1
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Cherrak Y, Salazar MA, Näpflin N, Malfertheiner L, Herzog MKM, Schubert C, von Mering C, Hardt WD. Non-canonical start codons confer context-dependent advantages in carbohydrate utilization for commensal E. coli in the murine gut. Nat Microbiol 2024:10.1038/s41564-024-01775-x. [PMID: 39160293 DOI: 10.1038/s41564-024-01775-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 07/04/2024] [Indexed: 08/21/2024]
Abstract
Resource competition is a driver of gut microbiota composition. Bacteria can outcompete metabolically similar rivals through the limitation of shared growth-fuelling nutrients. The mechanisms underlying this remain unclear for bacteria with identical sets of metabolic genes. Here we analysed the lactose utilization operon in the murine commensal Escherichia coli 8178. Using in vitro and in vivo approaches, we showed that translation of the lactose utilization repressor gene lacI from its native non-canonical GTG start codon increases the basal expression of the lactose utilization cluster, enhancing adaptation to lactose consumption. Consequently, a strain carrying the wild type lacI GTG start codon outperformed the lacI ATG start codon mutant in the mouse intestine. This advantage was attenuated upon limiting host lactose intake through diet shift or altering the mutant frequency, emphasizing the context-dependent effect of a single nucleotide change on the bacterial fitness of a common member of the gut microbiota. Coupled with a genomic analysis highlighting the selection of non-ATG start codons in sugar utilization regulator genes across the Enterobacteriaceae family, our data exposed an unsuspected function of non-canonical start codons in metabolic competition.
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Affiliation(s)
- Yassine Cherrak
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
| | - Miguel Angel Salazar
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Nicolas Näpflin
- Department of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Lukas Malfertheiner
- Department of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Mathias K-M Herzog
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Christopher Schubert
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Christian von Mering
- Department of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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2
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Spealman P, de Santana C, De T, Gresham D. Multilevel gene expression changes in lineages containing adaptive copy number variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.20.563336. [PMID: 37961325 PMCID: PMC10634702 DOI: 10.1101/2023.10.20.563336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Copy-number variants (CNVs) are an important class of recurrent variants that mediate adaptive evolution. While CNVs can increase the relative fitness of the organism, they can also incur a cost. We previously evolved populations of Saccharomyces cerevisiae over hundreds of generations in glutamine-limited (Gln-) chemostats and observed the recurrent evolution of CNVs at the GAP1 locus. To understand the role that expression plays in adaptation, both in relation to the adaptation of the organism to the selective condition, and as a consequence of the CNV, we measured the transcriptome, translatome, and proteome of 4 strains of evolved yeast, each with a unique CNV, and their ancestor in Gln- conditions. We find CNV-amplified genes correlate with higher RNA abundance; however, this effect is reduced at the level of the proteome, consistent with post-transcriptional dosage compensation. By normalizing each level of expression by the abundance of the preceding step we were able to identify widespread divergence in the efficiency of each step in the gene in the efficiency of each step in gene expression. Genes with significantly different translational efficiency were enriched for potential regulatory mechanisms including either upstream open reading frames, RNA binding sites for SSD1, or both. Genes with lower protein expression efficiency were enriched for genes encoding proteins in protein complexes. Taken together, our study reveals widespread changes in gene expression at multiple regulatory levels in lineages containing adaptive CNVs highlighting the diverse ways in which adaptive evolution shapes gene expression.
