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1.
Nat Commun ; 15(1): 1382, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38360885

RESUMO

Cotranslational protein folding depends on general chaperones that engage highly diverse nascent chains at the ribosomes. Here we discover a dedicated ribosome-associated chaperone, Chp1, that rewires the cotranslational folding machinery to assist in the challenging biogenesis of abundantly expressed eukaryotic translation elongation factor 1A (eEF1A). Our results indicate that during eEF1A synthesis, Chp1 is recruited to the ribosome with the help of the nascent polypeptide-associated complex (NAC), where it safeguards eEF1A biogenesis. Aberrant eEF1A production in the absence of Chp1 triggers instant proteolysis, widespread protein aggregation, activation of Hsf1 stress transcription and compromises cellular fitness. The expression of pathogenic eEF1A2 variants linked to epileptic-dyskinetic encephalopathy is protected by Chp1. Thus, eEF1A is a difficult-to-fold protein that necessitates a biogenesis pathway starting with dedicated folding factor Chp1 at the ribosome to protect the eukaryotic cell from proteostasis collapse.


Assuntos
Proteínas de Ligação ao Cálcio , Chaperonas Moleculares , Fator 1 de Elongação de Peptídeos , Dobramento de Proteína , Ribossomos , Biossíntese de Proteínas , Proteostase , Ribossomos/genética , Ribossomos/metabolismo , Humanos , Proteínas de Ligação ao Cálcio/metabolismo , Chaperonas Moleculares/metabolismo , Fator 1 de Elongação de Peptídeos/metabolismo
2.
Seizure ; 109: 83-91, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37276778

RESUMO

BACKGROUND: Across Europe, there are differences regarding driving restrictions for patients with epilepsies and seizures. In the light of increasing mobility, knowledge about those different regulations is of high importance for counseling patients, and physicians. METHODS: A structured online survey was sent to the official representatives of the different European ILAE chapters, asking for the local driving restrictions for patients with epilepsies, first seizures, syncopes, and psychogenic non-epileptic seizures. RESULTS: The survey was sent to 38 chapters or representatives of 47 European Countries. 33 chapters answered. The majority of countries require 1 year of seizure-freedom for the ability to drive (Group 1, former categories A, B, B + E, F, G. H, K, L, and P; driving license which authorizes its holder to drive vehicle classes categories of the motor vehicle), usually with the need to continue antiseizure medication (ASM). Some countries have much stricter regulations before allowing for driving. Legal regulations after a first unprovoked seizure differ between 6 months for Group 1 license holders in most European countries, and one year in Luxembourg and Malta. In Serbia, there is no legal regulation for this special situation. The situation after a first seizure is even more complex for Group 2 license holders (former categories C1, C1+E, C, C + E, D1, D1+E, D, D + E). CONCLUSION: Knowledge of the different recommendations of the individual European countries is of high relevance in the counseling of epilepsy patients. Europe-wide regulations, e.g. following the IBE-recommendations are needed to facilitate the patients' situation.


Assuntos
Condução de Veículo , Epilepsia , Humanos , Epilepsia/tratamento farmacológico , Epilepsia/epidemiologia , Epilepsia/psicologia , Convulsões/psicologia , Europa (Continente) , Inquéritos e Questionários
3.
Methods Enzymol ; 684: 1-38, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37230585

