scholarly journals Release, rescue and recycling: termination of translation in mammalian mitochondria

2021 ◽  
Author(s):  
Eva Kummer ◽  
Katharina Noel Schubert ◽  
Tanja Schönhut ◽  
Alain Scaiola ◽  
Nenad Ban
Keyword(s):  
Screening Tool ◽  
Translation Termination ◽  
Elongation Factor ◽  
Translation System ◽  
Ribosome Recycling Factor ◽  
Mitochondrial Translation ◽  
Translation Process ◽  
Mammalian Mitochondria ◽  
Mitochondrial Ribosome ◽  
Nascent Chain

SummaryThe mitochondrial translation system originates from a bacterial ancestor but has substantially diverged in the course of evolution. Here, we use single particle cryo-EM as a screening tool to identify mitochondrial translation termination mechanisms and to describe them in molecular detail. We show how mitochondria release factor 1a releases the nascent chain from the ribosome when it encounters the canonical stop codons UAA and UAG. Furthermore, we define how the peptidyl-tRNA hydrolase ICT1 acts as a rescue factor on mitoribosomes that have stalled on truncated messages to recover them for protein synthesis. Finally, we present near-atomic models detailing the process of mitochondrial ribosome recycling, to explain how a dedicated elongation factor, mtEFG2, has specialized for cooperation with the mitochondrial ribosome recycling factor to dissociate the mitoribosomal subunits at the end of the translation process. (134 words)

scholarly journals Reconstitution of mammalian mitochondrial translation system capable of correct initiation and long polypeptide synthesis from leaderless mRNA

2020 ◽  
Author(s):  
Muhoon Lee ◽  
Noriko Matsunaga ◽  
Shiori Akabane ◽  
Ippei Yasuda ◽  
Takuya Ueda ◽  
...  
Keyword(s):  
Liver Mitochondria ◽  
In Vitro Translation ◽  
Translation System ◽  
Mitochondrial Translation ◽  
Ribosome Stalling ◽  
Leaderless Mrna ◽  
Mammalian Mitochondria ◽  
Mitochondrial Ribosome ◽  
Nascent Chain

Abstract Mammalian mitochondria have their own dedicated protein synthesis system, which produces 13 essential subunits of the oxidative phosphorylation complexes. We have reconstituted an in vitro translation system from mammalian mitochondria, utilizing purified recombinant mitochondrial translation factors, 55S ribosomes from pig liver mitochondria, and a tRNA mixture from either Escherichia coli or yeast. The system is capable of translating leaderless mRNAs encoding model proteins (DHFR and nanoLuciferase) or some mtDNA-encoded proteins. We show that a leaderless mRNA, encoding nanoLuciferase, is faithfully initiated without the need for any auxiliary factors other than IF-2mt and IF-3mt. We found that the ribosome-dependent GTPase activities of both the translocase EF-G1mt and the recycling factor EF-G2mt are insensitive to fusidic acid (FA), the translation inhibitor that targets bacterial EF-G homologs, and consequently the system is resistant to FA. Moreover, we demonstrate that a polyproline sequence in the protein causes 55S mitochondrial ribosome stalling, yielding ribosome nascent chain complexes. Analyses of the effects of the Mg concentration on the polyproline-mediated ribosome stalling suggested the unique regulation of peptide elongation by the mitoribosome. This system will be useful for analyzing the mechanism of translation initiation, and the interactions between the nascent peptide chain and the mitochondrial ribosome.

scholarly journals Chronic ethanol feeding causes depression of mitochondrial elongation factor Tu in the rat liver: implications for the mitochondrial ribosome

2011 ◽  
Vol 300 (5) ◽  
pp. G815-G822 ◽  
Author(s):  
Brian Weiser ◽  
Gregory Gonye ◽  
Peter Sykora ◽  
Sara Crumm ◽  
Alan Cahill
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Elongation Factor ◽  
Chronic Ethanol ◽  
Male Rats ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation ◽  
Hepatic Energy Metabolism ◽  
Mitochondrial Ribosome ◽  
Ethanol Feeding