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Affiliation(s)
- Pieter Spealman
- Center for Genomics and Systems Biology, Department of Biology, New York University
| | - Carolina de Santana
- Laboratório de Microbiologia Ambiental e Saúde Pública - Universidade Estadual de Feira de Santana (UEFS), Bahia
| | - Titir De
- Center for Genomics and Systems Biology, Department of Biology, New York University
| | - David Gresham
- Center for Genomics and Systems Biology, Department of Biology, New York University
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3
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Chloroplasts evolved an additional layer of translational regulation based on non-AUG start codons for proteins with different turnover rates. Sci Rep 2023; 13:896. [PMID: 36650197 PMCID: PMC9845219 DOI: 10.1038/s41598-022-27347-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 12/30/2022] [Indexed: 01/18/2023] Open
Abstract
Chloroplasts have evolved from photosynthetic cyanobacteria-like progenitors through endosymbiosis. The chloroplasts of present-day land plants have their own transcription and translation systems that show several similarities with prokaryotic organisms. A remarkable feature of the chloroplast translation system is the use of non-AUG start codons in the protein synthesis of certain genes that are evolutionarily conserved from Algae to angiosperms. However, the biological significance of such use of non-AUG codons is not fully understood. The present study was undertaken to unravel the significance of non-AUG start codons in vivo using the chloroplast genetic engineering approach. For this purpose, stable transplastomic tobacco plants expressing a reporter gene i.e. uidA (GUS) under four different start codons (AUG/UUG/GUG/CUG) were generated and β-glucuronidase (GUS) expression was compared. To investigate further the role of promoter sequences proximal to the start codon, uidA was expressed under two different chloroplast gene promoters psbA and psbC that use AUG and a non-AUG (GUG) start codons, respectively, and also showed significant differences in the DNA sequence surrounding the start codon. Further, to delineate the role of RNA editing that creates AUG start codon by editing non-AUG codons, if any, which is another important feature of the chloroplast transcription and translation system, transcripts were sequenced. In addition, a proteomic approach was used to identify the translation initiation site(s) of GUS and the N-terminal amino acid encoded when expressed under different non-AUG start codons. The results showed that chloroplasts use non-AUG start codons in combination with the translation initiation site as an additional layer of gene regulation to over-express proteins that are required at high levels due to their high rates of turnover.
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4
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Ram AK, Mallik M, Reddy RR, Suryawanshi AR, Alone PV. Altered proteome in translation initiation fidelity defective eIF5 G31R mutant causes oxidative stress and DNA damage. Sci Rep 2022; 12:5033. [PMID: 35322093 PMCID: PMC8943034 DOI: 10.1038/s41598-022-08857-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/07/2022] [Indexed: 12/15/2022] Open
Abstract
The recognition of the AUG start codon and selection of an open reading frame (ORF) is fundamental to protein biosynthesis. Defect in the fidelity of start codon selection adversely affect proteome and have a pleiotropic effect on cellular function. Using proteomic techniques, we identified differential protein abundance in the translation initiation fidelity defective eIF5G31R mutant that initiates translation using UUG codon in addition to the AUG start codon. Consistently, the eIF5G31R mutant altered proteome involved in protein catabolism, nucleotide biosynthesis, lipid biosynthesis, carbohydrate metabolism, oxidation–reduction pathway, autophagy and re-programs the cellular pathways. The utilization of the upstream UUG codons by the eIF5G31R mutation caused downregulation of uridylate kinase expression, sensitivity to hydroxyurea, and DNA damage. The eIF5G31R mutant cells showed lower glutathione levels, high ROS activity, and sensitivity to H2O2.
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Affiliation(s)
- Anup Kumar Ram
- School of Biological Sciences, National Institute of Science Education and Research Bhubaneswar, P.O Jatni, Khurda, 752050, India.,Homi Bhabha National Institute (HBNI), Anushakti Nagar, Mumbai, 400094, India
| | - Monalisha Mallik
- School of Biological Sciences, National Institute of Science Education and Research Bhubaneswar, P.O Jatni, Khurda, 752050, India.,Homi Bhabha National Institute (HBNI), Anushakti Nagar, Mumbai, 400094, India
| | - R Rajendra Reddy
- Clinical Proteomics, DBT-Institute of Life Sciences, Bhubaneswar, Odisha, 751023, India
| | | | - Pankaj V Alone
- School of Biological Sciences, National Institute of Science Education and Research Bhubaneswar, P.O Jatni, Khurda, 752050, India. .,Homi Bhabha National Institute (HBNI), Anushakti Nagar, Mumbai, 400094, India.
