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Cytochrome c oxidase (CcO) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fea32+ and CuB1+, and suggests that a peroxide-bound state (Fea33+–O−–O−–CuB2+) rather than an O2-bound state (Fea32+–O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fea32+–O2, whereas Fea33+–O−–O−–CuB2+ is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Å resolution. A 1.70 Å Fe–O distance of the ferryl center could best be described as Fea34+ = O2−, not as Fea34+–OH−. The distance suggests an ∼800-cm−1 Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fea33+–O−–O−–CuB2+ state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.

Optic atrophy 1 (OPA1) is a dynamin protein that mediates mitochondrial fusion at the inner membrane. OPA1 is also necessary for maintaining the cristae and thus essential for supporting cellular energetics. OPA1 exists as membrane-anchored long form (L-OPA1) and short form (S-OPA1) that lacks the transmembrane region and is generated by cleavage of L-OPA1. Mitochondrial dysfunction and cellular stresses activate the inner membrane–associated zinc metallopeptidase OMA1 that cleaves L-OPA1, causing S-OPA1 accumulation. The prevailing notion has been that L-OPA1 is the functional form, whereas S-OPA1 is an inactive cleavage product in mammals, and that stress-induced OPA1 cleavage causes mitochondrial fragmentation and sensitizes cells to death. However, S-OPA1 contains all functional domains of dynamin proteins, suggesting that it has a physiological role. Indeed, we recently demonstrated that S-OPA1 can maintain cristae and energetics through its GTPase activity, despite lacking fusion activity. Here, applying oxidant insult that induces OPA1 cleavage, we show that cells unable to generate S-OPA1 are more sensitive to this stress under obligatory respiratory conditions, leading to necrotic death. These findings indicate that L-OPA1 and S-OPA1 differ in maintaining mitochondrial function. Mechanistically, we found that cells that exclusively express L-OPA1 generate more superoxide and are more sensitive to Ca2+-induced mitochondrial permeability transition, suggesting that S-OPA1, and not L-OPA1, protects against cellular stress. Importantly, silencing of OMA1 expression increased oxidant-induced cell death, indicating that stress-induced OPA1 cleavage supports cell survival. Our findings suggest that S-OPA1 generation by OPA1 cleavage is a survival mechanism in stressed cells.

pncRNA-D is an irradiation-induced 602-nt long noncoding RNA transcribed from the promoter region of the cyclin D1 (CCND1) gene. CCND1 expression is predicted to be inhibited through an interplay between pncRNA-D and RNA-binding protein TLS/FUS. Because the pncRNA-D–TLS interaction is essential for pncRNA-D–stimulated CCND1 inhibition, here we studied the possible role of RNA modification in this interaction in HeLa cells. We found that osmotic stress induces pncRNA-D by recruiting RNA polymerase II to its promoter. pncRNA-D was highly m6A-methylated in control cells, but osmotic stress reduced the methylation and also arginine methylation of TLS in the nucleus. Knockdown of the m6A modification enzyme methyltransferase-like 3 (METTL3) prolonged the half-life of pncRNA-D, and among the known m6A recognition proteins, YTH domain-containing 1 (YTHDC1) was responsible for binding m6A of pncRNA-D. Knockdown of METTL3 or YTHDC1 also enhanced the interaction of pncRNA-D with TLS, and results from RNA pulldown assays implicated YTHDC1 in the inhibitory effect on the TLS–pncRNA-D interaction. CRISPR/Cas9-mediated deletion of candidate m6A site decreased the m6A level in pncRNA-D and altered its interaction with the RNA-binding proteins. Of note, a reduction in the m6A modification arrested the cell cycle at the G0/G1 phase, and pncRNA-D knockdown partially reversed this arrest. Moreover, pncRNA-D induction in HeLa cells significantly suppressed cell growth. Collectively, these findings suggest that m6A modification of the long noncoding RNA pncRNA-D plays a role in the regulation of CCND1 gene expression and cell cycle progression.