Chronic ethanol feeding is known to negatively impact hepatic energy metabolism. Previous studies have indicated that the underlying lesion responsible for this may lie at the level of the mitoribosome. The aim of this study was to characterize the structure of the hepatic mitoribosome in alcoholic male rats and their isocalorically paired controls. Our experiments revealed that chronic ethanol feeding resulted in a significant depletion of both structural (death-associated protein 3) and functional [elongation factor thermo unstable (EF-Tu)] mitoribosomal proteins. In addition, significant increases were found in nucleotide elongation factor thermo stable (EF-Ts) and structural mitochondrial ribosomal protein L12 (MRPL12). The increase in MRPL12 was found to correlate with an increase in the levels of the 39S large mitoribosomal subunit. These changes were accompanied by decreased levels of nuclear- and mitochondrially encoded respiratory subunits, decreased amounts of intact respiratory complexes, decreased hepatic ATP levels, and depressed mitochondrial translation. Mathematical modeling of ethanol-mediated changes in EF-Tu and EF-Ts using prederived kinetic data predicted that the ethanol-mediated decrease in EF-Tu levels could completely account for the impaired mitochondrial protein synthesis. In conclusion, chronic ethanol feeding results in a depletion of mitochondrial EF-Tu levels within the liver that is mathematically predicted to be responsible for the impaired mitochondrial protein synthesis seen in alcoholic animals.

scholarly journals Structures of the human mitochondrial ribosome recycling complexes reveal distinct mechanisms of recycling and antibiotic resistance

2020 ◽  
Author(s):  
Ravi Kiran Koripella ◽  
Ayush Deep ◽  
Ekansh K. Agrawal ◽  
Pooja Keshavan ◽  
Nilesh K. Banavali ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Conformational Changes ◽  
Messenger Rna ◽  
Elongation Factor ◽  
Ribosome Recycling Factor ◽  
Ribosomal Subunits ◽  
Sequence Of Events ◽  
Mitochondrial Ribosome ◽  
Mitochondrial Elongation

AbstractRibosomes are recycled for a new round of translation initiation by dissociation of ribosomal subunits, messenger RNA and transfer RNA from their translational post-termination complex. Mitochondrial ribosome recycling factor (RRFmt) and a recycling-specific homolog of elongation factor G (EF-G2mt) are two proteins with mitochondria-specific additional sequences that catalyze the recycling step in human mitochondria. We have determined high-resolution cryo-EM structures of the human 55S mitochondrial ribosome (mitoribosome) in complex with RRFmt, and the mitoribosomal large 39S subunit in complex with both RRFmt and EF-G2mt. In addition, we have captured the structure of a short-lived intermediate state of the 55S•RRFmt•EF-G2mt complex. These structures clarify the role of a mitochondria-specific segment of RRFmt in mitoribosome recycling, identify the structural distinctions between the two isoforms of EF-Gmt that confer their functional specificity, capture recycling-specific conformational changes in the L7/L12 stalk-base region, and suggest a distinct mechanistic sequence of events in mitoribosome recycling. Furthermore, biochemical and structural assessments of the sensitivity of EF-G2mt to the antibiotic fusidic acid reveals that the molecular mechanism of antibiotic resistance for EF-G2mt is markedly different from that exhibited by mitochondrial elongation factor EF-G1mt, suggesting that these two homologous mitochondrial proteins have evolved diversely to negate the effect of a bacterial antibiotics.

scholarly journals A protein extension to shorten RNA: elongated elongation factor-Tu recognizes the D-arm of T-armless tRNAs in nematode mitochondria

2006 ◽  
Vol 399 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Masayuki Sakurai ◽  
Yoh-ichi Watanabe ◽  
Kimitsuna Watanabe ◽  
Takashi Ohtsuki
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Elongation Factor ◽  
Binding Activity ◽  
Translation System ◽  
Elongation Factor Tu ◽  
Mitochondrial Translation ◽  
Recognition Mechanism ◽  
C Elegans ◽  
C Terminus

Nematode mitochondria possess extremely truncated tRNAs. Of 22 tRNAs, 20 lack the entire T-arm. The T-arm is necessary for the binding of canonical tRNAs and EF (elongation factor)-Tu (thermo-unstable). The nematode mitochondrial translation system employs two different EF-Tu factors named EF-Tu1 and EF-Tu2. Our previous study showed that nematode Caenorhabditis elegans EF-Tu1 binds specifically to T-armless tRNA. C. elegans EF-Tu1 has a 57-amino acid C-terminal extension that is absent from canonical EF-Tu, and the T-arm-binding residues of canonical EF-Tu are not conserved. In this study, the recognition mechanism of T-armless tRNA by EF-Tu1 was investigated. Both modification interference assays and primer extension analysis of cross-linked ternary complexes revealed that EF-Tu1 interacts not only with the tRNA acceptor stem but also with the D-arm. This is the first example of an EF-Tu recognizing the D-arm of a tRNA. The binding activity of EF-Tu1 was impaired by deletion of only 14 residues from the C-terminus, indicating that the C-terminus of EF-Tu1 is required for its binding to T-armless tRNA. These results suggest that C. elegans EF-Tu1 recognizes the D-arm instead of the T-arm by a mechanism involving its C-terminal region. This study sheds light on the co-evolution of RNA and RNA-binding proteins in nematode mitochondria.