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5
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Jaquet V, Wallerich S, Voegeli S, Túrós D, Viloria EC, Becskei A. Determinants of the temperature adaptation of mRNA degradation. Nucleic Acids Res 2022; 50:1092-1110. [PMID: 35018460 PMCID: PMC8789057 DOI: 10.1093/nar/gkab1261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/04/2021] [Accepted: 12/09/2021] [Indexed: 12/26/2022] Open
Abstract
The rate of chemical reactions increases proportionally with temperature, but the interplay of biochemical reactions permits deviations from this relation and adaptation. The degradation of individual mRNAs in yeast increased to varying degrees with temperature. We examined how these variations are influenced by the translation and codon composition of mRNAs. We developed a method that revealed the existence of a neutral half-life above which mRNAs are stabilized by translation but below which they are destabilized. The proportion of these two mRNA subpopulations remained relatively constant under different conditions, even with slow cell growth due to nutrient limitation, but heat shock reduced the proportion of translationally stabilized mRNAs. At the same time, the degradation of these mRNAs was partially temperature-compensated through Upf1, the mediator of nonsense-mediated decay. Compensation was also promoted by some asparagine and serine codons, whereas tyrosine codons promote temperature sensitization. These codons play an important role in the degradation of mRNAs encoding key cell membrane and cell wall proteins, which promote cell integrity.
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Affiliation(s)
- Vincent Jaquet
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Sandrine Wallerich
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Sylvia Voegeli
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Demeter Túrós
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Eduardo C Viloria
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Attila Becskei
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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6
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Antika TR, Chrestella DJ, Ivanesthi IR, Rida G, Chen KY, Liu FG, Lee YC, Chen YW, Tseng YK, Wang CC. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2190-2200. [PMID: 35100402 PMCID: PMC8887476 DOI: 10.1093/nar/gkac026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/14/2021] [Accepted: 01/11/2022] [Indexed: 11/14/2022] Open
Abstract
Unlike many other aminoacyl-tRNA synthetases, alanyl-tRNA synthetase (AlaRS) retains a conserved prototype structure throughout biology. While Caenorhabditis elegans cytoplasmic AlaRS (CeAlaRSc) retains the prototype structure, its mitochondrial counterpart (CeAlaRSm) contains only a residual C-terminal domain (C-Ala). We demonstrated herein that the C-Ala domain from CeAlaRSc robustly binds both tRNA and DNA. It bound different tRNAs but preferred tRNAAla. Deletion of this domain from CeAlaRSc sharply reduced its aminoacylation activity, while fusion of this domain to CeAlaRSm selectively and distinctly enhanced its aminoacylation activity toward the elbow-containing (or L-shaped) tRNAAla. Phylogenetic analysis showed that CeAlaRSm once possessed the C-Ala domain but later lost most of it during evolution, perhaps in response to the deletion of the T-arm (part of the elbow) from its cognate tRNA. This study underscores the evolutionary gain of C-Ala for docking AlaRS to the L-shaped tRNAAla.
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Affiliation(s)
- Titi Rindi Antika
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Dea Jolie Chrestella
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Indira Rizqita Ivanesthi
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Gita Riswana Nawung Rida
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Kuan-Yu Chen
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Fu-Guo Liu
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Taipei Veterans General Hospital, Beitou District, Taipei 11217, Taiwan
| | - Yu-Wei Chen
- Department of Neurology, Landseed International Hospital, Pingzhen District, Taoyuan 32449, Taiwan
| | - Yi-Kuan Tseng
- Graduate Institute of Statistics, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Chien-Chia Wang
- To whom correspondence should be addressed. Tel: +886 3 426 0840; Fax: +886 3 422 8482;
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7
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Young DJ, Meydan S, Guydosh NR. 40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling. Nat Commun 2021; 12:2976. [PMID: 34016977 PMCID: PMC8137927 DOI: 10.1038/s41467-021-23223-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/14/2021] [Indexed: 12/21/2022] Open
Abstract
The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we used a 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.
