2-AA-LPC, 2-AA-LPE, and their downstream 12-LOX oxidation products, 12(S)-HETE-LPC and 12(S)-HETE-LPE, in calcium ionophore (A23187)-stimulated murine platelets. Mechanistically, genetic ablation of iPLA2γ markedly decreased the calcium-stimulated production of 2-AA-LPC, 2-AA-LPE, and 12-HETE-lysophospholipids in mouse platelets. Importantly, a potent and selective 12-LOX inhibitor, ML355, significantly inhibited the production of 12-HETE-LPC and 12-HETE-LPE in activated platelets. Furthermore, we found that aging is accompanied by significant changes in 12-HETE-LPC in murine serum that were also markedly attenuated by iPLA2γ genetic ablation. Collectively, these results identify previously unknown iPLA2γ-initiated signaling pathways mediated by direct 12-LOX oxidation of 2-AA-LPC and 2-AA-LPE. This oxidation generates previously unrecognized eicosanoid-lysophospholipids that may serve as biomarkers for age-related diseases and could potentially be used as targets in therapeutic interventions.




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Cross-regulation between LUBAC and caspase-1 modulates cell death and inflammation [Signal Transduction]

The linear ubiquitin assembly complex (LUBAC) is an essential component of the innate and adaptive immune system. Modification of cellular substrates with linear polyubiquitin chains is a key regulatory step in signal transduction that impacts cell death and inflammatory signaling downstream of various innate immunity receptors. Loss-of-function mutations in the LUBAC components HOIP and HOIL-1 yield a systemic autoinflammatory disease in humans, whereas their genetic ablation is embryonically lethal in mice. Deficiency of the LUBAC adaptor protein Sharpin results in a multi-organ inflammatory disease in mice characterized by chronic proliferative dermatitis (cpdm), which is propagated by TNFR1-induced and RIPK1-mediated keratinocyte cell death. We have previously shown that caspase-1 and -11 promoted the dermatitis pathology of cpdm mice and mediated cell death in the skin. Here, we describe a reciprocal regulation of caspase-1 and LUBAC activities in keratinocytes. We show that LUBAC interacted with caspase-1 via HOIP and modified its CARD domain with linear polyubiquitin and that depletion of HOIP or Sharpin resulted in heightened caspase-1 activation and cell death in response to inflammasome activation, unlike what is observed in macrophages. Reciprocally, caspase-1, as well as caspase-8, regulated LUBAC activity by proteolytically processing HOIP at Asp-348 and Asp-387 during the execution of cell death. HOIP processing impeded substrate ubiquitination in the NF-κB pathway and resulted in enhanced apoptosis. These results highlight a regulatory mechanism underlying efficient apoptosis in keratinocytes and provide further evidence of a cross-talk between inflammatory and cell death pathways.




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Heterotrimeric Gq proteins as therapeutic targets? [Molecular Bases of Disease]

Heterotrimeric G proteins are the core upstream elements that transduce and amplify the cellular signals from G protein–coupled receptors (GPCRs) to intracellular effectors. GPCRs are the largest family of membrane proteins encoded in the human genome and are the targets of about one-third of prescription medicines. However, to date, no single therapeutic agent exerts its effects via perturbing heterotrimeric G protein function, despite a plethora of evidence linking G protein malfunction to human disease. Several recent studies have brought to light that the Gq family–specific inhibitor FR900359 (FR) is unexpectedly efficacious in silencing the signaling of Gq oncoproteins, mutant Gq variants that mostly exist in the active state. These data not only raise the hope that researchers working in drug discovery may be able to potentially strike Gq oncoproteins from the list of undruggable targets, but also raise questions as to how FR achieves its therapeutic effect. Here, we place emphasis on these recent studies and explain why they expand our pharmacological armamentarium for targeting Gq protein oncogenes as well as broaden our mechanistic understanding of Gq protein oncogene function. We also highlight how this novel insight impacts the significance and utility of using G(q) proteins as targets in drug discovery efforts.




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ABC transporters control ATP release through cholesterol-dependent volume-regulated anion channel activity [Signal Transduction]

Purinergic signaling by extracellular ATP regulates a variety of cellular events and is implicated in both normal physiology and pathophysiology. Several molecules have been associated with the release of ATP and other small molecules, but their precise contributions have been difficult to assess because of their complexity and heterogeneity. Here, we report on the results of a gain-of-function screen for modulators of hypotonicity-induced ATP release using HEK-293 cells and murine cerebellar granule neurons, along with bioluminescence, calcium FLIPR, and short hairpin RNA–based gene-silencing assays. This screen utilized the most extensive genome-wide ORF collection to date, covering 90% of human, nonredundant, protein-encoding genes. We identified two ABCG1 (ABC subfamily G member 1) variants, which regulate cellular cholesterol, as modulators of hypotonicity-induced ATP release. We found that cholesterol levels control volume-regulated anion channel–dependent ATP release. These findings reveal novel mechanisms for the regulation of ATP release and volume-regulated anion channel activity and provide critical links among cellular status, cholesterol, and purinergic signaling.




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Noncatalytic Bruton's tyrosine kinase activates PLC{gamma}2 variants mediating ibrutinib resistance in human chronic lymphocytic leukemia cells [Membrane Biology]

Treatment of patients with chronic lymphocytic leukemia (CLL) with inhibitors of Bruton's tyrosine kinase (BTK), such as ibrutinib, is limited by primary or secondary resistance to this drug. Examinations of CLL patients with late relapses while on ibrutinib, which inhibits BTK's catalytic activity, revealed several mutations in BTK, most frequently resulting in the C481S substitution, and disclosed many mutations in PLCG2, encoding phospholipase C-γ2 (PLCγ2). The PLCγ2 variants typically do not exhibit constitutive activity in cell-free systems, leading to the suggestion that in intact cells they are hypersensitive to Rac family small GTPases or to the upstream kinases spleen-associated tyrosine kinase (SYK) and Lck/Yes-related novel tyrosine kinase (LYN). The sensitivity of the PLCγ2 variants to BTK itself has remained unknown. Here, using genetically-modified DT40 B lymphocytes, along with various biochemical assays, including analysis of PLCγ2-mediated inositol phosphate formation, inositol phospholipid assessments, fluorescence recovery after photobleaching (FRAP) static laser microscopy, and determination of intracellular calcium ([Ca2+]i), we show that various CLL-specific PLCγ2 variants such as PLCγ2S707Y are hyper-responsive to activated BTK, even in the absence of BTK's catalytic activity and independently of enhanced PLCγ2 phospholipid substrate supply. At high levels of B-cell receptor (BCR) activation, which may occur in individual CLL patients, catalytically-inactive BTK restored the ability of the BCR to mediate increases in [Ca2+]i. Because catalytically-inactive BTK is insensitive to active-site BTK inhibitors, the mechanism involving the noncatalytic BTK uncovered here may contribute to preexisting reduced sensitivity or even primary resistance of CLL to these drugs.




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Reduction of protein phosphatase 2A (PP2A) complexity reveals cellular functions and dephosphorylation motifs of the PP2A/B'{delta} holoenzyme [Enzymology]

Protein phosphatase 2A (PP2A) is a large enzyme family responsible for most cellular Ser/Thr dephosphorylation events. PP2A substrate specificity, localization, and regulation by second messengers rely on more than a dozen regulatory subunits (including B/R2, B'/R5, and B″/R3), which form the PP2A heterotrimeric holoenzyme by associating with a dimer comprising scaffolding (A) and catalytic (C) subunits. Because of partial redundancy and high endogenous expression of PP2A holoenzymes, traditional approaches of overexpressing, knocking down, or knocking out PP2A regulatory subunits have yielded only limited insights into their biological roles and substrates. To this end, here we sought to reduce the complexity of cellular PP2A holoenzymes. We used tetracycline-inducible expression of pairs of scaffolding and regulatory subunits with complementary charge-reversal substitutions in their interaction interfaces. For each of the three regulatory subunit families, we engineered A/B charge–swap variants that could bind to one another, but not to endogenous A and B subunits. Because endogenous Aα was targeted by a co-induced shRNA, endogenous B subunits were rapidly degraded, resulting in expression of predominantly a single PP2A heterotrimer composed of the A/B charge–swap pair and the endogenous catalytic subunit. Using B'δ/PPP2R5D, we show that PP2A complexity reduction, but not PP2A overexpression, reveals a role of this holoenzyme in suppression of extracellular signal–regulated kinase signaling and protein kinase A substrate dephosphorylation. When combined with global phosphoproteomics, the PP2A/B'δ reduction approach identified consensus dephosphorylation motifs in its substrates and suggested that residues surrounding the phosphorylation site play roles in PP2A substrate specificity.




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G{alpha}q splice variants mediate phototransduction, rhodopsin synthesis, and retinal integrity in Drosophila [Signal Transduction]

Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis.




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NF-{kappa}B mediates lipopolysaccharide-induced alternative pre-mRNA splicing of MyD88 in mouse macrophages [Signal Transduction]

Although a robust inflammatory response is needed to combat infection, this response must ultimately be terminated to prevent chronic inflammation. One mechanism that terminates inflammatory signaling is the production of alternative mRNA splice forms in the Toll-like receptor (TLR) signaling pathway. Whereas most genes in the TLR pathway encode positive mediators of inflammatory signaling, several, including that encoding the MyD88 signaling adaptor, also produce alternative spliced mRNA isoforms that encode dominant-negative inhibitors of the response. Production of these negatively acting alternatively spliced isoforms is induced by stimulation with the TLR4 agonist lipopolysaccharide (LPS); thus, this alternative pre-mRNA splicing represents a negative feedback loop that terminates TLR signaling and prevents chronic inflammation. In the current study, we investigated the mechanisms regulating the LPS-induced alternative pre-mRNA splicing of the MyD88 transcript in murine macrophages. We found that 1) the induction of the alternatively spliced MyD88 form is due to alternative pre-mRNA splicing and not caused by another RNA regulatory mechanism, 2) MyD88 splicing is regulated by both the MyD88- and TRIF-dependent arms of the TLR signaling pathway, 3) MyD88 splicing is regulated by the NF-κB transcription factor, and 4) NF-κB likely regulates MyD88 alternative pre-mRNA splicing per se rather than regulating splicing indirectly by altering MyD88 transcription. We conclude that alternative splicing of MyD88 may provide a sensitive mechanism that ensures robust termination of inflammation for tissue repair and restoration of normal tissue homeostasis once an infection is controlled.




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Biophysical characterization of SARAH domain-mediated multimerization of Hippo pathway complexes in Drosophila [Signal Transduction]

Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity.




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Mechanistic insights explain the transforming potential of the T507K substitution in the protein-tyrosine phosphatase SHP2 [Signal Transduction]

The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity.




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DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels [Cell Biology]

Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7−/− mice. Although palmitoylation of barttin in kidneys of Zdhhc7−/− animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7−/− mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.




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The focal adhesion protein kindlin-2 controls mitotic spindle assembly by inhibiting histone deacetylase 6 and maintaining {alpha}-tubulin acetylation [Signal Transduction]

Kindlins are focal adhesion proteins that regulate integrin activation and outside-in signaling. The kindlin family consists of three members, kindlin-1, -2, and -3. Kindlin-2 is widely expressed in multiple cell types, except those from the hematopoietic lineage. A previous study has reported that the Drosophila Fit1 protein (an ortholog of kindlin-2) prevents abnormal spindle assembly; however, the mechanism remains unknown. Here, we show that kindlin-2 maintains spindle integrity in mitotic human cells. The human neuroblastoma SH-SY5Y cell line expresses only kindlin-2, and we found that when SH-SY5Y cells are depleted of kindlin-2, they exhibit pronounced spindle abnormalities and delayed mitosis. Of note, acetylation of α-tubulin, which maintains microtubule flexibility and stability, was diminished in the kindlin-2–depleted cells. Mechanistically, we found that kindlin-2 maintains α-tubulin acetylation by inhibiting the microtubule-associated deacetylase histone deacetylase 6 (HDAC6) via a signaling pathway involving AKT Ser/Thr kinase (AKT)/glycogen synthase kinase 3β (GSK3β) or paxillin. We also provide evidence that prolonged hypoxia down-regulates kindlin-2 expression, leading to spindle abnormalities not only in the SH-SY5Y cell line, but also cell lines derived from colon and breast tissues. The findings of our study highlight that kindlin-2 regulates mitotic spindle assembly and that this process is perturbed in cancer cells in a hypoxic environment.