RESUMO

The processing, membrane targeting and folding of newly synthesized polypeptides is closely linked to their synthesis at the ribosome. A network of enzymes, chaperones and targeting factors engages ribosome-nascent chain complexes (RNCs) to support these maturation processes. Exploring the modes of action of this machinery is critical for our understanding of functional protein biogenesis. Selective ribosome profiling (SeRP) is a powerful method for interrogating co-translational interactions of maturation factors with RNCs. It provides proteome-wide information on the factor's nascent chain interactome, the timing of factor binding and release during the progress of translation of individual nascent chain species, and the mechanisms and features controlling factor engagement. SeRP is based on the combination of two ribosome profiling (RP) experiments performed on the same cell population. In one experiment the ribosome-protected mRNA footprints of all translating ribosomes of the cell are sequenced (total translatome), while the other experiment detects only the ribosome footprints of the subpopulation of ribosomes engaged by the factor of interest (selected translatome). The codon-specific ratio of ribosome footprint densities from selected over total translatome reports on the factor enrichment at specific nascent chains. In this chapter, we provide a detailed SeRP protocol for mammalian cells. The protocol includes instructions on cell growth and cell harvest, stabilization of factor-RNC interactions, nuclease digest and purification of (factor-engaged) monosomes, as well as preparation of cDNA libraries from ribosome footprint fragments and deep sequencing data analysis. Purification protocols of factor-engaged monosomes and experimental results are exemplified for the human ribosomal tunnel exit-binding factor Ebp1 and chaperone Hsp90, but the protocols are readily adaptable to other co-translationally acting mammalian factors.


Assuntos
Perfil de Ribossomos , Ribossomos , Animais , Humanos , Ribossomos/metabolismo , Chaperonas Moleculares/química , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Peptídeos/química , Sequência de Bases , Biossíntese de Proteínas , Mamíferos/genética
4.
Epilepsia ; 64(3): 567-585, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36266921

RESUMO

Older adults represent a highly heterogeneous population, with multiple diverse subgroups. Therefore, an individualized approach to treatment is essential to meet the needs of each unique subgroup. Most comparative studies focusing on treatment of epilepsy in older adults have found that levetiracetam has the best chance of long-term seizure freedom. However, there is a lack of studies investigating other newer generation antiseizure medications (ASMs). Although a number of randomized clinical trials have been performed on older adults with epilepsy, the number of participants studied was generally small, and they only investigated short-term efficacy and tolerability. Quality of life as an outcome is often missing but is necessary to understand the effectiveness and possible side effects of treatment. Prognosis needs to move beyond the focus on seizure control to long-term patient-centered outcomes. Dosing studies with newer generation ASMs are needed to understand which treatments are the best in the older adults with different comorbidities. In particular, more high-level evidence is required for older adults with Alzheimer's disease with epilepsy and status epilepticus. Future treatment studies should use greater homogeneity in the inclusion criteria to allow for clearer findings that can be comparable with other studies to build the existing treatment evidence base.


Assuntos
Anticonvulsivantes , Epilepsia , Humanos , Idoso , Anticonvulsivantes/uso terapêutico , Qualidade de Vida , Epilepsia/tratamento farmacológico , Levetiracetam/uso terapêutico , Convulsões/tratamento farmacológico
5.
Cell Rep ; 41(10): 111776, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36476862

RESUMO

The chaperone SecB has been implicated in de novo protein folding and translocation across the membrane, but it remains unclear which nascent polypeptides SecB binds, when during translation SecB acts, how SecB function is coordinated with other chaperones and targeting factors, and how polypeptide engagement contributes to protein biogenesis. Using selective ribosome profiling, we show that SecB binds many nascent cytoplasmic and translocated proteins generally late during translation and controlled by the chaperone trigger factor. Revealing an uncharted role in co-translational translocation, inner membrane proteins (IMPs) are the most prominent nascent SecB interactors. Unlike other substrates, IMPs are bound early during translation, following the membrane targeting by the signal recognition particle. SecB remains bound until translation is terminated, and contributes to membrane insertion. Our study establishes a role of SecB in the co-translational maturation of proteins from all cellular compartments and functionally implicates cytosolic chaperones in membrane protein biogenesis.


Assuntos
Proteínas de Membrana , Perfil de Ribossomos
6.
Int J Mol Sci ; 23(23)2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36499346

RESUMO

Protein secretion plays a central role in modulating interactions of the human pathogen Listeria monocytogenes with its environment. Recently, secretion of RNA has emerged as an important strategy used by the pathogen to manipulate the host cell response to its advantage. In general, the Sec-dependent translocation pathway is a major route for protein secretion in L. monocytogenes, but mechanistic insights into the secretion of RNA by these pathways are lacking. Apart from the classical SecA1 secretion pathway, L. monocytogenes also encodes for a SecA paralogue (SecA2) which targets the export of a specific subset of proteins, some of which are involved in virulence. Here, we demonstrated that SecA2 co-sediments with translating ribosomes and provided evidence that it associates with a subset of secreted small non-coding RNAs (sRNAs) that induce high levels of IFN-ß response in host cells. We found that enolase, which is translocated by a SecA2-dependent mechanism, binds to several sRNAs, suggesting a pathway by which sRNAs are targeted to the supernatant of L. monocytogenes.