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Affiliation(s)
- David J Young
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sezen Meydan
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Postdoctoral Research Associate Training Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Nicholas R Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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8
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uORF-seqr: A Machine Learning-Based Approach to the Identification of Upstream Open Reading Frames in Yeast. Methods Mol Biol 2021. [PMID: 33765283 DOI: 10.1007/978-1-0716-1150-0_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The identification of upstream open reading frames (uORFs) using ribosome profiling data is complicated by several factors such as the noise inherent to the procedure, the substantial increase in potential translation initiation sites (and false positives) when one includes non-canonical start codons, and the paucity of molecularly validated uORFs. Here we present uORF-seqr, a novel machine learning algorithm that uses ribosome profiling data, in conjunction with RNA-seq data, as well as transcript aware genome annotation files to identify statistically significant AUG and near-cognate codon uORFs.
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9
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Higdon AL, Brar GA. Rules are made to be broken: a "simple" model organism reveals the complexity of gene regulation. Curr Genet 2020; 67:49-56. [PMID: 33130938 DOI: 10.1007/s00294-020-01121-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 11/27/2022]
Abstract
Global methods for assaying translation have greatly improved our understanding of the protein-coding capacity of the genome. In particular, it is now possible to perform genome-wide and condition-specific identification of translation initiation sites through modified ribosome profiling methods that selectively capture initiating ribosomes. Here we discuss our recent study applying such an approach to meiotic and mitotic timepoints in the simple eukaryote, budding yeast, as an example of the surprising diversity of protein products-many of which are non-canonical-that can be revealed by such methods. We also highlight several key challenges in studying non-canonical protein isoforms that have precluded their prior systematic discovery. A growing body of work supports expanded use of empirical protein-coding region identification, which can help relieve some of the limitations and biases inherent to traditional genome annotation approaches. Our study also argues for the adoption of less static views of gene identity and a broader framework for considering the translational capacity of the genome.
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Affiliation(s)
- Andrea L Higdon
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Center for Computational Biology, University of California, Berkeley, CA, 94720, USA
| | - Gloria A Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA.
- Center for Computational Biology, University of California, Berkeley, CA, 94720, USA.
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10
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Garin S, Levi O, Cohen B, Golani-Armon A, Arava YS. Localization and RNA Binding of Mitochondrial Aminoacyl tRNA Synthetases. Genes (Basel) 2020; 11:genes11101185. [PMID: 33053729 PMCID: PMC7600831 DOI: 10.3390/genes11101185] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/05/2020] [Accepted: 10/08/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria contain a complete translation machinery that is used to translate its internally transcribed mRNAs. This machinery uses a distinct set of tRNAs that are charged with cognate amino acids inside the organelle. Interestingly, charging is executed by aminoacyl tRNA synthetases (aaRS) that are encoded by the nuclear genome, translated in the cytosol, and need to be imported into the mitochondria. Here, we review import mechanisms of these enzymes with emphasis on those that are localized to both mitochondria and cytosol. Furthermore, we describe RNA recognition features of these enzymes and their interaction with tRNA and non-tRNA molecules. The dual localization of mitochondria-destined aaRSs and their association with various RNA types impose diverse impacts on cellular physiology. Yet, the breadth and significance of these functions are not fully resolved. We highlight here possibilities for future explorations.