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Polarization of protease-activated receptor 2 (PAR-2) signaling is altered during airway epithelial remodeling and deciliation [Immunology]

Protease-activated receptor 2 (PAR-2) is activated by secreted proteases from immune cells or fungi. PAR-2 is normally expressed basolaterally in differentiated nasal ciliated cells. We hypothesized that epithelial remodeling during diseases characterized by cilial loss and squamous metaplasia may alter PAR-2 polarization. Here, using a fluorescent arrestin assay, we confirmed that the common fungal airway pathogen Aspergillus fumigatus activates heterologously-expressed PAR-2. Endogenous PAR-2 activation in submerged airway RPMI 2650 or NCI–H520 squamous cells increased intracellular calcium levels and granulocyte macrophage–colony-stimulating factor, tumor necrosis factor α, and interleukin (IL)-6 secretion. RPMI 2650 cells cultured at an air–liquid interface (ALI) responded to apically or basolaterally applied PAR-2 agonists. However, well-differentiated primary nasal epithelial ALIs responded only to basolateral PAR-2 stimulation, indicated by calcium elevation, increased cilia beat frequency, and increased fluid and cytokine secretion. We exposed primary cells to disease-related modifiers that alter epithelial morphology, including IL-13, cigarette smoke condensate, and retinoic acid deficiency, at concentrations and times that altered epithelial morphology without causing breakdown of the epithelial barrier to model early disease states. These altered primary cultures responded to both apical and basolateral PAR-2 stimulation. Imaging nasal polyps and control middle turbinate explants, we found that nasal polyps, but not turbinates, exhibit apical calcium responses to PAR-2 stimulation. However, isolated ciliated cells from both polyps and turbinates maintained basolateral PAR-2 polarization, suggesting that the calcium responses originated from nonciliated cells. Altered PAR-2 polarization in disease-remodeled epithelia may enhance apical responses and increase sensitivity to inhaled proteases.




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Small-molecule agonists of the RET receptor tyrosine kinase activate biased trophic signals that are influenced by the presence of GFRa1 co-receptors [Neurobiology]

Glial cell line–derived neurotrophic factor (GDNF) is a growth factor that regulates the health and function of neurons and other cells. GDNF binds to GDNF family receptor α1 (GFRa1), and the resulting complex activates the RET receptor tyrosine kinase and subsequent downstream signals. This feature restricts GDNF activity to systems in which GFRa1 and RET are both present, a scenario that may constrain GDNF breadth of action. Furthermore, this co-dependence precludes the use of GDNF as a tool to study a putative functional cross-talk between GFRa1 and RET. Here, using biochemical techniques, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and immunohistochemistry in murine cells, tissues, or retinal organotypic cultures, we report that a naphthoquinone/quinolinedione family of small molecules (Q compounds) acts as RET agonists. We found that, like GDNF, signaling through the parental compound Q121 is GFRa1-dependent. Structural modifications of Q121 generated analogs that activated RET irrespective of GFRa1 expression. We used these analogs to examine RET–GFRa1 interactions and show that GFRa1 can influence RET-mediated signaling and enhance or diminish AKT Ser/Thr kinase or extracellular signal-regulated kinase signaling in a biased manner. In a genetic mutant model of retinitis pigmentosa, a lead compound, Q525, afforded sustained RET activation and prevented photoreceptor neuron loss in the retina. This work uncovers key components of the dynamic relationships between RET and its GFRa co-receptor and provides RET agonist scaffolds for drug development.




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Phosphoproteomic characterization of the signaling network resulting from activation of the chemokine receptor CCR2 [Genomics and Proteomics]

Leukocyte recruitment is a universal feature of tissue inflammation and regulated by the interactions of chemokines with their G protein–coupled receptors. Activation of CC chemokine receptor 2 (CCR2) by its cognate chemokine ligands, including CC chemokine ligand 2 (CCL2), plays a central role in recruitment of monocytes in several inflammatory diseases. In this study, we used phosphoproteomics to conduct an unbiased characterization of the signaling network resulting from CCL2 activation of CCR2. Using data-independent acquisition MS analysis, we quantified both the proteome and phosphoproteome in FlpIn-HEK293T cells stably expressing CCR2 at six time points after activation with CCL2. Differential expression analysis identified 699 significantly regulated phosphorylation sites on 441 proteins. As expected, many of these proteins are known to participate in canonical signal transduction pathways and in the regulation of actin cytoskeleton dynamics, including numerous guanine nucleotide exchange factors and GTPase-activating proteins. Moreover, we identified regulated phosphorylation sites in numerous proteins that function in the nucleus, including several constituents of the nuclear pore complex. The results of this study provide an unprecedented level of detail of CCR2 signaling and identify potential targets for regulation of CCR2 function.




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Inflammatory and mitogenic signals drive interleukin 23 subunit alpha (IL23A) secretion independent of IL12B in intestinal epithelial cells [Signal Transduction]

The heterodimeric cytokine interleukin-23 (IL-23 or IL23A/IL12B) is produced by dendritic cells and macrophages and promotes the proinflammatory and regenerative activities of T helper 17 (Th17) and innate lymphoid cells. A recent study has reported that IL-23 is also secreted by lung adenoma cells and generates an inflammatory and immune-suppressed stroma. Here, we observed that proinflammatory tumor necrosis factor (TNF)/NF-κB and mitogen-activated protein kinase (MAPK) signaling strongly induce IL23A expression in intestinal epithelial cells. Moreover, we identified a strong crosstalk between the NF-κB and MAPK/ERK kinase (MEK) pathways, involving the formation of a transcriptional enhancer complex consisting of proto-oncogene c-Jun (c-Jun), RELA proto-oncogene NF-κB subunit (RelA), RUNX family transcription factor 1 (RUNX1), and RUNX3. Collectively, these proteins induced IL23A secretion, confirmed by immunoprecipitation of endogenous IL23A from activated human colorectal cancer (CRC) cell culture supernatants. Interestingly, IL23A was likely secreted in a noncanonical form, as it was not detected by an ELISA specific for heterodimeric IL-23 likely because IL12B expression is absent in CRC cells. Given recent evidence that IL23A promotes tumor formation, we evaluated the efficacy of MAPK/NF-κB inhibitors in attenuating IL23A expression and found that the MEK inhibitor trametinib and BAY 11–7082 (an IKKα/IκB inhibitor) effectively inhibited IL23A in a subset of human CRC lines with mutant KRAS or BRAFV600E mutations. Together, these results indicate that proinflammatory and mitogenic signals dynamically regulate IL23A in epithelial cells. They further reveal its secretion in a noncanonical form independent of IL12B and that small-molecule inhibitors can attenuate IL23A secretion.




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Five Foreign Policy Questions for the UK’s Next Prime Minister

18 June 2019

Thomas Raines

Director, Europe Programme
Even if most don’t get to vote in the Conservative leadership election, the public deserves serious answers on the foreign policy plans of those who want to lead the country.

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10 Downing Street. Photo: Getty Images.

In a month’s time, the UK will have a new prime minister. The campaign has been dominated by candidates’ views on how to deliver Britain’s withdrawal from the EU by October, alongside some discussion of domestic issues.

But relatively little has been said about international affairs, despite the fact that foreign policy questions are becoming a more partisan issue and Britain is facing crucial questions around Brexit and the wider international context. These will be waiting for whoever finds themselves in Number 10 on 22 July. 

1. How can Britain influence Europe from outside the EU?

Theresa May was fond of saying that Britain is leaving the EU but not leaving Europe. Britain cannot change its geography. It will continue to share many strategic and security interests with the rest of the continent, but it will be outside of Europe’s central political and economic project. A new PM will not only have to negotiate Britain’s new relationship with the EU, but also think about how to influence it as a third country.

An aspect of this will be finding a new way to work with the EU on foreign, security and defence policy that meets the need for autonomy on both sides. How deep this relationship is or how institutionalized it will be is yet to be negotiated and can be shaped by the next PM.

The UK needs to decide how ambitiously it wants to engage with the new defence agenda in the EU (particularly its industrial components), and how to balance these with key bilateral relationships like France and Germany. Amid uncertainty about American security guarantees and Russian aggression, the next PM must also consider what Britain’s security role in Europe should be and NATO’s place within that.

Beyond conventional foreign policy issues, Britain is also going to be heavily shaped and influenced by the rule-making power of the EU, and how the world’s largest market regulates itself, from energy to financial services, consumer products and the environment.

The UK will need a strategy to influence the EU from the outside – something Swiss, Norwegians and Americans will acknowledge is no easy feat. This could include significantly increasing its diplomatic footprint across Europe, working closely with the UK’s private and non-profit sectors, utilizing Britain’s technical expertise in areas like sanctions, and creating new ad hoc groupings to share perspectives and ideas, building on examples like the Northern Future Forum

2. Should Britain do business with President Trump?

President Trump represents a fundamental challenge to Britain: an American president whose belligerent unilateralism runs counter to many of Britain’s foreign policy objectives. His frequent and often shameless diplomatic faux pas – from proposing Nigel Farage be the British ambassador to his dog-whistle attacks on the mayor of London – are compounded by real differences of substance on issues like trade, climate change and nuclear non-proliferation.

A new prime minister must decide how to manage relations with the US administration, whether to challenge or condemn a US president when he acts against Britain’s interests, or use flattery or quieter diplomacy to seek to influence him. Theresa May’s strategy of staying politically close to the president and playing to his ego has yielded little in policy terms, though other world leaders have fared little better.

A new PM will face some uncomfortable choices. Will they continue to defend the Iran nuclear deal alongside European allies while the US continues to undermine it? Do they believe a trade deal with America is desirable or achievable with the current administration, and what are they willing to sacrifice to achieve it? Is the American security guarantee for Europe secure with Donald Trump as president? Judgements on these questions should inform Britain's wider strategy, and its objectives for a future relationship with the European Union.

3. Should Britain prioritize economics or security in its relations with China?

Britain faces its own version of the challenge that many countries face – how to balance the economic and investment benefits of a positive relationship with China with concerns about repressive domestic politics and a more assertive Chinese role regionally and globally. This tension has become more acute for two reasons.

First, the economic dislocation of leaving the EU may create a greater reliance on Chinese trade and investment. China is already a major investor in the UK. If Brexit proves to be disorderly, Britain’s need may be all the greater (though China faces economic headwinds as well). Some in Brussels even fear that the economic difficulties of Brexit may make the UK a soft touch for emerging powers from which it seeks inward investment and market access.

Second, the deterioration in US–China relations means the UK may come under increasing pressure from the United States to take a tough line with China. The controversy over Huawei’s role in delivering 5G networks may become a more regular feature of transatlantic debates, with Britain facing Chinese economic pressure on one side and a squeeze from America over security issues on the other, without the weight of the EU behind it.  

A new prime minister should consider whether the UK’s interests are served by a security role in east Asia, and whether it has the capability to play one.

The UK remains a party to the Five Power Defence Arrangements. The Royal Navy has conducted freedom of navigation exercises in the South China Sea, prompting a rebuke from Beijing. It has also taken steps to deepen security ties with Japan.

But the UK government has struggled to present a coherent position. Some cabinet ministers have sought to open doors to the Chinese market at the same time as others announced their intentions to send aircraft carriers to the Pacific. The next PM will need to find a balance between China and the US, or accept the consequences of more directly taking sides on disputes about trade, technology, and security.

4. How can the contradictions between UK foreign and domestic policy be reconciled?

One of the many problems with the vague and unhelpful slogan ‘Global Britain’ is how it jars with many aspects of domestic policy. This incoherence reduces Britain’s foreign policy credibility and effectiveness.

Britain has actively supported the UN-led Yemen peace process while continuing to support Saudi Arabia’s military campaign through arms sales. Britain wants to build a new ambitious independent trade policy while restricting the migration that is crucial for services trade. British foreign secretaries trumpet the UK’s soft power while the Home Office deports members of the Windrush generation, bungles EU citizenship applications and sets unreasonable burdens for many people seeking visas simply to visit the country.

Global universities are celebrated while international students had their post-study visas cut (a policy that sensibly is likely to be reversed). Britain advocates international tax compliance and transparency while not taking robust steps to regulate the tax haven role played by crown dependencies and overseas territories.

A new prime minister has the chance to get to grips with these inconsistencies and develop foreign and domestic policies which are more coherent and self-re-enforcing.

5. At what level should Britain’s international ambitions be funded?

Successive governments have celebrated the fact the UK is the only Western country to spend 2% of GDP on defence and 0.7% on development. However, this masks some real pressures in the system.

There are significant problems in the defence budget and a growing gap between commitments and committed funds. Meanwhile, the funding of Britain’s diplomacy has been cut by successive governments – Labour, Conservative and coalition – for much of the last 20 years. Numerous bodies have highlighted the problems facing the overstretched and underfunded Foreign Office. Where would defence and diplomacy sit in the new prime minister’s hierarchy of priorities?

The problem is not purely one of funding, but the gap between ambitions, rhetoric and resources. It is not sustainable for British ministers to trumpet Britain’s global ambitions while not properly funding the tools of its influence abroad.

It would be reasonable and understandable for a new prime minister to adjust that ambition and tone down the rhetoric, or alternatively to address resource pressures by investing in diplomacy and defence. But that choice should be informed by a sober reflection on Britain’s international position and interests as it leaves the EU. Brexit offers a chance to revisit assumptions that have guided British policy for a generation. A new prime minister should seize this opportunity.