tRNAs universally carry a CCA nucleotide triplet at their 3'-ends. In eukaryotes, the CCA is added post-transcriptionally by the CCA-adding enzyme (CAE). The mitochondrion of the parasitic protozoan Trypanosoma brucei lacks tRNA genes and therefore imports all of its tRNAs from the cytosol. This has generated interest in the tRNA modifications and their distribution in this organism, including how CCA is added to tRNAs. Here, using a BLAST search for genes encoding putative CAE proteins in T. brucei, we identified a single ORF, Tb927.9.8780, as a potential candidate. Knockdown of this putative protein, termed TbCAE, resulted in the accumulation of truncated tRNAs, abolished translation, and inhibited both total and mitochondrial CCA-adding activities, indicating that TbCAE is located both in the cytosol and mitochondrion. However, mitochondrially localized tRNAs were much less affected by the TbCAE ablation than the other tRNAs. Complementation assays revealed that the N-terminal 10 amino acids of TbCAE are dispensable for its activity and mitochondrial localization and that deletion of 10 further amino acids abolishes both. A growth arrest caused by the TbCAE knockdown was rescued by the expression of the cytosolic isoform of yeast CAE, even though it was not imported into mitochondria. This finding indicated that the yeast enzyme complements the essential function of TbCAE by adding CCA to the primary tRNA transcripts. Of note, ablation of the mitochondrial TbCAE activity, which likely has a repair function, only marginally affected growth.

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.

Site-specific arrest of RNA polymerases (RNAPs) is fundamental to several technologies that assess RNA structure and function. Current in vitro transcription “roadblocking” approaches inhibit transcription elongation by blocking RNAP with a protein bound to the DNA template. One limitation of protein-mediated transcription roadblocking is that it requires inclusion of a protein factor extrinsic to the minimal in vitro transcription reaction. In this work, we developed a chemical approach for halting transcription by Escherichia coli RNAP. We first established a sequence-independent method for site-specific incorporation of chemical lesions into dsDNA templates by sequential PCR and translesion synthesis. We then show that interrupting the transcribed DNA strand with an internal desthiobiotin-triethylene glycol modification or 1,N6-etheno-2'-deoxyadenosine base efficiently and stably halts Escherichia coli RNAP transcription. By encoding an intrinsic stall site within the template DNA, our chemical transcription roadblocking approach enables display of nascent RNA molecules from RNAP in a minimal in vitro transcription reaction.

The arrangement of functionally-related genes in operons is a fundamental element of how genetic information is organized in prokaryotes. This organization ensures coordinated gene expression by co-transcription. Often, however, alternative genetic responses to specific stress conditions demand the discoordination of operon expression. During cold temperature stress, accumulation of the gene encoding the sole Asp–Glu–Ala–Asp (DEAD)-box RNA helicase in Synechocystis sp. PCC 6803, crhR (slr0083), increases 15-fold. Here, we show that crhR is expressed from a dicistronic operon with the methylthiotransferase rimO/miaB (slr0082) gene, followed by rapid processing of the operon transcript into two monocistronic mRNAs. This cleavage event is required for and results in destabilization of the rimO transcript. Results from secondary structure modeling and analysis of RNase E cleavage of the rimO–crhR transcript in vitro suggested that CrhR plays a role in enhancing the rate of the processing in an auto-regulatory manner. Moreover, two putative small RNAs are generated from additional processing, degradation, or both of the rimO transcript. These results suggest a role for the bacterial RNA helicase CrhR in RNase E-dependent mRNA processing in Synechocystis and expand the known range of organisms possessing small RNAs derived from processing of mRNA transcripts.

Kainate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are two major, closely related receptor subtypes in the glutamate ion channel family. Excessive activities of these receptors have been implicated in a number of central nervous system diseases. Designing potent and selective antagonists of these receptors, especially of kainate receptors, is useful for developing potential treatment strategies for these neurological diseases. Here, we report on two RNA aptamers designed to individually inhibit kainate and AMPA receptors. To improve the biostability of these aptamers, we also chemically modified these aptamers by substituting their 2'-OH group with 2'-fluorine. These 2'-fluoro aptamers, FB9s-b and FB9s-r, were markedly resistant to RNase-catalyzed degradation, with a half-life of ∼5 days in rat cerebrospinal fluid or serum-containing medium. Furthermore, FB9s-r blocked AMPA receptor activity. Aptamer FB9s-b selectively inhibited GluK1 and GluK2 kainate receptor subunits, and also GluK1/GluK5 and GluK2/GluK5 heteromeric kainate receptors with equal potency. This inhibitory profile makes FB9s-b a powerful template for developing tool molecules and drug candidates for treatment of neurological diseases involving excessive activities of the GluK1 and GluK2 subunits.