Assuntos
Listeria monocytogenes , Proteínas de Membrana Transportadoras , Humanos , Proteínas de Membrana Transportadoras/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Proteínas de Bactérias/metabolismo , RNA/metabolismo
7.
Cell Rep ; 41(9): 111734, 2022 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-36450251

RESUMO

The chaperone heat shock protein 90 (Hsp90) is well known to undergo important conformational changes, which depend on nucleotide and substrate interactions. Conversely, how the conformations of its unstable and disordered substrates are affected by Hsp90 is difficult to address experimentally yet is central to its function. Here, using optical tweezers, we find that Hsp90 promotes local contractions in unfolded chains that drive their global compaction down to dimensions of folded states. This compaction has a gradual nature while showing small steps, is stimulated by ATP, and performs mechanical work against counteracting forces that expand the chain dimensions. The Hsp90 interactions suppress the formation of larger-scale folded, misfolded, and aggregated structures. The observations support a model in which Hsp90 alters client conformations directly by promoting local intra-chain interactions while suppressing distant ones. We conjecture that chain compaction may be central to how Hsp90 protects unstable clients and cooperates with Hsp70.


Assuntos
Proteínas de Choque Térmico HSP70 , Proteínas de Choque Térmico HSP90 , Humanos , Nucleotídeos
8.
Epilepsy Behav ; 134: 108857, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35907288

RESUMO

BACKGROUND: Anxiety disorders remain undiagnosed in routine clinical practice in up to two thirds of affected patients with epilepsy despite their significant impact on medical and psychosocial outcomes. The study objective was to translate and validate the German 8-item "brief Epilepsy Anxiety Survey Instrument" (brEASI) to facilitate effective screening for the presence of anxiety disorders in German-speaking patients. METHODS: After expert translation into German, the brEASI was completed by consecutive adult inpatients with epilepsy hospitalized for seizures at an academic reference epilepsy center. Patients also completed the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), the Generalized Anxiety Disorder scale (GAD-7) for external validity, and underwent a standardized interview (Mini-DIPS-OA) as a gold standard to determine the presence of an ICD-10 anxiety disorder (generalized anxiety disorder (GAD), panic disorder, agoraphobia, and social phobia). Receiver operating characteristics (ROC) were calculated to determine the diagnostic accuracy of the brEASI, including the associated area under the curve (AUC) statistics to determine the potential of the brEASI to identify ICD-10 anxiety disorders diagnosed by interview. For comparative purposes, these analyses were also conducted for the GAD-7. RESULTS: Of 80 recruited adult inpatients with epilepsy, 18 (23 %) were found to have a current anxiety disorder through standardized interview. In this study, both brEASI and GAD-7 showed a better diagnostic performance at a cutoff of >5 than at the previously reported cutoff values of >6 and >9, respectively. The AUC of the German brEASI was outstanding (AUC = 0.90, 95 % confidence interval (CI) = 0.82-0.96) for detecting all anxiety disorders and excellent for detecting non-GAD disorders (AUC = 0.85, CI = 0.76-0.92) at a cutoff of >5. At this optimal cutoff of >5 the brEASI demonstrated better sensitivity and specificity (89 % and 84 %) for identifying anxiety disorders than the GAD-7 (83 % and 74 %). The final German version of the brEASI is free to download at https://www.v-neuro.de/veroeffentlichungen/. CONCLUSION: The German version of the brEASI represents a valid and reliable epilepsy-specific anxiety screening instrument. A positive screening result should be followed by further diagnostic procedures. Appropriate therapeutic steps should be initiated if the presence of an anxiety disorder or other psychiatric disorders is confirmed.