A realistic vision for the future

All these issues will be more pronounced if the UK leaves the EU with no deal at the end of October. ‘No deal’ would be not simply an economic shock but a diplomatic rupture that will colour the UK’s capacity to negotiate a new relationship with the EU, which will be the first order of business after a ‘no deal’ exit. Trust will be in short supply.

Even if they don’t get to vote on the new prime minister, the public deserves serious answers to these and other questions from the men who want to lead the country. Not the platitudes of ‘Global Britain’ or a reflexive and unexamined British exceptionalism, but a serious, realistic assessment of how Britain will cope with the disruptions of leaving the EU and how it might thrive outside the regional bloc it has been a part of for more than 45 years.




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EU Security Ambitions Are Hostage to the Brexit Process

25 June 2019

Professor Richard G Whitman

Associate Fellow, Europe Programme
The EU faces a fundamental contradiction in its goals to become more strategically autonomous in defence matters.

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Soldiers of a Eurocorps detachment raise the EU flag at the European Parliament in Strasbourg. Photo: Getty Images.

Three years ago, as the UK was holding its referendum on Brexit, the EU was rolling out its Global Strategy for a more cohesive and effective security and defence policy. Since then, EU member states have set impressive goals and, as significantly, taken important practical steps to make an EU defence capability a tangible proposition, despite differing collective defence commitments, traditions of neutrality among some member states and very different strategic cultures.

All of these developments have taken place with the UK as reluctant observer. The UK has been traditionally hostile to a deepening of defence collaboration within the EU (and consistent of the view that Europe’s military security was best provided through NATO). But the Brexit referendum vote has placed the UK as a bystander as EU security and defence initiatives have been pursued which have overridden the past red lines of British governments.

There is, however, a Brexit-related paradox in all these developments.

A central goal of the security and defence-related aspects of the EU Global Strategy is for the EU to have the capacity to act independently of the United States and, through indigenous defence industries, the ability to produce the means to make that possible.

With the UK outside the EU, and its opposition absent, it is easier to create a political consensus to push for more defence integration. But without the UK there are diminished collective defence capabilities which would make European strategic autonomy much harder to achieve.  

The May government has been an enthusiast for preserving close security and defence cooperation with the EU. The Withdrawal Agreement and the Political Declaration both seek to provide for a close EU–UK relationship post-Brexit.

However, the Article 50 negotiations have made clear that the EU’s institutions are hostile to special treatment for the UK beyond that normally accorded to a third country. Disagreements over the terms of the UK’s continuing participation in the Gailleo dual-use satellite system, which has a significant security and defence utility, have signalled that there is a strong lobby in Brussels and some national capitals seeking to significantly circumscribe collaboration with Britain.

The scale and capabilities of the UK’s military, its defence expenditure (notably on defence research and development) and its defence industrial base make any British decoupling from the EU’s security and defence a major issue. Disconnecting the UK from EU developments entirely would be a costly political choice for both sides.

And excluding the UK from new initiatives in defence R&D and new defence procurement arrangements would be suboptimal in delivering a stronger European defence, technological and industrial base. Duplicating existing UK capabilities, especially strategic enablers such as strategic airlift, target acquisition and intelligence, surveillance and reconnaissance capabilities, would be an unnecessary squandering of already hard-pressed European defence budgets.

At present the common procurement and defence industry plans driven by the EU Global Strategy are embryonic. And significant defence capability decisions are taking place detached from the EU’s plans, which could reinforce a divide between the UK and other member states.

As illustrative, the formal agreement this week between France, Germany and Spain on the Future Combat Air System (FCAS) to develop a next-generation stealth fighter is competing with the UK-supported Tempest project that shares the same objective. The 20-year timescales for the delivery of the FCAS and Tempest projects are a reminder that defence procurement decisions are of multi-decade significance.

As the EU’s ambitions are nascent, it is too early to fully assess what might be the impact of any decision by the EU and the UK to keep each other at an arms-length in security and defence cooperation. With a more detached relationship, the UK will have significant concerns if it sees the EU’s common procurement arrangements develop in a manner that actively discriminates against the UK defence industry.

Outside of procurement and defence issues there may be other areas of future concern for the UK – for example, the extent to which the EU might deepen and broaden cooperation with NATO in a manner that makes the collective influence of EU member states within NATO more apparent, or to which the footprint of future EU conflict and security activities in third countries starts to overshadow the activities of the UK.

As the UK has been grappling with Brexit domestically, the EU has been evolving its security and defence policy ambitions. These are developments that will impact on the UK and in which, therefore, it has a stake but as a departing member state it has a weakening ability to shape.

Any aspect of future EU–UK cooperation is hostage to the vagaries of how the Brexit endgame concludes.




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Brexit, Party Politics and the Next Prime Minister

Invitation Only Research Event

15 July 2019 - 8:30am to 9:30am

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Daniel Finkelstein OBE, Associate Editor, The Times; Conservative Member of the House of Lords; Chairman, Onward 
Chair: Thomas Raines, Head, Europe Programme, Chatham House

With the new leader of the Conservative party due to be announced on 23 July, what are the prospects for the party and the country?

On Brexit, the new prime minister faces most of the same challenges and constraints as Theresa May. The leadership contenders have outlined their ambitions for a revised deal, but with the EU insisting negotiations are over, their room for manoeuvre appears to be limited. Furthermore, even with a new leader at the helm, important divisions remain among voters about what shape Brexit and the future UK-EU relationship should take. If the EU won’t change the deal, and parliament won’t accept it, how can the deadlock be broken? Is a 'No Deal' Brexit politically deliverable? Or could there be a general election later in 2019? Can the Conservative party survive a pre-Brexit election intact?

Beyond Brexit, what are the other choices, in both domestic and foreign policy, facing the next prime minister? How might the decisions he makes affect the future of the party and British politics more broadly?

In this session, the speaker will share his reflections on the likely result of the leadership election, and what lies beyond it.

Attendance at this event is by invitation only.

Event attributes

Chatham House Rule

Alina Lyadova

Europe Programme Coordinator




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Poland’s Elections: Domestic and Foreign Policy Implications

Research Event

30 September 2019 - 12:30pm to 1:30pm

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Dr Sławomir Dębski, Director, Polish Institute of International Affairs
Dr Stanley Bill, Senior Lecturer in Polish Studies, University of Cambridge

On 13 October 2019, Poland goes to the polls in national elections. On the back of a strong performance in the European elections, the incumbent Law and Justice Party (PiS) is seeking to retain its absolute majority. The election takes place against a background of continued strong economic growth but amid disputes over the direction of social policy and a domestic contest about liberal values. The European Commission and the Polish government have clashed over reforms that the Commission believes could compromise the independence of the judiciary in the Poland. Meanwhile, in foreign policy terms, Poland has sought to develop good working relations with the Trump administration and supported a tough line towards Russia.

The speakers will address the domestic and international significance of the Polish election. Will PiS be able to secure another majority? What would be the implications for the direction of social and political reform in Poland? And how could the elections shift Poland’s approach to politics at the European level and its wider foreign policy?  

Event attributes

Chatham House Rule

Department/project

Alina Lyadova

Europe Programme Coordinator




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What Europe Can Learn From the Law and Justice Party’s Victory in Poland

15 October 2019

Dr Angelos Chryssogelos

Associate Fellow, Europe Programme
The EU must remain vigilant about threats to liberal democracy in Poland, but European leaders must also accept that PiS’s electoral success is reflective of its ability to deliver on things that other political parties in Europe have long neglected.

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The button of a PiS supporter on election day. Photo: Getty Images.

The Polish election on 13 October resulted, as expected, in a victory for of the ruling Law and Justice party (PiS).

But despite again securing a slim majority in parliament, it has not been wholly a triumph for PiS. And though there continue to be concerns about the party’s authoritarian tendencies, the election has illuminated some important nuances to its support and appeal, which hold lessons for politics across Europe.

Even though some opinion polls had suggested PiS were close to winning a supermajority in parliament that would have allowed it to pursue constitutional changes, the party fell short of that target, while it lost its majority in the Senate. Thus, while PiS may well renew its efforts to consolidate its control over the state apparatus and the media or meddle with the justice system, it becomes much more difficult with the opposition controlling the Senate and being able to scrutinize laws or have a say in the appointment of public officials.

Most importantly, the election result has shown that while Polish citizens were willing to reward a party that delivered on promises of economic growth and redistribution, they were not ready to hand a blank cheque for full-blown institutional realignment to PiS. Tellingly, many moderate candidates in PiS lists performed quite well among the party’s voters. 

Even though they rewarded a party that at times employed harsh rhetoric against Brussels, Polish voters have long expressed some of the strongest rates of support for EU membership, according to Eurobarometer surveys. The government has also faced massive protests against its most radical initiatives, such as reform of the judicial system and a law to almost completely ban abortion that was ultimately scrapped. It is therefore more likely that the party’s radicalism kept it from increasing its share, rather than helping it to secure victory.

This is not to say that the threat of illiberalism does not remain alive in Poland. But it shows that the degree of PiS dominance in Poland has never been comparable to that of Fidesz in Hungary, with which it is often compared.

This was reflected in the party’s own rhetoric. In the election campaign the government mostly focused on its economic record, recognizing that much of its support is conditional on conventional measures of political success like voter welfare. PiS may not give up on its ambition to establish a ‘new Polish republic’, but the elections have made it clear that economic stability rather than political radicalism will ensure its longevity in power – with the latter perhaps even being a liability as the party experiences fatigue in office.

Similarly, despite the government’s antagonistic stance towards the EU on various issues, PiS never entertained ideas of withdrawing from the EU, as some of its critics feared earlier in its term. With the Polish economy deeply entwined with the European market and Poland expecting – probably for the last time – to receive substantial subsidies from the next EU budget, EU membership is a necessary precondition for the economic success for which PiS is claiming credit.

With the pro-European left returning to parliament but also an extreme party of the right winning representation, the next government will have a difficult balancing act as it tries to draw on the benefits of EU membership while maintaining its defiant image towards Brussels.

Ultimately, beneath the rhetoric and the posturing, PiS is a party that has shrewdly combined popular policies from the left and right, fulfilling promises of both cultural sovereignty and economic redistribution. Its reelection should not come as a surprise given that it fulfilled its electoral pledges by delivering some of the things that many voters in western Europe also crave but that mainstream parties there have largely failed to provide.




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Britain, the EU and the Power of Myths: What Does Brexit Reveal about Europe?

Invitation Only Research Event

14 November 2019 - 8:30am to 9:30am

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Kalypso Nicolaïdis, Professor of International Relations, Faculty Fellow, St Antony’s College, University of Oxford; Author, Exodus, Reckoning, Sacrifice: Three Meanings of Brexit
Chair: Hans Kundnani, Senior Research Fellow, Europe Programme, Chatham House

When we look back on Brexit, what will it tell us about Europe? Will it simply be that an insular UK was always different and destined to never fit in? Will it be that the UK's decision to leave revealed deeper problems with the EU? Or will it be that the threat created by the UK's withdrawal united the continent and saved the European project?

The speaker will explore Brexit through the prism of biblical and ancient Greek mythology. She will examine the reasons behind Britain’s decision to leave the EU and imagine a ‘better Europe’ that has learnt the lessons of the past and reconciled the divisions exposed by the Brexit vote. How can the EU reinvent itself and re-engage its citizens? And where does a post-Brexit UK fit?

Attendance at this event is by invitation only. 

Event attributes

Chatham House Rule

Alina Lyadova

Europe Programme Coordinator




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Why Britain’s 2019 Election Is Its Most Unpredictable in Recent History

7 November 2019

Professor Matthew Goodwin

Visiting Senior Fellow, Europe Programme
Leadership concerns and a collapse of traditional party loyalties make the December vote uncommonly volatile.

On 12 December, Britain will hold the most consequential election in its postwar history. The outcome of the election will influence not only the fate of Brexit but also the likelihood of a second referendum on EU membership, a second independence referendum in Scotland, the most economically radical Labour Party for a generation, Britain’s foreign and security policy and, ultimately, its position in the wider international order.

If you look only at the latest polls, then the outcome looks fairly certain. Ever since a majority of MPs voted to hold the election, the incumbent Conservative Party has averaged 38%, the opposition Labour Party 27%, the Liberal Democrats 16%, Brexit Party 10%, Greens 4% and Scottish National Party 3%. Prime Minister Boris Johnson and his party continue to average an 11-point lead which, if this holds until the election, would likely deliver a comfortable majority.

Johnson can also point to other favourable metrics. When voters are asked who would make the ‘best prime minister’, a clear plurality (43%) say Johnson while only a small minority (20%) choose the Labour Party leader, Jeremy Corbyn. Polls also suggest that, on the whole, Johnson is more trusted by voters than Corbyn to deal with Brexit, the economy and crime, while Jeremy Corbyn only tends to enjoy leads on health. All of this lends credence to the claim that Britain could be set for a Conservative majority and, in turn, the passing of a withdrawal agreement bill in early 2020.