K. D. Cherednichenko, Yu. Yu. Ershova, A. V. Kiselev and S. N. Naboko
Trans. Moscow Math. Soc. 80 (2020), 251-294.
Abstract, references and article information

A. M. Savchuk and I. V. Sadovnichaya
Trans. Moscow Math. Soc. 80 (2020), 235-250.
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I. V. Astashova, D. A. Lashin and A. V. Filinovskii
Trans. Moscow Math. Soc. 80 (2020), 221-234.
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A. A. Vladimirov
Trans. Moscow Math. Soc. 80 (2020), 211-219.
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I. A. Sheipak and T. A. Garmanova
Trans. Moscow Math. Soc. 80 (2020), 189-210.
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V. V. Vlasov and N. A. Rautian
Trans. Moscow Math. Soc. 80 (2020), 169-188.
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N. F. Valeev, Ya. T. Sultanaev and É. A. Nazirova
Trans. Moscow Math. Soc. 80 (2020), 153-167.
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K. A. Mirzoev and T. A. Safonova
Trans. Moscow Math. Soc. 80 (2020), 133-151.
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V. A. Sadovnichii, Ya. T. Sultanaev and A. M. Akhtyamov
Trans. Moscow Math. Soc. 80 (2020), 123-131.
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Trans. Moscow Math. Soc. 80 (2020), 113-122.
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A. G. Sergeev and Kh. A. Khachatryan
Trans. Moscow Math. Soc. 80 (2020), 95-111.
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V. V. Ryzhikov
Trans. Moscow Math. Soc. 80 (2020), 83-94.
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S. Yu. Orevkov
Trans. Moscow Math. Soc. 80 (2020), 73-81.
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S. A. Kashchenko
Trans. Moscow Math. Soc. 80 (2020), 53-71.
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S. A. Nazarov
Trans. Moscow Math. Soc. 80 (2020), 1-51.
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Prótese auditiva ancorada em osso não emite um som como o aparelho convencional. Seu diferencial é vibrar o osso da cabeça.

The post SUS vai oferecer aparelho de última geração para tipo de perda auditiva até então sem tratamento appeared first on Saúde Próspera.

Todo mundo quer ter um sorriso bonito. Justamente por isso, a ideia de perder um ou mais dentes deixa qualquer pessoa desesperada.

The post Saiba como ter um sorriso perfeito appeared first on Saúde Próspera.

Tratamento genético foi testado em Layla Richards que estava desenganada pelos médicos. Especialistas ressaltam que os resultados são iniciais e podem não ocorrer em outros pacientes.

The post Terapia inédita reverte leucemia incurável em bebê de 1 ano appeared first on Saúde Próspera.

Exame poderá detectar a doença na fase inicial. Pesquisadores da Faculdade de Medicina Osteopática da Universidade de Rowan, nos Estados Unidos, afirmam que estão perto de desenvolver um exame de sangue para detectar Alzheimer com precisão, o que dar...

The post Teste de sangue para detectar Alzheimer está próximo da realidade appeared first on Saúde Próspera.

Unha encravada: quem teve jamais quer repetir a experiência. Os que nunca passaram pela situação, tremem com a ideia de sentir aquela dor de que só ouvem sobre nos relatos.

The post Unha encravada: Como evitar e desencravar appeared first on Saúde Próspera.

Aos primeiros sinais de visão embaçada, as hipóteses mais frequentes sempre são miopia, astigmatismo, hipermetropia. Mas esses sintomas podem indicar outra doença ocular chamada ceratocone - uma deformidade progressiva da córnea, que assume o formato...

The post Visão embaçada e distorcida nem sempre é miopia: fique atento aos sinais do ceratocone appeared first on Saúde Próspera.

Tem tomado seus cuidados com a pele? Neste artigo vamos ensinar a fazer limpeza de pele caseira. Conhecer  os benefícios para limpeza de pele. Conheça o passo a passo a…

The post Cuidados com a pele – Aprenda a fazer limpeza de pele caseira appeared first on Saúde Próspera.