scholarly journals Proteomic profiling of the mitochondrial ribosome identifies Atp25 as a composite mitochondrial precursor protein

2016 ◽  
Vol 27 (20) ◽  
pp. 3031-3039 ◽  
Author(s):  
Michael W. Woellhaf ◽  
Frederik Sommer ◽  
Michael Schroda ◽  
Johannes M. Herrmann
Keyword(s):  
Precursor Protein ◽  
Ribosomal Biogenesis ◽  
Proteomic Profiling ◽  
Mitochondrial Translation ◽  
Bacterial Ribosome ◽  
Mitochondrial Ribosome ◽  
Translation Apparatus ◽  
The Matrix ◽  
Processing Peptidase ◽  
And Function

Whereas the structure and function of cytosolic ribosomes are well characterized, we only have a limited understanding of the mitochondrial translation apparatus. Using SILAC-based proteomic profiling, we identified 13 proteins that cofractionated with the mitochondrial ribosome, most of which play a role in translation or ribosomal biogenesis. One of these proteins is a homologue of the bacterial ribosome-silencing factor (Rsf). This protein is generated from the composite precursor protein Atp25 upon internal cleavage by the matrix processing peptidase MPP, and in this respect, it differs from all other characterized mitochondrial proteins of baker’s yeast. We observed that cytosolic expression of Rsf, but not of noncleaved Atp25 protein, is toxic. Our results suggest that eukaryotic cells face the challenge of avoiding negative interference from the biogenesis of their two distinct translation machineries.

Research on Machine Translation Technology in English Translation Process

2014 ◽  
Vol 687-691 ◽  
pp. 1210-1213
Author(s):  
Ke Tian
Keyword(s):  
Machine Translation ◽  
English Translation ◽  
Development Process ◽  
Translation System ◽  
Translation Process ◽  
Sentence Meaning ◽  
Cultural Exchanges ◽  
Response Measures ◽  
World Economic ◽  
Translation Machine

Translation plays an important role in the world economic and cultural exchanges. Translation is divided into machine translation and human translation, which is complement each other in promoting world economic and social development process. In this paper, Collaborative Translation gets much attention, along with the growth of collaborative translation, English translation technology also towards a new milestone, the characteristics of collaborative translation process and scientific literature are briefly introduced, and collaborative translation technology English Translation applications made a brief explanation. From the perspective of the development of machine translation, comparative analysis of the characteristics of human translation machine translation strengths and weaknesses, and we make relevant response measures and selection criteria translation approach. The specific translation system is analyzed from the perspective of textual and the Collaborative Translation shortcomings, as well as interpretation of collaborative translation features, functions and its impact on the meaning and sentence meaning.

scholarly journals Mitochondrial Retrograde Signaling Contributes to Metabolic Differentiation in Yeast Colonies

2021 ◽  
Vol 22 (11) ◽  
pp. 5597
Author(s):  
Vítězslav Plocek ◽  
Kristýna Fadrhonc ◽  
Jana Maršíková ◽  
Libuše Váchová ◽  
Alexandra Pokorná ◽  
...  
Keyword(s):  
Cell Types ◽  
Colony Development ◽  
Mitochondrial Activity ◽  
Mitochondrial Translation ◽  
Metabolic Intermediates ◽  
Nutritional Conditions ◽  
Mitochondrial Ribosome ◽  
Development And Differentiation ◽  
Cell Subpopulations ◽  
Different Cell Types

During development of yeast colonies, various cell subpopulations form, which differ in their properties and specifically localize within the structure. Three branches of mitochondrial retrograde (RTG) signaling play a role in colony development and differentiation, each of them activating the production of specific markers in different cell types. Here, aiming to identify proteins and processes controlled by the RTG pathway, we analyzed proteomes of individual cell subpopulations from colonies of strains, mutated in genes of the RTG pathway. Resulting data, along with microscopic analyses revealed that the RTG pathway predominantly regulates processes in U cells, long-lived cells with unique properties, which are localized in upper colony regions. Rtg proteins therein activate processes leading to amino acid biosynthesis, including transport of metabolic intermediates between compartments, but also repress expression of mitochondrial ribosome components, thus possibly contributing to reduced mitochondrial translation in U cells. The results reveal the RTG pathway’s role in activating metabolic processes, important in U cell adaptation to altered nutritional conditions. They also point to the important role of Rtg regulators in repressing mitochondrial activity in U cells.

scholarly journals Coupling of mitochondrial translation with the formation of respiratory complexes in yeast mitochondria.