But these polls also hide a lot of other shifts that are taking place and which, combined, make the 2019 general election unpredictable. One concerns leadership. While Boris Johnson enjoys stronger leadership ratings than Jeremy Corbyn, it should be remembered that what unites Britain’s current generation of party leaders is that they are all unpopular. Data compiled by Ipsos-MORI reveals that while Johnson has the lowest ratings of any new prime minister, Labour’s Jeremy Corbyn has the lowest ratings of any opposition leader since records began.

Another deeper shift is fragmentation. One irony of Britain’s Brexit moment is that ever since the country voted to leave the European Union its politics have looked more ‘European’. Over the past year, one of the world’s most stable two-party systems has imploded into a four-party race, with the anti-Brexit Liberal Democrats and Nigel Farage’s strongly Eurosceptic Brexit Party both presenting a serious challenge to the two mainstream parties.

In the latest polls, for example, Labour and the Conservatives are attracting only 61 per cent of the overall vote, well down on the 80 per cent they polled in 2017. Labour is weakened by the fact that it is only currently attracting 53 per cent of people who voted Labour at the last election, in 2017. A large number of these 2017 Labour voters, nearly one in four, have left for the Liberal Democrats, who are promising to revoke Article 50 and ‘cancel Brexit’. This divide in the Remain vote will produce unpredictable outcomes at the constituency level.

At the other end of the spectrum, the Conservatives are grappling with a similar but less severe threat. Nigel Farage and the Brexit Party are attracting around one in ten people who voted Conservative in 2017, which will make Boris Johnson’s task of capturing the crucial ‘Labour Leave’ seats harder. There is clear evidence that Johnson has been curbing Farage’s appeal, but it remains unclear how this rivalry on the right will play out from one seat to the next.

One clue as to what happens next can be found in those leadership ratings. While 80 per cent of Brexit Party voters back Johnson over Corbyn, only 25 per cent of Liberal Democrat voters back Corbyn over Johnson. Johnson may find it easier to consolidate the Leave vote than Corbyn will find the task of consolidating the Remain vote.

All of this reflects another reason why the election is unpredictable: volatility. This election is already Britain’s fifth nationwide election in only four years. After the 2015 general election, 2016 EU referendum, 2017 general election and 2019 European parliament elections, Britain’s political system and electorate have been in a state of almost continual flux. Along the way, a large number of voters have reassessed their loyalties.

As the British Election Study makes clear, the current rate of ‘vote-switching’ in British politics, where people switch their vote from one election to the next, is largely unprecedented in the post-war era. Across the three elections held in 2010, 2015 and 2017, a striking 49 per cent of people switched their vote.

This is not all about Brexit. Attachment to the main parties has been weakening since the 1960s. But Brexit is now accelerating this process as tribal identities as ‘Remainers’ or ‘Leavers’ cut across traditional party loyalties. All this volatility not only gives good reason to expect further shifts in support during the campaign but to also meet any confident predictions about the election result with a healthy dose of scepticism.




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What Boris Johnson’s Big Win Means for Brexit and Scotland

13 December 2019

Thomas Raines

Director, Europe Programme

Jason Naselli

Senior Digital Editor
Thomas Raines tells Jason Naselli about the impact the large Conservative majority will have on the next phase of Brexit negotiations and Scotland’s place in the United Kingdom.

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Boris Johnson speaks after the Conservatives secured a majority in the UK general election. Photo: Getty Images.

What does the UK election result mean for Brexit and forthcoming trade negotiations with the EU?

The most important thing is that it means Brexit will definitely happen. Since the referendum, we’ve had three-and-a-half years of continued uncertainty where all outcomes were still possible. We now know that Brexit will become irreversible from 31 January.

That’s the biggest thing, because I think that will have a big psychological impact on politics, both in the UK and also on the EU side. The EU has been working with a partner that has been unsure about its direction, and perhaps some had still hoped that the process might still be reversed, but that direction is now completely clear.

Obviously the first order of business is to pass the withdrawal agreement, which should be pretty straightforward given the majority that the Conservatives have. That’s a formality now.

Then, the question becomes about the level of ambition for the next year. It is an exceptionally ambitious timetable to negotiate, ratify and implement a new relationship before the end of the transition period in December 2020.

What is achievable by the end of next year?

I think there are three possible outcomes here. One: that timetable doesn’t work and Boris Johnson follows through on his pledge to leave the transition period anyway, leading to a ‘no trade deal’ outcome.

Two: the negotiations are able to deliver something by the end of 2020, either because the depth and ambition of any agreement is relatively low level (what Michel Barnier has called a ‘vital minimum’)  and/or because they come up with some type of compromise on the process which is not called an extension, but something else: a type of temporary agreement or a new implementation period.

This is a situation where you might have a bare-bones agreement for the end of the transition period, but with an extended period of negotiation for different unresolved issues. The EU will probably insist upon level playing field guarantees and fishing access rights as a component of any such agreement.

Three: Boris Johnson breaks his manifesto pledge not to extend the transition. Now, he has stared down the barrel of leaving with no deal before and he made a political judgment that it was better to make significant compromises on his negotiating position than to follow through with ‘no deal’. I suspect he might make that same judgment again.

No option is ideal. The first is the most economically disruptive, the second means the EU will be in an even stronger position to dictate terms and the third means breaking a manifesto pledge.

How important is that end of transition deadline now? It was an important issue for the Brexit Party and hardliners in the European Research Group of Conservative MPs. But given the size of a majority, he may need to worry less about them. Is the transition deadline that important to people who voted Conservative, especially if he can show that he has taken the UK out of the EU by the end of January?

I think there may indeed be some political space for Johnson here, given the size of his majority and given that the first phase of Brexit will have been done, along with the debate about withdrawal.

There will be a lot of difficult, technical negotiations in all sorts of areas, some of which I think will become quite rancorous, but won’t necessarily become front page news in the way some of the first phase of negotiations has, not least because you won’t have the theatre of a hung parliament.

Hopefully, there will be more focus on the substance of the agreement, and the debate will be about the consequences of divergence versus staying more aligned with the EU, which is basically the central question now about the future relationship.

I still think for UK prime ministers to pick arbitrary dates, and then to make domestic political promises based around them, actually undermines the UK’s negotiating position. It would be in Britain’s interest to have more flexibility rather than a ticking clock.

Moving to the other big story from the night, the SNP won 48 of 59 seats in Scotland. How does the debate over Scotland’s future in the United Kingdom play out from here?

The SNP has really strengthened its position, more than many expected. This is now set up for a huge constitutional struggle over the future of the United Kingdom.

I think there is a key dilemma for Scottish independence supporters, which is that on the one hand Brexit greatly strengthens the political case for independence. The difference between the political preferences in Scotland and the rest of the UK, particularly in England, is a perfect demonstration of that.

At the same time, once the UK has left the EU, independence becomes much more difficult technically and economically. There will be many of the same difficulties that there have been in discussing Northern Ireland’s relationship with the Republic of Ireland. There will be a difficult debate over the currency. There are all sorts of challenges to creating a trade or regulatory border between England and Scotland. This is particularly true if there is a harder Brexit outcome, where Britain leaves the EU without a large amount of regulatory alignment.

On demands for a second independence referendum, I think in the first instance Boris Johnson will simply refuse to hold one. It’s probably not in his short-term interest to do anything else. Theresa May played it this way in 2017, repeatedly saying ‘now is not the time’.

In a similar way I think Johnson will just try to ride the pressure out, to the point where the SNP will need to face the challenges of advocating independence with the UK outside the EU. The next flashpoint will be the elections to the Scottish Parliament in 2021.

Ultimately, though, it will become a democratically unsustainable position if Scotland continues to vote for the SNP, and refusing to sanction a second independence referendum might only reinforce that sentiment.

Follow Chatham House Twitter for more election coverage




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Don’t Be Afraid of Political Fragmentation

16 December 2019

Pepijn Bergsen

Research Fellow, Europe Programme
If managed correctly, splintering and more volatile political systems – so-called ‘Dutchification’ – need not be a ticket to political and policy paralysis.

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Voters cast their vote as part of the Dutch general elections on March 15, 2017 at a polling station in a mill in Oisterwijk. Photo by ROB ENGELAAR/AFP via Getty Images.

In recent decades, political party systems across Europe have fragmented and electoral volatility has increased. The number of parties represented in parliaments across the continent has grown and the formerly dominant mainstream parties have seen their support base collapse, forcing parties into often uncomfortable and unstable coalitions.

From the United Kingdom to Germany, politicians and commentators talk of such scenarios in often apocalyptic terms and associate it with political instability and policy paralysis.

They shouldn’t. Instead they should focus their energy on making these increasingly competitive political markets work.

The Netherlands is frequently held up as a prime example of this process, which is therefore sometimes referred to as ‘Dutchification’. Its highly proportional political system has created the opportunity for new parties and specific interest groups to win parliamentary representation, ranging from an animal rights party and a party catering specifically to the interests of the elderly.

This has been accompanied by increased electoral volatility. In the 1970s, less than 15% of seats in the Dutch parliament would change party at any election, but in the last election in 2017, this was just over a quarter. The system also created space for the relatively early rise of populist far-right parties, though it was not the cause of their rise.

Nevertheless, despite the regularly difficult coalition politics, it remains one of the most well-governed countries in the world.

A short history of fragmentation

Looking at the effective number of parties represented in parliaments, the number of parties, corrected for their size, provides a good measure of the extent of fragmentation. In the Netherlands this steadily increased from around four in the 1980s to over eight following the election in 2017. Even the populist far-right vote has fragmented, with two parties partly competing for the same electorate. In other countries it has been a more recent phenomenon. Spain remained a de facto two-party system until the financial crisis. Dissatisfaction with both mainstream parties has seen challenger parties on both the left and the right attract significant support, making it harder to form stable coalitions. Political fragmentation decreased slightly in Italy in recent years, but that was from a high base as it shot up in the early 1990s when the post-war political settlement crumbled.

German politics, long a hallmark of stability, is struggling with the decrease in support for the parties that dominated its political scene in the post-war period. The Christian Democrats and Social Democrats only barely managed to win a majority together in the election in 2017, at 53.4% of the vote compared with the 81.3% achieved 30 years earlier. The latest polls suggest they would only get to 40% together if an election were held today.

A similar trend is visible within the European Parliament. Whereas the two largest groups in the European Parliament, the Christian Democrats and the Social Democrats, together won 66% of the vote in the election in 1999, they did not even manage to win a majority together in 2019, taking just 39.5% of the vote.

No crisis of democracy

If electoral volatility and political fragmentation does indeed constitute some sort of crisis of democracy, we should expect to see voters become unhappy about how their national democracy functions. Largely, the opposite seems to be the case.

In the Netherlands, satisfaction with its democracy went up at the same time as Dutchification did its work. Similar trends are visible in other highly fragmented European political systems, often those with very proportional systems. Despite regular minority governments, satisfaction with democracy is above 90% in Denmark and at 80% in Sweden, according to the latest Eurobarometer data.

In comparison, it stood at 52% in the United Kingdom and 53% in France, where the electoral system has, at least on the surface, prevented the kind of fragmentation supposedly plaguing proportional systems.

Satisfaction with democracy seems to be affected by a number of factors. This includes the state of the economy, particularly in countries that were hit the hardest by the global financial and euro zone crises. Nevertheless, the data suggests that, even if we can’t say that Dutchification by definition leads to more satisfaction with democracy, it is clearly not associated with falling faith in the system.

A competitive political market

Dutchification should be seen as accompanying a more competitive political marketplace. A more emancipated, demanding and politically engaged electorate than in the post-war decades is willing to shop around instead of merely vote according to socioeconomic class or other dividing lines, such as religious ones. The fragmented parliaments that emerge as a result provide better representation of different groups within European societies.

This makes life harder for Europe’s political parties and politicians, as they juggle large coalitions, or changing coalitions under minority governments, but provides voters with more choice and democratic renewal. If handled correctly this would also allow more responsiveness to shifts in public opinion.

Such democratic creative destruction in competitive political markets is to be celebrated in a well-functioning democracy. Just as companies prefer to operate in an oligopoly, political parties prefer the stability of limited political competition. But wishing for this kind of stability comes perilously close to preferring stability over proper representation.

Worrying about Dutchification risks confusing a crisis of the traditional mainstream parties with a crisis of democracy. For some countries, particularly those like the Netherlands and Denmark which have longer histories of consensus-based politics and coalition building, this is an easier adjustment. But this should not be an excuse to not attempt to make politics work better as they were forced to go through, arguably still ongoing, adjustment processes too.

Instead of investing in futile attempts to get back to how things were in the old days, or hoping this will somehow magically happen, political leaders and parties across Europe need to reassess how they deal with the new reality of Dutchification.