Assuntos
Transtornos de Ansiedade , Epilepsia , Adulto , Ansiedade , Humanos , Escalas de Graduação Psiquiátrica , Psicometria , Curva ROC , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
Sci Adv ; 8(9): eabl6293, 2022 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-35245117

RESUMO

The collapse of polypeptides is thought important to protein folding, aggregation, intrinsic disorder, and phase separation. However, whether polypeptide collapse is modulated in cells to control protein states is unclear. Here, using integrated protein manipulation and imaging, we show that the chaperonin GroEL-ES can accelerate the folding of proteins by strengthening their collapse. GroEL induces contractile forces in substrate chains, which draws them into the cavity and triggers a general compaction and discrete folding transitions, even for slow-folding proteins. This collapse enhancement is strongest in the nucleotide-bound states of GroEL and is aided by GroES binding to the cavity rim and by the amphiphilic C-terminal tails at the cavity bottom. Collapse modulation is distinct from other proposed GroEL-ES folding acceleration mechanisms, including steric confinement and misfold unfolding. Given the prevalence of collapse throughout the proteome, we conjecture that collapse modulation is more generally relevant within the protein quality control machinery.

10.
Epilepsy Behav ; 128: 108570, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35093831

RESUMO

OBJECTIVE: To investigate the opinions and attitudes of neurologists on the counseling about sudden unexpected death in epilepsy (SUDEP) worldwide. METHODS: Practicing neurologists from around the world were invited to participate in an online survey. On February 18th, 2021, we emailed an invitation including a questionnaire (using Google-forms) to the lead neurologists from 50 countries. The survey anonymously collected the demographic data of the participants and answers to the questions about their opinions and attitudes toward counseling about SUDEP. RESULTS: In total, 1123 neurologists from 27 countries participated; 41.5% of the respondents reported they discuss the risk of SUDEP with patients and their care-givers only rarely. Specific subgroups of patients who should especially be told about this condition were considered to be those with poor antiseizure medication (ASM) adherence, frequent tonic-clonic seizures, or with drug-resistant epilepsy. The propensity to tell all patients with epilepsy (PWE) about SUDEP was higher among those with epilepsy fellowship. Having an epilepsy fellowship and working in an academic setting were factors associated with a comfortable discussion about SUDEP. There were significant differences between the world regions. CONCLUSION: Neurologists often do not discuss SUDEP with patients and their care-givers. While the results of this study may not be representative of practitioners in each country, it seems that there is a severe dissociation between the clinical significance of SUDEP and the amount of attention that is devoted to this matter in daily practice by many neurologists around the world.


Assuntos
Morte Súbita Inesperada na Epilepsia , Atitude , Aconselhamento , Morte Súbita/epidemiologia , Morte Súbita/etiologia , Humanos , Neurologistas , Fatores de Risco , Inquéritos e Questionários
11.
Proc Natl Acad Sci U S A ; 118(51)2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34911752

RESUMO

The presence of a single cluster of nonoptimal codons was found to decrease a transcript's half-life through the interaction of the ribosome-associated quality control machinery with stalled ribosomes in Saccharomyces cerevisiae The impact of multiple nonoptimal codon clusters on a transcript's half-life, however, is unknown. Using a kinetic model, we predict that inserting a second nonoptimal cluster near the 5' end can lead to synergistic effects that increase a messenger RNA's (mRNA's) half-life in S. cerevisiae Specifically, the 5' end cluster suppresses the formation of ribosome queues, reducing the interaction of ribosome-associated quality control factors with stalled ribosomes. We experimentally validate this prediction by introducing two nonoptimal clusters into three different genes and find that their mRNA half-life increases up to fourfold. The model also predicts that in the presence of two clusters, the cluster closest to the 5' end is the primary determinant of mRNA half-life. These results suggest the "translational ramp," in which nonoptimal codons are located near the start codon and increase translational efficiency, may have the additional biological benefit of allowing downstream slow-codon clusters to be present without decreasing mRNA half-life. These results indicate that codon usage bias plays a more nuanced role in controlling cellular protein levels than previously thought.