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11
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Akirtava C, McManus CJ. Control of translation by eukaryotic mRNA transcript leaders-Insights from high-throughput assays and computational modeling. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1623. [PMID: 32869519 DOI: 10.1002/wrna.1623] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/23/2020] [Accepted: 07/30/2020] [Indexed: 12/21/2022]
Abstract
Eukaryotic gene expression is tightly regulated during translation of mRNA to protein. Mis-regulation of translation can lead to aberrant proteins which accumulate in cancers and cause neurodegenerative diseases. Foundational studies on model genes established fundamental roles for mRNA 5' transcript leader (TL) sequences in controlling ribosome recruitment, scanning, and initiation. TL cis-regulatory elements and their corresponding trans-acting factors control cap-dependent initiation under unstressed conditions. Under stress, cap-dependent initiation is suppressed, and specific mRNA structures and sequences promote translation of stress-responsive transcripts to remodel the proteome. In this review, we summarize current knowledge of TL functions in translation initiation. We focus on insights from high-throughput analyses of ribosome occupancy, mRNA structure, RNA Binding Protein occupancy, and massively parallel reporter assays. These data-driven approaches, coupled with computational analyses and modeling, have paved the way for a comprehensive understanding of TL functions. Finally, we will discuss areas of future research on the roles of mRNA sequences and structures in translation. This article is categorized under: Translation > Translation Mechanisms RNA Evolution and Genomics > Computational Analyses of RNA RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Christina Akirtava
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Charles Joel McManus
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.,Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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12
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Eisenberg AR, Higdon AL, Hollerer I, Fields AP, Jungreis I, Diamond PD, Kellis M, Jovanovic M, Brar GA. Translation Initiation Site Profiling Reveals Widespread Synthesis of Non-AUG-Initiated Protein Isoforms in Yeast. Cell Syst 2020; 11:145-160.e5. [PMID: 32710835 PMCID: PMC7508262 DOI: 10.1016/j.cels.2020.06.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/18/2020] [Accepted: 06/24/2020] [Indexed: 12/27/2022]
Abstract
Genomic analyses in budding yeast have helped define the foundational principles of eukaryotic gene expression. However, in the absence of empirical methods for defining coding regions, these analyses have historically excluded specific classes of possible coding regions, such as those initiating at non-AUG start codons. Here, we applied an experimental approach to globally annotate translation initiation sites in yeast and identified 149 genes with alternative N-terminally extended protein isoforms initiating from near-cognate codons upstream of annotated AUG start codons. These isoforms are produced in concert with canonical isoforms and translated with high specificity, resulting from initiation at only a small subset of possible start codons. The non-AUG initiation driving their production is enriched during meiosis and induced by low eIF5A, which is seen in this context. These findings reveal widespread production of non-canonical protein isoforms and unexpected complexity to the rules by which even a simple eukaryotic genome is decoded.
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Affiliation(s)
- Amy R Eisenberg
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Andrea L Higdon
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Center for Computational Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ina Hollerer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Alexander P Fields
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Irwin Jungreis
- MIT Computer Science and Artificial Intelligence Laboratory, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Paige D Diamond
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Manolis Kellis
- MIT Computer Science and Artificial Intelligence Laboratory, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Marko Jovanovic
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Gloria A Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Center for Computational Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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13
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Bader G, Enkler L, Araiso Y, Hemmerle M, Binko K, Baranowska E, De Craene JO, Ruer-Laventie J, Pieters J, Tribouillard-Tanvier D, Senger B, di Rago JP, Friant S, Kucharczyk R, Becker HD. Assigning mitochondrial localization of dual localized proteins using a yeast Bi-Genomic Mitochondrial-Split-GFP. eLife 2020; 9:56649. [PMID: 32657755 PMCID: PMC7358010 DOI: 10.7554/elife.56649] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/11/2020] [Indexed: 12/31/2022] Open
Abstract
A single nuclear gene can be translated into a dual localized protein that distributes between the cytosol and mitochondria. Accumulating evidences show that mitoproteomes contain lots of these dual localized proteins termed echoforms. Unraveling the existence of mitochondrial echoforms using current GFP (Green Fluorescent Protein) fusion microscopy approaches is extremely difficult because the GFP signal of the cytosolic echoform will almost inevitably mask that of the mitochondrial echoform. We therefore engineered a yeast strain expressing a new type of Split-GFP that we termed Bi-Genomic Mitochondrial-Split-GFP (BiG Mito-Split-GFP). Because one moiety of the GFP is translated from the mitochondrial machinery while the other is fused to the nuclear-encoded protein of interest translated in the cytosol, the self-reassembly of this Bi-Genomic-encoded Split-GFP is confined to mitochondria. We could authenticate the mitochondrial importability of any protein or echoform from yeast, but also from other organisms such as the human Argonaute 2 mitochondrial echoform.