2000 ◽  
Vol 47 (4) ◽  
pp. 973-991 ◽  
Author(s):  
A Chacińska ◽  
M Boguta
Keyword(s):  
Mitochondrial Dna ◽  
Genomic Sequence ◽  
Mitochondrial Translation ◽  
Translation Process ◽  
Cellular Compartment ◽  
Respiratory Complexes ◽  
Mitochondrial Ribosomes ◽  
Eukaryotic Organisms ◽  
Export System

In contrast to most other eukaryotic organisms, yeast can survive without respiration. This ability has been exploited to investigate nuclear genes required for expression of mitochondrial DNA. Availability of complete Saccharomyces cerevisiae genomic sequence has provided additional help in detailed molecular analysis. Seven of the eight major products encoded by mitochondrial DNA are hydrophobic subunits of respiratory complexes in the inner membrane. Localization of the translation process in the same cellular compartment ensures synthesis of mitochondrially encoded proteins near sites of their assembly into multimeric respiratory complexes. Association of mitochondrial ribosomes with the membrane is mediated by mRNA-specific translational activators, that are involved in the recognition of initiation codon. The newly synthesized mitochondrial proteins are transferred to membrane by a specific export system. This review discusses the role of membrane-localized factors responsible for quality control and turnover of mitochondrially synthesized subunits as well as for assembly of respiratory complexes.

scholarly journals Elongation Factor G Is a Critical Target during Oxidative Damage to the Translation System ofEscherichia coli

2012 ◽  
Vol 287 (34) ◽  
pp. 28697-28704 ◽  
Author(s):  
Takanori Nagano ◽  
Kouji Kojima ◽  
Toru Hisabori ◽  
Hidenori Hayashi ◽  
Eugene Hayato Morita ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Elongation Factor ◽  
Ofescherichia Coli ◽  
Translation System ◽  
Elongation Factor G ◽  
Factor G

scholarly journals Dysregulated pathways for off-pump coronary artery bypass grafting

2017 ◽  
Vol 12 (1) ◽  
pp. 399-405
Author(s):  
Xu Li ◽  
Dao-Kang Xiang ◽  
Yi-Zhu Shu ◽  
Cheng-Hui Feng
Keyword(s):  
Coronary Artery ◽  
Coronary Artery Bypass Grafting ◽  
Coronary Artery Bypass ◽  
Translation Termination ◽  
Artery Bypass ◽  
Bypass Grafting ◽  
Mitochondrial Translation ◽  
Artery Bypass Grafting ◽  
Off Pump ◽  
Pump Coronary Artery Bypass

AbstractBackgroundThe objective of this paper was to identify dysregulated myocardial pathways with off-pump coronary artery bypass grafting (OPCABG) based on pathway interaction network (PIN).MethodologyTo achieve this goal, firstly, gene expression profiles, protein-protein interactions (PPIs) and pathway data were collected. Secondly, we constructed a PIN by integrating these data and Pearson correlation coefficient (PCC) algorithm. Next, for every pathway in the PIN, its activity was counted dependent on the principal component analysis (PCA) method to select the seed pathway. Ultimately, a minimum pathway set (MPS) was extracted from the PIN on the basis of the seed pathway and the area under the receiver operating characteristics curve (AUROC) index, and pathways in the MPS were denoted as dysregulated pathways.ResultsThe PIN had 1,189 nodes and 22,756 interactions, of which mitochondrial translation termination was the seed pathway. Starting with mitochondrial translation termination, a MPS (AUROC = 0.983) with 7 nodes and 26 edges was obtained. The 7 pathways were regarded as dysregulated myocardial pathways with OPCABG.ConclusionThe findings might provide potential biomarkers to diagnose early, serve as the evidence to perform the OPCABG and predict inflammatory response and myocardial reperfusion injury after OPCABG in the future.

Sign in / Sign up

Export Citation Format

Share Document