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In Next Round of EU Negotiations, Britain Faces Familiar Pitfalls

31 January 2020

Thomas Raines

Director, Europe Programme

Professor Richard G Whitman

Associate Fellow, Europe Programme
Despite being free of the constraints and the theatre of a hung parliament, there is a risk that over the coming year the British government repeats too many of the mistakes of the withdrawal negotiations.

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The Elizabeth Tower remains under renovation on 31 January 2020. Photo: Getty Images.

Whether feared or longed for, Brexit day has arrived. It is positive for all sides that the process is thus far managed and ordered, with debts paid, rights guaranteed and borders still invisible on the island of Ireland. But in a difficult new phase of negotiations, as the UK and EU try to hammer out the terms of their relationship after 2020, Britain is at risk of repeating many of its mistakes from the withdrawal talks.

First, the government, through the negotiation timeline, has reduced its own room for manoeuvre. The failure of the initial withdrawal agreement and subsequent turbulent politics have reduced a planned 21-month transition to an 11-month one. Even though half the original negotiation time has been lost, 31 December 2020 remains in place and indeed has been written into UK law as the date the transition arrangement ends. Boris Johnson has followed Theresa May in investing symbolism and significance in an arbitrary date.

By promising not to extend negotiations, the UK is boxing itself in, creating domestic political barriers where it may well need flexibility. The familiar face of Michel Barnier, who proved adept in leading the withdrawal negotiations for the EU side, will be back in phase two to tell Britain the clock is ticking. This new timeline is intended to focus minds but more likely it will limit ambitions. 

Second, this government has continued the pattern of its predecessor in making no effort to manage public expectations about the consequences of Brexit. It is naïve to have followed the last years of British politics and expect an outbreak of sobriety and levelheadedness. The entrenched positions of each side have offered little political space or electoral incentive for realism.

During the 2020 transition period, the UK will lose the political rights of EU membership but it will retain the benefits and obligations. Most citizens and business will not be able to tell the difference. But a reckoning is inevitable. There will come a moment when the effects of this slow-motion political revolution – particularly in the hard form envisioned by Boris Johnson – become real, when the trade-offs and compromises, especially for business and the economy, will bite. The public deserve some realism about the price of sovereignty.

Third, there is a risk that government remains underprepared. While its headline goals are clear – at least in terms of what it does not want – the UK government will need thorough, realistic and coherent proposals on what it wants in every area of negotiations, and crucially develop a process by which to make political trade-offs between the demands of different sectors and issues. The government must also then prepare for their implementation in every area. This would be a huge challenge even if the final destination was already known, which it is not. 

Fourth, the continued uncertainty in the process means businesses and civil servants will again be left with little time to adapt to what will face them in January 2021 and must prepare for multiple outcomes.

‘Transition’ has always been a misleading term, since it implies clarity about the destination to which the UK–EU relationship will be transitioning. The government’s red lines for that future relationship provide a sketch: outside of the single market and the jurisdiction of the European Court of Justice, with an independent trade policy and free movement ended.

But businesses and civil servants are not likely to know until very late in the process if the basis for future trade with the EU will be in the form of a free trade agreement, to be negotiated and implemented by the end of the year, or no trade deal at all. This last outcome is a realistic prospect.

Michel Barnier speaks in the European Parliament on 29 January. Photo: Getty Images.

During withdrawal negotiations, the extensions were both unlimited in number and required decisions only at the last moment. In this phase, the talks may only be extended once, and that decision must be taken six months from the final deadline. It is difficult to see circumstances in which Boris Johnson agrees to break a political promise and manifesto pledge when he still has six more months to achieve his desired outcome.

The UK, it is often noted, is already fully compliant with EU law and this shared starting point is often cited as a reason this negotiation will be simple, since the parties begin in alignment. But this novel negotiation will create new trade barriers in goods and services rather than remove them. Trade deals are often politically difficult since they create winners and losers. The Brexit negotiations, in terms of UK–EU trade at least, will generally create only different levels of losers, on both sides of the Channel.

That means difficult politics, challenging negotiations and hard compromises, another reason to expect some ugly politics along the way and accept that failure is a plausible outcome.

We do not yet know how Brexit will change Britain in the long term, whether a settled majority will ever come to view it as political folly or liberation, choice or inevitability. If its politically fragile union can withstand the pressures of the next few years, the UK may yet find a new stable position on the EU’s periphery and, after a period of economic adjustment, begin to address the many pressing domestic challenges which have suffered from neglect amid the all-consuming Brexit saga.

But whatever happens in this next chapter, the EU can no longer be an excuse for national problems. As the UK takes back control it also returns accountability. In the future, there will be no one else to credit or to blame.




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Germany in 2020: European and Global Priorities

Invitation Only Research Event

28 February 2020 - 8:30am to 11:00am

Chatham House | 10 St James's Square | London | SW1Y 4LE

This roundtable brings together German experts to discuss the country’s role in Europe and the world. Over the course of two sessions, Germany’s EU and wider foreign policy will be examined, with speakers sharing their views on where the country finds itself at the beginning of 2020 and what drives its current priorities across a number of areas. Participants will also compare perspectives on what a post-Merkel Germany might look like, now that the future leadership of CDU, Germany’s largest political party, is under question.

The event will comprise two separate sessions. Participants are welcome to attend either one or both.

08.30 – 09.30
Germany in the EU and the Eurozone

Speaker: Mark Schieritz, Economics Correspondent, Die Zeit
Chair: Quentin Peel, Associate Fellow, Europe Programme, Chatham House

Germany’s voice remains possibly the most important in any debate within the EU, including in those around the future of the Eurozone. The country has long been seen as the stalwart of the European economy and its government has always played a key role in driving Eurozone policy. However, most recent EU-wide attempts at reform have fallen short of what many claim needs to be done to complete the monetary union. The recently announced Eurozone budgetary instrument, for instance, remains very small and only focused on investment instead of stabilisation. The German government has been reluctant to go along with French President Emmanuel Macron and his structural reform proposals, though some other member states remain sceptical of his ideas for further integration too.

How can German attitudes towards the future of the Eurozone be explained? Is the government’s resistance to ambitious EU-wide economic reforms shared across the political spectrum in Germany? What stands in the way of further Eurozone reform when it comes to other EU member states? And will Germany’s reluctance to engage with reforms in this area, make it more difficult for the country to build coalitions when it comes to other EU policy areas?

09.45 – 11.00
German Foreign Policy in Perspective

Speakers: Joshua Webb, Programme Manager, Berlin Foreign Policy Forum and the Berlin Pulse, Koerber Stiftung
Dr Nicolai von Ondarza, Deputy Head, EU/Europe Research Division, German Institute for International and Security Affairs (SWP)
Chair: Dr Uta Staiger, Executive Director, UCL European Institute

Historically, Germany has been reluctant to play too active a role on the global stage, relying on its place at the heart of Europe and the transatlantic alliance. However, the current uncertain global context appears to have led to some rethinking on how the country can ensure its voice is being heard internationally, especially where its values are being challenged and its interests are at stake.

What drives German foreign policy in 2020? What are domestic priorities when it comes to trade, security and Germany’s place in the world? What shifts in public opinion may have been engendered by Brexit and Donald Trump’s presidency? What does the rise of China – and China’s growing interest in Europe – mean for Germany’s wider Asia policy?  Finally, what role will Germany play in a post-Brexit Europe? And what are the country’s priorities in its future relationship with the UK?

The speakers will discuss these and other questions, sharing the findings of a recent German public opinion survey and compare these with international expert perspectives. 

Event attributes

Chatham House Rule

Alina Lyadova

Europe Programme Coordinator




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A Credit-fuelled Economic Recovery Stores Up Trouble for Turkey

17 February 2020

Fadi Hakura

Consulting Fellow, Europe Programme
Turkey is repeating the mistakes that led to the 2018 lira crisis and another freefall for the currency may not be far off.

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Headquarters of the Central Bank of the Republic of Turkey. Photo: Getty Images.

Since the 2018 economic crisis, when the value of the lira plummeted and borrowing costs soared, Turkey’s economy has achieved a miraculous ‘V-shaped’ economic recovery from a recession lasting three quarters to a return back to quarterly growth above 1 per cent in the first three months of 2019.

But this quick turnaround has been built on vast amounts of cheap credit used to re-stimulate a consumption and construction boom. This so-called ‘triple C’ economy generated a rapid growth spurt akin to a modestly able professional sprinter injected with steroids.

This has made the currency vulnerable. The lira has steadily depreciated by 11 per cent against the US dollar since the beginning of 2019 and crossed the rate of 6 lira versus the US dollar on 7 February. And there are further warning signs on the horizon.

Credit bonanza

Statistics reveal that Turkish domestic credit grew by around 13 per cent on average throughout 2019.  The credit bonanza is still ongoing. Mortgage-backed home sales jumped by a record high of 600 per cent last December alone and the 2019 budget deficit catapulted by 70 per cent due to higher government spending.

Turkey’s central bank fuelled this credit expansion by cutting interest rates aggressively to below inflation and, since the start of this year, purchasing lira-denominated bonds equivalent to around one-third of total acquisitions last year to push yields lower.

Equally, it has linked bank lending to reserve requirements – the money that banks have to keep at the central bank – to boost borrowings via state and private banks. Banks with a ‘real’ loan growth (including inflation) of between 5 and 15 per cent enjoy a 2 per cent reserve ratio on most lira deposits, which authorities adjusted from an earlier band of 10-20 per cent that did not consider double-digit inflation.

Cumulatively, bond purchases (effectively quantitative easing) and reserve management policies have also contributed to eased credit conditions.

Commercial banks have also reduced deposit rates on lira accounts to less than inflation to encourage consumption over saving. Together with low lending rates, the boost to the economy has flowed via mortgages, credit card loans, vehicle leasing transactions and general business borrowings.

Accordingly, stimulus is at the forefront of the government’s economic approach, as it was in 2017 and 2018. It does not seem to be implementing structural change to re-orient growth away from consumption towards productivity. 

In addition, governance is, again, a central issue. President Recep Tayyip Erdogan’s near total monopolization of policymaking means he guides all domestic and external policies. He forced out the previous central bank governor, Murat Cetinkaya, in July 2019 because he did not share the president’s desire for an accelerated pace of interest rate reductions.

New challenges

Despite the similarities, the expected future financial turbulence will be materially different from its 2018 predecessor in four crucial respects. 

Firstly, foreign investors will only be marginally involved. Turkey has shut out foreign investors since 2018 from lira-denominated assets by restricting lira swap arrangements. Unsurprisingly, the non-resident holdings of lira bonds has plummeted from 20 per cent in 2018 to less than 10 per cent today.

Secondly, the Turkish government has recently introduced indirect domestic capital controls by constraining most commercial transactions to the lira rather than to the US dollar or euro to reduce foreign currency demand in light of short-term external debt obligations of $191 billion.

Thirdly, the Turkish state banks are intervening quite regularly to soften Lira volatility, thereby transitioning from a ‘free float’ to a ‘managed float’. So far, they have spent over $37 billion over the last two years in a futile effort to buttress the lira. This level of involvement in currency markets cannot be maintained.

Fourthly, the Turkish state is being far more interventionist in the Turkish stock exchange and bond markets to keep asset prices elevated. Government-controlled local funds have participated in the Borsa Istanbul and state banks in sovereign debt to sustain rallies or reverse a bear market.  

All these measures have one running idea: exclude foreign investors and no crisis will recur. Yet, when the credit boom heads to a downturn sooner or later, Turks will probably escalate lira conversions to US dollars; 51 per cent of all Turkish bank deposits are already dollar-denominated and the figure is still rising.

If Turkey’s limited foreign reserves cannot satisfy the domestic dollar demand, the government may have to impose comprehensive capital controls and allow for a double digit depreciation in the value of the lira to from its current level, with significant repercussions on Turkey’s political stability and economic climate.

To avoid this scenario, it needs to restore fiscal and monetary prudence, deal the with the foreign debt overhang in the private sector and focus on productivity-improving economic and institutional reforms to gain the confidence of global financial markets and Turks alike.




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The Future of Democracy in Europe: Technology and the Evolution of Representation

3 March 2020

To the extent that perceptions of a crisis in liberal democracy in Europe can be confirmed, this paper investigates the nature of the problem and its causes, and asks what part, if any, digital technology plays in it.

Hans Kundnani

Senior Research Fellow, Europe Programme

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A woman writes a note on the Savita Halappanavar mural in Dublin on 26 May 2018, following a referendum on the 36th amendment to Ireland’s constitution. The referendum result was overwhelmingly in favour of removing the country’s previous near-universal ban on abortion. Photo: Getty Images.