Assuntos
Biossíntese de Proteínas , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas Fúngicas/biossíntese , Meia-Vida , Modelos Genéticos
12.
Front Mol Biosci ; 8: 689755, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34113653

RESUMO

Growing cells invest a significant part of their biosynthetic capacity into the production of proteins. To become functional, newly-synthesized proteins must be N-terminally processed, folded and often translocated to other cellular compartments. A general strategy is to integrate these protein maturation processes with translation, by cotranslationally engaging processing enzymes, chaperones and targeting factors with the nascent polypeptide. Precise coordination of all factors involved is critical for the efficiency and accuracy of protein synthesis and cellular homeostasis. This review provides an overview of the current knowledge on cotranslational protein maturation, with a focus on the production of cytosolic proteins in bacteria. We describe the role of the ribosome and the chaperone network in protein folding and how the dynamic interplay of all cotranslationally acting factors guides the sequence of cotranslational events. Finally, we discuss recent data demonstrating the coupling of protein synthesis with the assembly of protein complexes and end with a brief discussion of outstanding questions and emerging concepts in the field of cotranslational protein maturation.

13.
Seizure ; 91: 513-514, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34030934
14.
Geburtshilfe Frauenheilkd ; 81(2): 152-182, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33623171

RESUMO

Aims This is an official interdisciplinary guideline published and coordinated by the German Society for Gynecology and Obstetrics (DGGG), the Austrian Society for Gynecology and Obstetrics (OEGGG) and the Swiss Society for Gynecology and Obstetrics (SGGG). The guideline was developed for use in German-speaking regions and is backed by numerous professional societies and organizations. The aim of this guideline is to provide an evidence- and consensus-based overview of the diagnostic approach and the management of hormonal contraception based on a systematic evaluation of the relevant literature. Methods To compile this S3-guideline, a systematic search for evidence was carried out in PubMed and the Cochrane Library to adapt existing guidelines and identify relevant reviews and meta-analyses. A structured evaluation of the evidence was subsequently carried out on behalf of the Guidelines Commission of the DGGG, and a structured consensus was achieved based on consensus conferences attended by representative members from the different specialist societies and professions. Recommendations Evidence-based recommendations about the advice given to women requesting contraception were compiled. The guideline particularly focuses on prescribing contraceptives which are appropriate to women's individual needs, take account of her personal circumstances, and have few or no side effects.

15.
Cell Rep ; 34(5): 108711, 2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33535049

RESUMO

N-terminal (Nt) acetylation is a highly prevalent co-translational protein modification in eukaryotes, catalyzed by at least five Nt acetyltransferases (Nats) with differing specificities. Nt acetylation has been implicated in protein quality control, but its broad biological significance remains elusive. We investigate the roles of the two major Nats of S. cerevisiae, NatA and NatB, by performing transcriptome, translatome, and proteome profiling of natAΔ and natBΔ mutants. Our results reveal a range of NatA- and NatB-specific phenotypes. NatA is implicated in systemic adaptation control, because natAΔ mutants display altered expression of transposons, sub-telomeric genes, pheromone response genes, and nuclear genes encoding mitochondrial ribosomal proteins. NatB predominantly affects protein folding, because natBΔ mutants, to a greater extent than natA mutants, accumulate protein aggregates, induce stress responses, and display reduced fitness in the absence of the ribosome-associated chaperone Ssb. These phenotypic differences indicate that controlling Nat activities may serve to elicit distinct cellular responses.