Com que roupa eu vou? Todos os dias nós, mulheres, enfrentamos o dilema de decidir o que vestir. Veja algumas dicas para lhe ajudar a escolher qual roupa usar… A…

The post Com que roupa eu vou? Dicas de qual roupa usar appeared first on Saúde Próspera.

A cirurgia plástica é a área da medicina responsável pela reparação dos defeitos estéticos. Os problemas estéticos podem ser congênitos, ou seja, que já estão presentes no nascimento ou adquiridos…

The post Cirurgia Plástica não tem idade appeared first on Saúde Próspera.

O que é Candidíase? Candidíase, é uma infecção sistêmica causada pelo fungos da Candida albicans. A Candida albicans é um tipo de fungo (levedura) que vive em harmonia no organismo,…

The post Candidíase – Conheça as causas, sintomas e tratamentos appeared first on Saúde Próspera.

A. Knightly and C. Li
Memoirs of the AMS 224 (2012).
Abstract, references and article information

Publication Date: Apr 10 2020 The SEC will withdraw the existing approval order and the fund will become subject to the requirements of Rule 6c-11 and Nasdaq Rule 5704....

Publication Date: Apr 10 2020 Yes. According to the SEC, once an ETF becomes eligible to operate under Rule 6c-11 and elects to list on Nasdaq under Nasdaq Rule 5704, the existing order related to that fund (and all other funds under that exemptive order) will be rescinded. Once a fund is listed under Nasdaq Rule 5704, it will not be able to relist under Nasdaq Rule 5705(b) (Index Fund Shares) or Nasdaq Rule 5735 (Managed Fund Shares) unless a new exemptive relief order is obtained from the SEC....

Publication Date: Apr 10 2020 Funds listed under Nasdaq Rule 5704 are required to submit an annual certification regarding the funds compliance with Rule 6c-11 during the most recent fiscal year. The certification is required within 30 calendar days of a fund’s fiscal year end. The certification can be found here....

Publication Date: Apr 10 2020 On or before December 22, 2020, all ETFs that meet the definition of "Exchange Traded Fund" in Nasdaq Rule 5704(a)(1)(A) will need to be compliant with Rule 6c-11. If it is determined that an ETF no longer complies with Rule 6c-11 and therefore no longer complies Nasdaq Rule 5704, Nasdaq will generally issue a letter of deficiency. The ETF will generally be given 45 days to submit a plan to regain compliance. If the plan is accepted, Nasdaq Staff can grant an...

Publication Date: Apr 10 2020 ETFs that meet the definition of “Exchange Traded Fund” in Nasdaq Rule 5704(a)(1)(A) are eligible to be considered for listing pursuant to Nasdaq Rule 5704. ETFs that are excluded from operating pursuant to Rule 6c-11 under the Investment Company Act of 1940 are not eligible to list under Nasdaq Rule 5704....

Publication Date: Apr 10 2020 New Fund Launches In addition to completing the Listing Application, new funds are required to complete a certification prior to receiving approval of an initial listing application. The certification can be found here. Listing Transfers In addition to completing the Listing Application, funds switching from another market to Nasdaq are required to complete a certification regarding compliance with SEC Rule 6c-11. The certification must be completed prior to...

Publication Date: May 4 2020 On May 1, 2020, Nasdaq adopted Rule 5636T, operative through, and including, June 30, 2020, to provide listed companies with a temporary exception from certain shareholder approval requirements. A Company must submit an application to Nasdaq’s Listing Qualifications Department demonstrating that the transaction satisfies the requirements in Rule 5636T and must provide the Notification Form: Listing of Additional Shares (“LAS Form”) required by...

Web hosting behemoth GoDaddy just filed a data breach notification with the US state of California.

The leak exposed millions of records with full names, emails, user conversations, payment logs, and IP addresses dating back to March.

Researchers have poked another small hole in air gapped security by showing how the electronics inside computer power supply units (PSUs) can be turned into covert data transmission devices.

Firefox's latest version is out, with new password management features and a raft of security fixes.

Five alleged members of hacking group InfinityBlack got some unexpected visitors last week when Polish law enforcement arrested them.

In April, the company yanked 1,887 misleading accounts, pages and groups tied to eight influencer networks building fake engagement.