Summary

  • There is a widespread sense that liberal democracy is in crisis, but little consensus exists on the specific nature and causes of the crisis. In particular, there are three prisms through which the crisis is usually seen: the rise of ‘populism’, ‘democratic deconsolidation’, and a ‘hollowing out’ of democracy. Each reflects normative assumptions about democracy.
  • The exact role of digital technology in the crisis is disputed. Despite the widely held perception that social media is undermining democracy, the evidence for this is limited. Over the longer term, the further development of digital technology could undermine the fundamental preconditions for democracy – though the pace and breadth of technological change make predictions about its future impact difficult.
  • Democracy functions in different ways in different European countries, with political systems on the continent ranging from ‘majoritarian democracies’ such as the UK to ‘consensual democracies’ such as Belgium and Switzerland. However, no type seems to be immune from the crisis. The political systems of EU member states also interact in diverse ways with the EU’s own structure, which is problematic for representative democracy as conventionally understood, but difficult to reform.
  • Political parties, central to the model of representative democracy that emerged in the late 18th century, have long seemed to be in decline. Recently there have been some signs of a reversal of this trend, with the emergence of parties that have used digital technology in innovative ways to reconnect with citizens. Traditional parties can learn from these new ‘digital parties’.
  • Recent years have also seen a proliferation of experiments in direct and deliberative democracy. There is a need for more experimentation in these alternative forms of democracy, and for further evaluation of how they can be integrated into the existing institutions and processes of representative democracy at the local, regional, national and EU levels.
  • We should not think of democracy in a static way – that is, as a system that can be perfected once and for all and then simply maintained and defended against threats. Democracy has continually evolved and now needs to evolve further. The solution to the crisis will not be to attempt to limit democracy in response to pressure from ‘populism’ but to deepen it further as part of a ‘democratization of democracy’.




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Another CDU Leadership Race Begins in Merkel’s Shadow

28 February 2020

Quentin Peel

Associate Fellow, Europe Programme
The election of a new leader of the chancellor’s party will be another contest over her legacy.

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German Chancellor Angela Merkel is depicted on a float in the Rosenmontag parade in Mainz on 24 February. Photo: Getty Images.

Perhaps it will be second time lucky. At the end of April, Germany’s Christian Democratic Union (CDU) will elect a new party leader to follow in the footsteps of Angela Merkel. An emergency party congress has been summoned to do that after the surprise resignation of Annegret Kramp-Karrenbauer, Merkel’s chosen successor.

The plan is to leave the decision on who will be the CDU candidate for chancellor at the next election until after Germany’s EU presidency concludes in December. So Merkel will keep her job until 2021, and the new leader will have to learn to live with her.

The three leading candidates are Armin Laschet, Friedrich Merz and Norbert Röttgen, all from the state of North Rhine-Westphalia. Two of the three – Merz and Röttgen – were sacked by Merkel from their former jobs. They have not forgotten. Only Armin Laschet, currently CDU leader in North Rhine-Westphalia and state premier, can be described as a Merkel loyalist, true to her centrist mantra.

He is the man to beat, having teamed up with Jens Spahn, the 39-year-old health minister, who is popular with party conservatives. Spahn will run as his deputy, so the team straddles the left-right divide in the party. But the contest still seems set to be a bitter battle between pro- and anti-Merkel factions that could leave the party badly split.

After nearly 15 years as chancellor, and 18 years as CDU leader, Merkel remains the most popular politician in Germany. In spite of criticism that she lacks vision, her caution and predictability appear to be just what most German voters like.

But her term in office has also seen the steady shrinking of the centre ground in German politics, with the rise of the environmentalist Green party and the far-right Alternative for Germany (AfD) at the expense of the centre-right CDU and the centre-left Social Democratic Party (SPD).

The battle for the soul of the CDU is between those who think Merkel has been too left-wing, and want a more conservative leader to win back AfD voters, and those who believe that the CDU must stay in the centre, and prepare for a future coalition with the Greens. Merz is seen as the former, Laschet and Röttgen the latter.

Unless Laschet emerges as the clear winner in April, the leadership contest is likely to leave Germany sorely distracted by domestic politics just as it takes over the EU presidency in the second half of the year. Instead of Merkel having a triumphant international swansong on the EU stage, she could be battling to protect her inheritance at home.

The one area on which all three leadership candidates seem to agree is foreign policy: they all want Germany to take more leadership and responsibility, and for the European Union to play a bigger role in security, defence and international affairs. They are all Atlanticists, but critical of Donald Trump’s ‘America First’ stance. All are on the record criticizing the chancellor – at least tacitly – for not having a more vigorous foreign policy.

There the similarity ends.

On the right, the 64-year-old Merz is both the most conservative and the most popular with the party grassroots. He fell out with the chancellor when she took over his job as CDU leader in parliament in 2002. He quit politics to become a corporate lawyer (and a millionaire), but never lost his political ambition. He is an economic liberal but socially conservative, a strong critic of Merkel’s migration policy and her lack of clear leadership. Critics say he is a man of the past, and not a team player.

On the EU, he believes Germany is ‘leaving too much to the French’. If France and Germany cannot agree on financial matters, he said at the London School of Economics in February, they should instead forge a stronger EU industrial policy focused on creating more ‘European champions’.

Laschet, the Merkel loyalist, is four years younger, and from the left of the party. Like Merz, he is a former member of the European parliament. In 2015, he defended Merkel’s open border policy to accept refugees stranded in the Balkans. On Russia, however, he is more critical, calling for a new effort to re-engage with Vladimir Putin. Most recently, at the Munich Security Conference, he called for stronger Franco-German relations, and more support for the eurozone reforms proposed by Emmanuel Macron.

As CDU leader in North Rhine-Westphalia, Laschet has the strongest power base. He earned his political spurs there by winning the last state election in 2017, in contrast to Röttgen, who lost to the SPD and Greens five years earlier.

Röttgen, chairman of the Bundestag foreign affairs committee, is the surprise candidate. Once a Merkel favourite, they fell out when she sacked him as environment minister after he lost the North Rhine-Westphalia election. By throwing his hat in the ring, he has forced it to become an open contest. He is independent-minded and outspoken, but not as bitterly hostile to the chancellor as Merz, so he could be a compromise candidate.

Laschet is clearly the man Merkel would find it easiest to live with. The decision will be taken by a party congress, not a grassroots ballot, which gives him a better chance. But Merz is the most eloquent orator and seen as the best campaigner. The challenge for party members is whether they believe it is better to swing right and squeeze the AfD, or stick to the centre to hold onto voters tempted by the Greens, who have replaced the SPD as the second-most popular party in Germany.

The race is wide open. So is the future of the CDU. The only prediction one can make with much certainty is that as long as Merkel remains chancellor, any successor will struggle to get out of her shadow.




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Coronavirus and the Future of Democracy in Europe

31 March 2020

Hans Kundnani

Senior Research Fellow, Europe Programme
The pandemic raises difficult questions about whether liberal democracies can adequately protect their citizens.

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Police officers wearing protective face masks patrol during coronavirus lockdown enforcement in Wroclaw, Poland. Photo by Bartek Sadowski/Bloomberg via Getty Images.

It is less than a month since we published our research paper on the future of democracy in Europe. But it feels like we now live in a different world. The coronavirus has already killed thousands of people in Europe, led to an unprecedented economic crisis and transformed daily life – and in the process raised difficult new questions about democracy.

The essence of our argument in the paper was that democracy in Europe should be deepened. But now there is a much more basic question about whether democracies can protect their citizens from the pandemic.

There has already been much discussion about whether authoritarian states will emerge stronger from this crisis than democracies. In particular, although the virus originated in China and the government initially seemed to struggle to deal with it, it was able to largely contain the outbreak in Hubei and deploy vast resources from the rest of the country to deal with it.

Come through the worst

China may have come through the worst of the health crisis – though a second wave of infections as restrictions are lifted is possible – and there have already been three times as many deaths in Italy, and twice as many in Spain, as in China (although there is increasing doubt about the accuracy of China’s figures).

However, it is not only authoritarian states that seem so far to have coped relatively well with the virus. In fact, some East Asian democracies appear to have done even better than China. At the time of writing South Korea, with a population of 51.5 million, has had only 144 death rates so far. Taiwan, with a population of nearly 24 million, has had only two deaths.

So rather than thinking in terms of the relative performance of authoritarian states and democracies, perhaps instead we should be asking what we in Europe can learn from East Asian democracies.

It is not yet clear why East Asian democracies were able to respond so effectively, especially as they did not all follow exactly the same approach. Whereas some quickly imposed restrictions on travel (for example, Taiwan suspended flights from China and then prohibited the entry of people from China and other affected countries) and quarantines, others used extensive testing and contact tracing, often making use of personal data collected from citizens.

Whatever the exact strategy they used, though, they did all act quickly and decisively – and the collective memory of the SARS outbreak in 2003 and other recent epidemics seems to have played a role in this. For example, following the SARS outbreak, Taiwan created a central epidemic command center. Europe, meanwhile, was hardly affected by SARS – and we seem to have assumed the coronavirus would be the same (although that does not quite explain why we were still so slow to react in February even after it was clear that the virus had spread to Italy).

However, while the relative success of East Asian democracies may have something to do with this recent experience of epidemics, it may also have something to do with the kind of democracies they are. It may be a simple matter of competence – the bureaucracy in Taiwan and South Korea may function better, and in particular in a more coordinated way, than in many European countries.

But it may also be more than that. In particular, it could be that East Asian democracies have a kind of 'authoritarian residue' that has helped in the initial response to this crisis. South Korea and Taiwan are certainly vibrant democracies – but they are also relatively new democracies compared to many in Europe. As a result, citizens may have a different relationship with the state and be more willing to accept sudden restrictions of freedoms, in particular on movement, and the use of personal data – at least in a crisis.

In that sense, the pandemic may be a challenge not to democracy as such but to liberal democracy in particular – in other words, a system of popular sovereignty together with guaranteed basic rights, such as including freedom of association and expression and checks and balances on executive power. There may now be difficult trade-offs to be made between those basic rights and security – and, after the experience of coronavirus, many citizens may choose security.

This brings us back to the issues we discussed in our research paper. Even before the coronavirus hit, there was already much discussion of a crisis of liberal democracy. In particular, there has been a debate about whether liberalism and democracy, which had long been assumed to go together, were becoming decoupled.

In particular, ‘illiberal democracies’ seemed to be emerging in many places including Europe (although, as we discuss in the paper, some analysts argue that the term is incoherent). This model of ‘illiberal democracy’ – in other words, one in which elections continue to be held but some individual rights are curtailed – may emerge stronger from this new crisis.

It is striking that Singapore – also seen as responding successfully to coronavirus – was seen as a paradigmatic ‘illiberal democracy’ long before Hungarian Prime Minister Viktor Orbán embraced the idea. In particular, there is little real opposition to the People’s Action Party, which has been in power since 1959.

Since this new crisis began, Orbán has gone further in suspending rights in Hungary. On March 11, he declared a state of emergency – as many other European countries have also done. But he has now gone further by passing legislation that allows him to govern by decree indefinitely and make it illegal to spread misinformation that undermines the government’s response to the pandemic. Clearly, this is a further decisive step in the deconsolidation of liberal democracy in Hungary.

So far, though, much of the discussion, particularly in the foreign policy world, has focused mainly on how to change popular perceptions that liberal democracies are failing in this crisis. For example, High Representative Josep Borrell, the European Union’s foreign minister, wrote last week of a 'battle of narratives'.

But this misses the point. It is not a matter of spinning the European model, but of taking seriously the substantial questions raised by the coronavirus about the ability of liberal democracies to adequately protect their citizens.




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Virtual Breakfast: Engaging with the EU From the Outside: A Perspective From Norway

Invitation Only Research Event

24 April 2020 - 8:30am to 9:30am

Event participants

Niels Engelschiøn, Director-General, Department for European Affairs, Norwegian Ministry of Foreign Affairs
Chair: Dr Robin Niblett, Director; Chief Executive, Chatham House

Please note this an online-only event.

Norway is one of the few European countries that remains outside of the European Union. After the country’s population rejected the prospect of joining the EU twice, Norway’s relationship with the Union has been based on its membership of the European Economic Area (EEA), alongside Iceland and Liechtenstein.

The ‘Norway Model’ was often mentioned in the run up to the Brexit vote as a possible basis for Britain’s future relationship with the bloc, not least because it offers the least disruption to the current arrangement. Equally, Norway is not subject to the EU fisheries policy - an anticipated major issue in the next phase of Brexit talks. Nor is it part of the EU Customs Union.

Even though Prime Minister Johnson has now ruled out the type of deep economic and regulatory integration with the EU that Norway enjoys through its EEA membership, the country’s experience can still offer valuable lessons for the UK as it prepares to exit the transition period at the end of 2020.

In this session, the speaker will share Norway’s experience as a long-standing EEA member and discuss the challenges of engaging with the EU from the outside. What lessons can Norway offer the UK ahead of the negotiations on the future of UK-EU relations? What are the limits of its current arrangement with the EU? And is there any appetite among the Norwegian population to revisit it?