Assuntos
Acetiltransferases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Acetilação
16.
Science ; 371(6524): 57-64, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33384371

RESUMO

Accurate assembly of newly synthesized proteins into functional oligomers is crucial for cell activity. In this study, we investigated whether direct interaction of two nascent proteins, emerging from nearby ribosomes (co-co assembly), constitutes a general mechanism for oligomer formation. We used proteome-wide screening to detect nascent chain-connected ribosome pairs and identified hundreds of homomer subunits that co-co assemble in human cells. Interactions are mediated by five major domain classes, among which N-terminal coiled coils are the most prevalent. We were able to reconstitute co-co assembly of nuclear lamin in Escherichia coli, demonstrating that dimer formation is independent of dedicated assembly machineries. Co-co assembly may thus represent an efficient way to limit protein aggregation risks posed by diffusion-driven assembly routes and ensure isoform-specific homomer formation.


Assuntos
Biossíntese de Proteínas , Multimerização Proteica , Ribossomos/metabolismo , Escherichia coli , Células HEK293 , Humanos , Laminas/química , Laminas/metabolismo , Domínios Proteicos , Proteoma
17.
Mol Cell ; 81(2): 304-322.e16, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33357414

RESUMO

Protein synthesis must be finely tuned in the developing nervous system as the final essential step of gene expression. This study investigates the architecture of ribosomes from the neocortex during neurogenesis, revealing Ebp1 as a high-occupancy 60S peptide tunnel exit (TE) factor during protein synthesis at near-atomic resolution by cryoelectron microscopy (cryo-EM). Ribosome profiling demonstrated Ebp1-60S binding is highest during start codon initiation and N-terminal peptide elongation, regulating ribosome occupancy of these codons. Membrane-targeting domains emerging from the 60S tunnel, which recruit SRP/Sec61 to the shared binding site, displace Ebp1. Ebp1 is particularly abundant in the early-born neural stem cell (NSC) lineage and regulates neuronal morphology. Ebp1 especially impacts the synthesis of membrane-targeted cell adhesion molecules (CAMs), measured by pulsed stable isotope labeling by amino acids in cell culture (pSILAC)/bioorthogonal noncanonical amino acid tagging (BONCAT) mass spectrometry (MS). Therefore, Ebp1 is a central component of protein synthesis, and the ribosome TE is a focal point of gene expression control in the molecular specification of neuronal morphology during development.


Assuntos
Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica no Desenvolvimento , Neocórtex/metabolismo , Neurônios/metabolismo , Biossíntese de Proteínas , Proteostase/genética , Proteínas de Ligação a RNA/genética , Subunidades Ribossômicas Maiores de Eucariotos/genética , Animais , Animais Recém-Nascidos , Sítios de Ligação , Moléculas de Adesão Celular Neuronais/química , Moléculas de Adesão Celular Neuronais/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Linhagem Celular Tumoral , Microscopia Crioeletrônica , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Embrião de Mamíferos , Feminino , Masculino , Camundongos , Neocórtex/citologia , Neocórtex/crescimento & desenvolvimento , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese/genética , Neurônios/citologia , Cultura Primária de Células , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Subunidades Ribossômicas Maiores de Eucariotos/metabolismo , Subunidades Ribossômicas Maiores de Eucariotos/ultraestrutura , Partícula de Reconhecimento de Sinal/química , Partícula de Reconhecimento de Sinal/genética , Partícula de Reconhecimento de Sinal/metabolismo
18.
J Mol Biol ; 432(24): 166696, 2020 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-33152326

RESUMO

Variation in translation-elongation kinetics along a transcript's coding sequence plays an important role in the maintenance of cellular protein homeostasis by regulating co-translational protein folding, localization, and maturation. Translation-elongation speed is influenced by molecular factors within mRNA and protein sequences. For example, the presence of proline in the ribosome's P- or A-site slows down translation, but the effect of other pairs of amino acids, in the context of all 400 possible pairs, has not been characterized. Here, we study Saccharomyces cerevisiae using a combination of bioinformatics, mutational experiments, and evolutionary analyses, and show that many different pairs of amino acids and their associated tRNA molecules predictably and causally encode translation rate information when these pairs are present in the A- and P-sites of the ribosome independent of other factors known to influence translation speed including mRNA structure, wobble base pairing, tripeptide motifs, positively charged upstream nascent chain residues, and cognate tRNA concentration. The fast-translating pairs of amino acids that we identify are enriched four-fold relative to the slow-translating pairs across Saccharomyces cerevisiae's proteome, while the slow-translating pairs are enriched downstream of domain boundaries. Thus, the chemical identity of amino acid pairs contributes to variability in translation rates, elongation kinetics are causally encoded in the primary structure of proteins, and signatures of evolutionary selection indicate their potential role in co-translational processes.