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Affiliation(s)
- Gaétan Bader
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Ludovic Enkler
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Yuhei Araiso
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Marine Hemmerle
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Krystyna Binko
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Emilia Baranowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Johan-Owen De Craene
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | | | - Jean Pieters
- Biozentrum, University of Basel, Basel, Switzerland
| | | | - Bruno Senger
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Jean-Paul di Rago
- Institut de Biochimie et Génétique Cellulaires, CNRS UMR5095, Université de Bordeaux, Bordeaux, France
| | - Sylvie Friant
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Hubert Dominique Becker
- Université de Strasbourg, CNRS UMR7156, Génétique Moléculaire, Génomique, Microbiologie, Strasbourg, France
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Zhou F, Zhang H, Kulkarni SD, Lorsch JR, Hinnebusch AG. eIF1 discriminates against suboptimal initiation sites to prevent excessive uORF translation genome-wide. RNA (NEW YORK, N.Y.) 2020; 26:419-438. [PMID: 31915290 PMCID: PMC7075259 DOI: 10.1261/rna.073536.119] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/06/2020] [Indexed: 05/22/2023]
Abstract
The translation preinitiation complex (PIC) scans the mRNA for an AUG codon in a favorable context. Previous findings suggest that the factor eIF1 discriminates against non-AUG start codons by impeding full accommodation of Met-tRNAi in the P site of the 40S ribosomal subunit, necessitating eIF1 dissociation for start codon selection. Consistent with this, yeast eIF1 substitutions that weaken its binding to the PIC increase initiation at UUG codons on a mutant his4 mRNA and particular synthetic mRNA reporters; and also at the AUG start codon of the mRNA for eIF1 itself owing to its poor Kozak context. It was not known however whether such eIF1 mutants increase initiation at suboptimal start codons genome-wide. By ribosome profiling, we show that the eIF1-L96P variant confers increased translation of numerous upstream open reading frames (uORFs) initiating with either near-cognate codons (NCCs) or AUGs in poor context. The increased uORF translation is frequently associated with the reduced translation of the downstream main coding sequences (CDS). Initiation is also elevated at certain NCCs initiating amino-terminal extensions, including those that direct mitochondrial localization of the GRS1 and ALA1 products, and at a small set of main CDS AUG codons with especially poor context, including that of eIF1 itself. Thus, eIF1 acts throughout the yeast translatome to discriminate against NCC start codons and AUGs in poor context; and impairing this function enhances the repressive effects of uORFs on CDS translation and alters the ratios of protein isoforms translated from near-cognate versus AUG start codons.
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Affiliation(s)
- Fujun Zhou
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Hongen Zhang
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Shardul D Kulkarni
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jon R Lorsch
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Alan G Hinnebusch
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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15
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Kulkarni SD, Zhou F, Sen ND, Zhang H, Hinnebusch AG, Lorsch JR. Temperature-dependent regulation of upstream open reading frame translation in S. cerevisiae. BMC Biol 2019; 17:101. [PMID: 31810458 PMCID: PMC6898956 DOI: 10.1186/s12915-019-0718-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/01/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Translation of an mRNA in eukaryotes starts at an AUG codon in most cases, but near-cognate codons (NCCs) such as UUG, ACG, and AUU can also be used as start sites at low levels in Saccharomyces cerevisiae. Initiation from NCCs or AUGs in the 5'-untranslated regions (UTRs) of mRNAs can lead to translation of upstream open reading frames (uORFs) that might regulate expression of the main ORF (mORF). Although there is some circumstantial evidence that the translation of uORFs can be affected by environmental conditions, little is known about how it is affected by changes in growth temperature. RESULTS Using reporter assays, we found that changes in growth temperature can affect translation from NCC start sites in yeast cells, suggesting the possibility that gene expression could be regulated by temperature by altering use of different uORF start codons. Using ribosome profiling, we provide evidence that growth temperature regulates the efficiency of translation of nearly 200 uORFs in S. cerevisiae. Of these uORFs, most that start with an AUG codon have increased translational efficiency at 37 °C relative to 30 °C and decreased efficiency at 20 °C. For translationally regulated uORFs starting with NCCs, we did not observe a general trend for the direction of regulation as a function of temperature, suggesting mRNA-specific features can determine the mode of temperature-dependent regulation. Consistent with this conclusion, the position of the uORFs in the 5'-leader relative to the 5'-cap and the start codon of the main ORF correlates with the direction of temperature-dependent regulation of uORF translation. We have identified several novel cases in which changes in uORF translation are inversely correlated with changes in the translational efficiency of the downstream main ORF. Our data suggest that translation of these mRNAs is subject to temperature-dependent, uORF-mediated regulation. CONCLUSIONS Our data suggest that alterations in the translation of specific uORFs by temperature can regulate gene expression in S. cerevisiae.