Alina Lyadova

Europe Programme Coordinator




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Biochemical and structural insights into how amino acids regulate pyruvate kinase muscle isoform 2 [Enzymology]

Pyruvate kinase muscle isoform 2 (PKM2) is a key glycolytic enzyme involved in ATP generation and critical for cancer metabolism. PKM2 is expressed in many human cancers and is regulated by complex mechanisms that promote tumor growth and proliferation. Therefore, it is considered an attractive therapeutic target for modulating tumor metabolism. Various stimuli allosterically regulate PKM2 by cycling it between highly active and less active states. Several small molecules activate PKM2 by binding to its intersubunit interface. Serine and cysteine serve as an activator and inhibitor of PKM2, respectively, by binding to its amino acid (AA)-binding pocket, which therefore represents a potential druggable site. Despite binding similarly to PKM2, how cysteine and serine differentially regulate this enzyme remains elusive. Using kinetic analyses, fluorescence binding, X-ray crystallography, and gel filtration experiments with asparagine, aspartate, and valine as PKM2 ligands, we examined whether the differences in the side-chain polarity of these AAs trigger distinct allosteric responses in PKM2. We found that Asn (polar) and Asp (charged) activate PKM2 and that Val (hydrophobic) inhibits it. The results also indicate that both Asn and Asp can restore the activity of Val-inhibited PKM2. AA-bound crystal structures of PKM2 displayed distinctive interactions within the binding pocket, causing unique allosteric effects in the enzyme. These structure-function analyses of AA-mediated PKM2 regulation shed light on the chemical requirements in the development of mechanism-based small-molecule modulators targeting the AA-binding pocket of PKM2 and provide broader insights into the regulatory mechanisms of complex allosteric enzymes.




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Evolution, expression, and substrate specificities of aldehyde oxidase enzymes in eukaryotes [Enzymology]

Aldehyde oxidases (AOXs) are a small group of enzymes belonging to the larger family of molybdo-flavoenzymes, along with the well-characterized xanthine oxidoreductase. The two major types of reactions that are catalyzed by AOXs are the hydroxylation of heterocycles and the oxidation of aldehydes to their corresponding carboxylic acids. Different animal species have different complements of AOX genes. The two extremes are represented in humans and rodents; whereas the human genome contains a single active gene (AOX1), those of rodents, such as mice, are endowed with four genes (Aox1-4), clustering on the same chromosome, each encoding a functionally distinct AOX enzyme. It still remains enigmatic why some species have numerous AOX enzymes, whereas others harbor only one functional enzyme. At present, little is known about the physiological relevance of AOX enzymes in humans and their additional forms in other mammals. These enzymes are expressed in the liver and play an important role in the metabolisms of drugs and other xenobiotics. In this review, we discuss the expression, tissue-specific roles, and substrate specificities of the different mammalian AOX enzymes and highlight insights into their physiological roles.




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The heme-regulatory motifs of heme oxygenase-2 contribute to the transfer of heme to the catalytic site for degradation [Protein Structure and Folding]

Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis.




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An enzyme-based protocol for cell-free synthesis of nature-identical capsular oligosaccharides from Actinobacillus pleuropneumoniae serotype 1 [Enzymology]

Actinobacillus pleuropneumoniae (App) is the etiological agent of acute porcine pneumonia and responsible for severe economic losses worldwide. The capsule polymer of App serotype 1 (App1) consists of [4)-GlcNAc-β(1,6)-Gal-α-1-(PO4-] repeating units that are O-acetylated at O-6 of the GlcNAc. It is a major virulence factor and was used in previous studies in the successful generation of an experimental glycoconjugate vaccine. However, the application of glycoconjugate vaccines in the animal health sector is limited, presumably because of the high costs associated with harvesting the polymer from pathogen culture. Consequently, here we exploited the capsule polymerase Cps1B of App1 as an in vitro synthesis tool and an alternative for capsule polymer provision. Cps1B consists of two catalytic domains, as well as a domain rich in tetratricopeptide repeats (TPRs). We compared the elongation mechanism of Cps1B with that of a ΔTPR truncation (Cps1B-ΔTPR). Interestingly, the product profiles displayed by Cps1B suggested processive elongation of the nascent polymer, whereas Cps1B-ΔTPR appeared to work in a more distributive manner. The dispersity of the synthesized products could be reduced by generating single-action transferases and immobilizing them on individual columns, separating the two catalytic activities. Furthermore, we identified the O-acetyltransferase Cps1D of App1 and used it to modify the polymers produced by Cps1B. Two-dimensional NMR analyses of the products revealed O-acetylation levels identical to those of polymer harvested from App1 culture supernatants. In conclusion, we have established a protocol for the pathogen-free in vitro synthesis of tailored, nature-identical App1 capsule polymers.




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Structural and mutational analyses of the bifunctional arginine dihydrolase and ornithine cyclodeaminase AgrE from the cyanobacterium Anabaena [Enzymology]

In cyanobacteria, metabolic pathways that use the nitrogen-rich amino acid arginine play a pivotal role in nitrogen storage and mobilization. The N-terminal domains of two recently identified bacterial enzymes: ArgZ from Synechocystis and AgrE from Anabaena, have been found to contain an arginine dihydrolase. This enzyme provides catabolic activity that converts arginine to ornithine, resulting in concomitant release of CO2 and ammonia. In Synechocystis, the ArgZ-mediated ornithine–ammonia cycle plays a central role in nitrogen storage and remobilization. The C-terminal domain of AgrE contains an ornithine cyclodeaminase responsible for the formation of proline from ornithine and ammonia production, indicating that AgrE is a bifunctional enzyme catalyzing two sequential reactions in arginine catabolism. Here, the crystal structures of AgrE in three different ligation states revealed that it has a tetrameric conformation, possesses a binding site for the arginine dihydrolase substrate l-arginine and product l-ornithine, and contains a binding site for the coenzyme NAD(H) required for ornithine cyclodeaminase activity. Structure–function analyses indicated that the structure and catalytic mechanism of arginine dihydrolase in AgrE are highly homologous with those of a known bacterial arginine hydrolase. We found that in addition to other active-site residues, Asn-71 is essential for AgrE's dihydrolase activity. Further analysis suggested the presence of a passage for substrate channeling between the two distinct AgrE active sites, which are situated ∼45 Å apart. These results provide structural and functional insights into the bifunctional arginine dihydrolase–ornithine cyclodeaminase enzyme AgrE required for arginine catabolism in Anabaena.




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Detailed analyses of the crucial functions of Zn transporter proteins in alkaline phosphatase activation [Enzymology]

Numerous zinc ectoenzymes are metalated by zinc and activated in the compartments of the early secretory pathway before reaching their destination. Zn transporter (ZNT) proteins located in these compartments are essential for ectoenzyme activation. We have previously reported that ZNT proteins, specifically ZNT5–ZNT6 heterodimers and ZNT7 homodimers, play critical roles in the activation of zinc ectoenzymes, such as alkaline phosphatases (ALPs), by mobilizing cytosolic zinc into these compartments. However, this process remains incompletely understood. Here, using genetically-engineered chicken DT40 cells, we first determined that Zrt/Irt-like protein (ZIP) transporters that are localized to the compartments of the early secretory pathway play only a minor role in the ALP activation process. These transporters included ZIP7, ZIP9, and ZIP13, performing pivotal functions in maintaining cellular homeostasis by effluxing zinc out of the compartments. Next, using purified ALP proteins, we showed that zinc metalation on ALP produced in DT40 cells lacking ZNT5–ZNT6 heterodimers and ZNT7 homodimers is impaired. Finally, by genetically disrupting both ZNT5 and ZNT7 in human HAP1 cells, we directly demonstrated that the tissue-nonspecific ALP-activating functions of both ZNT complexes are conserved in human cells. Furthermore, using mutant HAP1 cells, we uncovered a previously-unrecognized and unique spatial regulation of ZNT5–ZNT6 heterodimer formation, wherein ZNT5 recruits ZNT6 to the Golgi apparatus to form the heterodimeric complex. These findings fill in major gaps in our understanding of the molecular mechanisms underlying zinc ectoenzyme activation in the compartments of the early secretory pathway.




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Reduction of protein phosphatase 2A (PP2A) complexity reveals cellular functions and dephosphorylation motifs of the PP2A/B'{delta} holoenzyme [Enzymology]

Protein phosphatase 2A (PP2A) is a large enzyme family responsible for most cellular Ser/Thr dephosphorylation events. PP2A substrate specificity, localization, and regulation by second messengers rely on more than a dozen regulatory subunits (including B/R2, B'/R5, and B″/R3), which form the PP2A heterotrimeric holoenzyme by associating with a dimer comprising scaffolding (A) and catalytic (C) subunits. Because of partial redundancy and high endogenous expression of PP2A holoenzymes, traditional approaches of overexpressing, knocking down, or knocking out PP2A regulatory subunits have yielded only limited insights into their biological roles and substrates. To this end, here we sought to reduce the complexity of cellular PP2A holoenzymes. We used tetracycline-inducible expression of pairs of scaffolding and regulatory subunits with complementary charge-reversal substitutions in their interaction interfaces. For each of the three regulatory subunit families, we engineered A/B charge–swap variants that could bind to one another, but not to endogenous A and B subunits. Because endogenous Aα was targeted by a co-induced shRNA, endogenous B subunits were rapidly degraded, resulting in expression of predominantly a single PP2A heterotrimer composed of the A/B charge–swap pair and the endogenous catalytic subunit. Using B'δ/PPP2R5D, we show that PP2A complexity reduction, but not PP2A overexpression, reveals a role of this holoenzyme in suppression of extracellular signal–regulated kinase signaling and protein kinase A substrate dephosphorylation. When combined with global phosphoproteomics, the PP2A/B'δ reduction approach identified consensus dephosphorylation motifs in its substrates and suggested that residues surrounding the phosphorylation site play roles in PP2A substrate specificity.




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Structure of an ancestral mammalian family 1B1 cytochrome P450 with increased thermostability [Enzymology]

Mammalian cytochrome P450 enzymes often metabolize many pharmaceuticals and other xenobiotics, a feature that is valuable in a biotechnology setting. However, extant P450 enzymes are typically relatively unstable, with T50 values of ∼30–40 °C. Reconstructed ancestral cytochrome P450 enzymes tend to have variable substrate selectivity compared with related extant forms, but they also have higher thermostability and therefore may be excellent tools for commercial biosynthesis of important intermediates, final drug molecules, or drug metabolites. The mammalian ancestor of the cytochrome P450 1B subfamily was herein characterized structurally and functionally, revealing differences from the extant human CYP1B1 in ligand binding, metabolism, and potential molecular contributors to its thermostability. Whereas extant human CYP1B1 has one molecule of α-naphthoflavone in a closed active site, we observed that subtle amino acid substitutions outside the active site in the ancestor CYP1B enzyme yielded an open active site with four ligand copies. A structure of the ancestor with 17β-estradiol revealed only one molecule in the active site, which still had the same open conformation. Detailed comparisons between the extant and ancestor forms revealed increases in electrostatic and aromatic interactions between distinct secondary structure elements in the ancestral forms that may contribute to their thermostability. To the best of our knowledge, this represents the first structural evaluation of a reconstructed ancestral cytochrome P450, revealing key features that appear to contribute to its thermostability.




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Specificity and affinity of the N-terminal residues in staphylocoagulase in binding to prothrombin [Computational Biology]

In Staphylococcus aureus–caused endocarditis, the pathogen secretes staphylocoagulase (SC), thereby activating human prothrombin (ProT) and evading immune clearance. A previous structural comparison of the SC(1–325) fragment bound to thrombin and its inactive precursor prethrombin 2 has indicated that SC activates ProT by inserting its N-terminal dipeptide Ile1-Val2 into the ProT Ile16 pocket, forming a salt bridge with ProT's Asp194, thereby stabilizing the active conformation. We hypothesized that these N-terminal SC residues modulate ProT binding and activation. Here, we generated labeled SC(1–246) as a probe for competitively defining the affinities of N-terminal SC(1–246) variants preselected by modeling. Using ProT(R155Q,R271Q,R284Q) (ProTQQQ), a variant refractory to prothrombinase- or thrombin-mediated cleavage, we observed variant affinities between ∼1 and 650 nm and activation potencies ranging from 1.8-fold that of WT SC(1–246) to complete loss of function. Substrate binding to ProTQQQ caused allosteric tightening of the affinity of most SC(1–246) variants, consistent with zymogen activation through occupation of the specificity pocket. Conservative changes at positions 1 and 2 were well-tolerated, with Val1-Val2, Ile1-Ala2, and Leu1-Val2 variants exhibiting ProTQQQ affinity and activation potency comparable with WT SC(1–246). Weaker binding variants typically had reduced activation rates, although at near-saturating ProTQQQ levels, several variants exhibited limiting rates similar to or higher than that of WT SC(1–246). The Ile16 pocket in ProTQQQ appears to favor nonpolar, nonaromatic residues at SC positions 1 and 2. Our results suggest that SC variants other than WT Ile1-Val2-Thr3 might emerge with similar ProT-activating efficiency.