Assuntos
Aminoácidos/genética , Elongação Traducional da Cadeia Peptídica/genética , Biossíntese de Proteínas , RNA de Transferência/genética , Ribossomos/genética , Biologia Computacional , Cinética , Mutação/genética , Dobramento de Proteína , Proteoma/genética , RNA Mensageiro/genética , Saccharomyces cerevisiae/genética
19.
Nat Commun ; 11(1): 4676, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938922

RESUMO

Translation efficiency varies considerably between different mRNAs, thereby impacting protein expression. Translation of the stress response master-regulator ATF4 increases upon stress, but the molecular mechanisms are not well understood. We discover here that translation factors DENR, MCTS1 and eIF2D are required to induce ATF4 translation upon stress by promoting translation reinitiation in the ATF4 5'UTR. We find DENR and MCTS1 are only needed for reinitiation after upstream Open Reading Frames (uORFs) containing certain penultimate codons, perhaps because DENR•MCTS1 are needed to evict only certain tRNAs from post-termination 40S ribosomes. This provides a model for how DENR and MCTS1 promote translation reinitiation. Cancer cells, which are exposed to many stresses, require ATF4 for survival and proliferation. We find a strong correlation between DENR•MCTS1 expression and ATF4 activity across cancers. Furthermore, additional oncogenes including a-Raf, c-Raf and Cdk4 have long uORFs and are translated in a DENR•MCTS1 dependent manner.


Assuntos
Fator 4 Ativador da Transcrição/genética , Fatores de Iniciação em Eucariotos/metabolismo , Biossíntese de Proteínas , Ribossomos/metabolismo , Regiões 5' não Traduzidas , Fator 4 Ativador da Transcrição/metabolismo , Proteínas de Ciclo Celular/genética , Códon , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Fatores de Iniciação em Eucariotos/genética , Regulação da Expressão Gênica , Células HeLa , Humanos , Neoplasias/genética , Proteínas Oncogênicas/genética , Oncogenes , Fases de Leitura Aberta , RNA Mensageiro , RNA de Transferência/genética , RNA de Transferência/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/genética , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Ribossomos/genética
20.
Epilepsy Behav ; 111: 107191, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32759059

RESUMO

Among the many literary works of all styles and types referring to epilepsy, fantastic literature forms a distinct and interesting subgroup. The article draws attention to two such works belonging to early 20th century German avant-garde where epilepsy is a key feature. Of the authors, Austrian Alfred Kubin (1877-1959) was a renowned artist and illustrator whose only published (and illustrated) novel "The Other Side" (1909) can be understood as the narrative of a complex epileptic experience, perhaps a dreamy state. Of the other author, Hermann Weyl (1893-1960), very little is known. He was a Jewish neuropsychiatrist who emigrated from Nazist Germany to Argentina in 1933. His only published literary work, the novella "The Epileptic" (1927), displays high literary ambitions. The topic epilepsy provided for him the desired access to the fantastic realm, and his professionality enabled him to address with great expertise aspects as diverse as postictal psychosis and social stigmatization. Both works are, thus, valuable contributions to the tradition of epilepsy in fantastic literature. A brief review of the latter includes Edgar Allan Poe, Victor Hugo, Charles Dickens, Gustav Meyrink, Mervin Peake, Russell Hoban, Eraldo Baldini, Haruki Murakami, Adam Fawer, and Christoph Ransmayr.


Assuntos
Epilepsia/história , Obras de Ficção como Assunto , Psiquiatria/história , Áustria/epidemiologia , Confusão , Epilepsia/epidemiologia , Alemanha/epidemiologia , História do Século XIX , História do Século XX , Humanos , Masculino
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