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Processivity of dextransucrases synthesizing very-high-molar-mass dextran is mediated by sugar-binding pockets in domain V [Glycobiology and Extracellular Matrices]

The dextransucrase DSR-OK from the Gram-positive bacterium Oenococcus kitaharae DSM17330 produces a dextran of the highest molar mass reported to date (∼109 g/mol). In this study, we selected a recombinant form, DSR-OKΔ1, to identify molecular determinants involved in the sugar polymerization mechanism and that confer its ability to produce a very-high-molar-mass polymer. In domain V of DSR-OK, we identified seven putative sugar-binding pockets characteristic of glycoside hydrolase 70 (GH70) glucansucrases that are known to be involved in glucan binding. We investigated their role in polymer synthesis through several approaches, including monitoring of dextran synthesis, affinity assays, sugar binding pocket deletions, site-directed mutagenesis, and construction of chimeric enzymes. Substitution of only two stacking aromatic residues in two consecutive sugar-binding pockets (variant DSR-OKΔ1-Y1162A-F1228A) induced quasi-complete loss of very-high-molar-mass dextran synthesis, resulting in production of only 10–13 kg/mol polymers. Moreover, the double mutation completely switched the semiprocessive mode of DSR-OKΔ1 toward a distributive one, highlighting the strong influence of these pockets on enzyme processivity. Finally, the position of each pocket relative to the active site also appeared to be important for polymer elongation. We propose that sugar-binding pockets spatially closer to the catalytic domain play a major role in the control of processivity. A deep structural characterization, if possible with large-molar-mass sugar ligands, would allow confirming this hypothesis.




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The Escherichia coli cellulose synthase subunit G (BcsG) is a Zn2+-dependent phosphoethanolamine transferase [Glycobiology and Extracellular Matrices]

Bacterial biofilms are cellular communities that produce an adherent matrix. Exopolysaccharides are key structural components of this matrix and are required for the assembly and architecture of biofilms produced by a wide variety of microorganisms. The human bacterial pathogens Escherichia coli and Salmonella enterica produce a biofilm matrix composed primarily of the exopolysaccharide phosphoethanolamine (pEtN) cellulose. Once thought to be composed of only underivatized cellulose, the pEtN modification present in these matrices has been implicated in the overall architecture and integrity of the biofilm. However, an understanding of the mechanism underlying pEtN derivatization of the cellulose exopolysaccharide remains elusive. The bacterial cellulose synthase subunit G (BcsG) is a predicted inner membrane–localized metalloenzyme that has been proposed to catalyze the transfer of the pEtN group from membrane phospholipids to cellulose. Here we present evidence that the C-terminal domain of BcsG from E. coli (EcBcsGΔN) functions as a phosphoethanolamine transferase in vitro with substrate preference for cellulosic materials. Structural characterization of EcBcsGΔN revealed that it belongs to the alkaline phosphatase superfamily, contains a Zn2+ ion at its active center, and is structurally similar to characterized enzymes that confer colistin resistance in Gram-negative bacteria. Informed by our structural studies, we present a functional complementation experiment in E. coli AR3110, indicating that the activity of the BcsG C-terminal domain is essential for integrity of the pellicular biofilm. Furthermore, our results established a similar but distinct active-site architecture and catalytic mechanism shared between BcsG and the colistin resistance enzymes.




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A Legionella effector kinase is activated by host inositol hexakisphosphate [Enzymology]

The transfer of a phosphate from ATP to a protein substrate, a modification known as protein phosphorylation, is catalyzed by protein kinases. Protein kinases play a crucial role in virtually every cellular activity. Recent studies of atypical protein kinases have highlighted the structural similarity of the kinase superfamily despite notable differences in primary amino acid sequence. Here, using a bioinformatics screen, we searched for putative protein kinases in the intracellular bacterial pathogen Legionella pneumophila and identified the type 4 secretion system effector Lpg2603 as a remote member of the protein kinase superfamily. Employing an array of biochemical and structural biology approaches, including in vitro kinase assays and isothermal titration calorimetry, we show that Lpg2603 is an active protein kinase with several atypical structural features. Importantly, we found that the eukaryote-specific host signaling molecule inositol hexakisphosphate (IP6) is required for Lpg2603 kinase activity. Crystal structures of Lpg2603 in the apo-form and when bound to IP6 revealed an active-site rearrangement that allows for ATP binding and catalysis. Our results on the structure and activity of Lpg2603 reveal a unique mode of regulation of a protein kinase, provide the first example of a bacterial kinase that requires IP6 for its activation, and may aid future work on the function of this effector during Legionella pathogenesis.




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NAD+ biosynthesis in bacteria is controlled by global carbon/nitrogen levels via PII signaling [Microbiology]

NAD+ is a central metabolite participating in core metabolic redox reactions. The prokaryotic NAD synthetase enzyme NadE catalyzes the last step of NAD+ biosynthesis, converting nicotinic acid adenine dinucleotide (NaAD) to NAD+. Some members of the NadE family use l-glutamine as a nitrogen donor and are named NadEGln. Previous gene neighborhood analysis has indicated that the bacterial nadE gene is frequently clustered with the gene encoding the regulatory signal transduction protein PII, suggesting a functional relationship between these proteins in response to the nutritional status and the carbon/nitrogen ratio of the bacterial cell. Here, using affinity chromatography, bioinformatics analyses, NAD synthetase activity, and biolayer interferometry assays, we show that PII and NadEGln physically interact in vitro, that this complex relieves NadEGln negative feedback inhibition by NAD+. This mechanism is conserved in distantly related bacteria. Of note, the PII protein allosteric effector and cellular nitrogen level indicator 2-oxoglutarate (2-OG) inhibited the formation of the PII-NadEGln complex within a physiological range. These results indicate an interplay between the levels of ATP, ADP, 2-OG, PII-sensed glutamine, and NAD+, representing a metabolic hub that may balance the levels of core nitrogen and carbon metabolites. Our findings support the notion that PII proteins act as a dissociable regulatory subunit of NadEGln, thereby enabling the control of NAD+ biosynthesis according to the nutritional status of the bacterial cell.




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Impact of 1,N6-ethenoadenosine, a damaged ribonucleotide in DNA, on translesion synthesis and repair [Enzymology]

Incorporation of ribonucleotides into DNA can severely diminish genome integrity. However, how ribonucleotides instigate DNA damage is poorly understood. In DNA, they can promote replication stress and genomic instability and have been implicated in several diseases. We report here the impact of the ribonucleotide rATP and of its naturally occurring damaged analog 1,N6-ethenoadenosine (1,N6-ϵrA) on translesion synthesis (TLS), mediated by human DNA polymerase η (hpol η), and on RNase H2–mediated incision. Mass spectral analysis revealed that 1,N6-ϵrA in DNA generates extensive frameshifts during TLS, which can lead to genomic instability. Moreover, steady-state kinetic analysis of the TLS process indicated that deoxypurines (i.e. dATP and dGTP) are inserted predominantly opposite 1,N6-ϵrA. We also show that hpol η acts as a reverse transcriptase in the presence of damaged ribonucleotide 1,N6-ϵrA but has poor RNA primer extension activities. Steady-state kinetic analysis of reverse transcription and RNA primer extension showed that hpol η favors the addition of dATP and dGTP opposite 1,N6-ϵrA. We also found that RNase H2 recognizes 1,N6-ϵrA but has limited incision activity across from this lesion, which can lead to the persistence of this detrimental DNA adduct. We conclude that the damaged and unrepaired ribonucleotide 1,N6-ϵrA in DNA exhibits mutagenic potential and can also alter the reading frame in an mRNA transcript because 1,N6-ϵrA is incompletely incised by RNase H2.




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It takes two (Las1 HEPN endoribonuclease domains) to cut RNA correctly [RNA]

The ribosome biogenesis factor Las1 is an essential endoribonuclease that is well-conserved across eukaryotes and a newly established member of the higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain-containing nuclease family. HEPN nucleases participate in diverse RNA cleavage pathways and share a short HEPN nuclease motif (RφXXXH) important for RNA cleavage. Most HEPN nucleases participate in stress-activated RNA cleavage pathways; Las1 plays a fundamental role in processing pre-rRNA. Underscoring the significance of Las1 function in the cell, mutations in the human LAS1L (LAS1-like) gene have been associated with neurological dysfunction. Two juxtaposed HEPN nuclease motifs create Las1's composite nuclease active site, but the roles of the individual HEPN motif residues are poorly defined. Here using a combination of in vivo experiments in Saccharomyces cerevisiae and in vitro assays, we show that both HEPN nuclease motifs are required for Las1 nuclease activity and fidelity. Through in-depth sequence analysis and systematic mutagenesis, we determined the consensus HEPN motif in the Las1 subfamily and uncovered its canonical and specialized elements. Using reconstituted Las1 HEPN-HEPN' chimeras, we defined the molecular requirements for RNA cleavage. Intriguingly, both copies of the Las1 HEPN motif were important for nuclease function, revealing that both HEPN motifs participate in coordinating the RNA within the Las1 active site. We also established that conformational flexibility of the two HEPN domains is important for proper nuclease function. The results of our work reveal critical information about how dual HEPN domains come together to drive Las1-mediated RNA cleavage.




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Spectral and photochemical diversity of tandem cysteine cyanobacterial phytochromes [Plant Biology]

The atypical trichromatic cyanobacterial phytochrome NpTP1 from Nostoc punctiforme ATCC 29133 is a linear tetrapyrrole (bilin)-binding photoreceptor protein that possesses tandem-cysteine residues responsible for shifting its light-sensing maximum to the violet spectral region. Using bioinformatics and phylogenetic analyses, here we established that tandem-cysteine cyanobacterial phytochromes (TCCPs) compose a well-supported monophyletic phytochrome lineage distinct from prototypical red/far-red cyanobacterial phytochromes. To investigate the light-sensing diversity of this family, we compared the spectroscopic properties of NpTP1 (here renamed NpTCCP) with those of three phylogenetically diverged TCCPs identified in the draft genomes of Tolypothrix sp. PCC7910, Scytonema sp. PCC10023, and Gloeocapsa sp. PCC7513. Recombinant photosensory core modules of ToTCCP, ScTCCP, and GlTCCP exhibited violet-blue–absorbing dark-states consistent with dual thioether-linked phycocyanobilin (PCB) chromophores. Photoexcitation generated singly-linked photoproduct mixtures with variable ratios of yellow-orange and red-absorbing species. The photoproduct ratio was strongly influenced by pH and by mutagenesis of TCCP- and phytochrome-specific signature residues. Our experiments support the conclusion that both photoproduct species possess protonated 15E bilin chromophores, but differ in the ionization state of the noncanonical “second” cysteine sulfhydryl group. We found that the ionization state of this and other residues influences subsequent conformational change and downstream signal transmission. We also show that tandem-cysteine phytochromes present in eukaryotes possess similar amino acid substitutions within their chromophore-binding pocket, which tune their spectral properties in an analogous fashion. Taken together, our findings provide a roadmap for tailoring the wavelength specificity of plant phytochromes to optimize plant performance in diverse natural and artificial light environments.




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Crystallographic and kinetic analyses of the FdsBG subcomplex of the cytosolic formate dehydrogenase FdsABG from Cupriavidus necator [Molecular Biophysics]

Formate oxidation to carbon dioxide is a key reaction in one-carbon compound metabolism, and its reverse reaction represents the first step in carbon assimilation in the acetogenic and methanogenic branches of many anaerobic organisms. The molybdenum-containing dehydrogenase FdsABG is a soluble NAD+-dependent formate dehydrogenase and a member of the NADH dehydrogenase superfamily. Here, we present the first structure of the FdsBG subcomplex of the cytosolic FdsABG formate dehydrogenase from the hydrogen-oxidizing bacterium Cupriavidus necator H16 both with and without bound NADH. The structures revealed that the two iron-sulfur clusters, Fe4S4 in FdsB and Fe2S2 in FdsG, are closer to the FMN than they are in other NADH dehydrogenases. Rapid kinetic studies and EPR measurements of rapid freeze-quenched samples of the NADH reduction of FdsBG identified a neutral flavin semiquinone, FMNH•, not previously observed to participate in NADH-mediated reduction of the FdsABG holoenzyme. We found that this semiquinone forms through the transfer of one electron from the fully reduced FMNH−, initially formed via NADH-mediated reduction, to the Fe2S2 cluster. This Fe2S2 cluster is not part of the on-path chain of iron-sulfur clusters connecting the FMN of FdsB with the active-site molybdenum center of FdsA. According to the NADH-bound structure, the nicotinamide ring stacks onto the re-face of the FMN. However, NADH binding significantly reduced the electron density for the isoalloxazine ring of FMN and induced a conformational change in residues of the FMN-binding pocket that display peptide-bond flipping upon NAD+ binding in proper NADH dehydrogenases.