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Affiliation(s)
- Shardul D Kulkarni
- Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Fujun Zhou
- Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Neelam Dabas Sen
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Present Address: School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Hongen Zhang
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Alan G Hinnebusch
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Jon R Lorsch
- Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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16
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Monteuuis G, Miścicka A, Świrski M, Zenad L, Niemitalo O, Wrobel L, Alam J, Chacinska A, Kastaniotis AJ, Kufel J. Non-canonical translation initiation in yeast generates a cryptic pool of mitochondrial proteins. Nucleic Acids Res 2019; 47:5777-5791. [PMID: 31216041 PMCID: PMC6582344 DOI: 10.1093/nar/gkz301] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 12/15/2022] Open
Abstract
Utilization of non-AUG alternative translation start sites is most common in bacteria and viruses, but it has been also reported in other organisms. This phenomenon increases proteome complexity by allowing expression of multiple protein isoforms from a single gene. In Saccharomyces cerevisiae, a few described cases concern proteins that are translated from upstream near-cognate start codons as N-terminally extended variants that localize to mitochondria. Using bioinformatics tools, we provide compelling evidence that in yeast the potential for producing alternative protein isoforms by non-AUG translation initiation is much more prevalent than previously anticipated and may apply to as many as a few thousand proteins. Several hundreds of candidates are predicted to gain a mitochondrial targeting signal (MTS), generating an unrecognized pool of mitochondrial proteins. We confirmed mitochondrial localization of a subset of proteins previously not identified as mitochondrial, whose standard forms do not carry an MTS. Our data highlight the potential of non-canonical translation initiation in expanding the capacity of the mitochondrial proteome and possibly also other cellular features.
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Affiliation(s)
- Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Anna Miścicka
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Michał Świrski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Lounis Zenad
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
| | - Olli Niemitalo
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Lidia Wrobel
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Jahangir Alam
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Agnieszka Chacinska
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland.,Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 5400, FIN-90014 Finland
| | - Joanna Kufel
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
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17
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Zheng GZ, Li W, Liu ZY. Alternative role of noncoding RNAs: coding and noncoding properties. J Zhejiang Univ Sci B 2019; 20:920-927. [PMID: 31595728 DOI: 10.1631/jzus.b1900336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Noncoding RNAs (ncRNAs) have played a critical role in cellular biological functions. Recently, some peptides or proteins originating from annotated ncRNAs were identified in organism development and various diseases. Here, we briefly review several novel peptides translated by annotated ncRNAs and related key functions. In addition, we summarize the potential mechanism of bifunctional ncRNAs and propose a specific "switch" triggering the transformation from the noncoding to the coding state under certain stimuli or cellular stress. The coding properties of ncRNAs and their peptide products may provide a novel horizon in proteomic research and can be regarded as a potential therapeutic target for the treatment of various diseases.
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Affiliation(s)
- Gui-Zhen Zheng
- Department of Emergency Internal Medicine, Shanghai East Hospital, Tongji University, Shanghai 200120, China
| | - Wei Li
- Department of General Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Zhi-Yong Liu
- Department of Laboratory Diagnostics, Changhai Hospital, Second Military Medical University, Shanghai 200433, China.,Kunming General Hospital of Chengdu Military Command, Kunming 650032, China
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18
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Lee YH, Lo YT, Chang CP, Yeh CS, Chang TH, Chen YW, Tseng YK, Wang CC. Naturally occurring dual recognition of tRNA His substrates with and without a universal identity element. RNA Biol 2019; 16:1275-1285. [PMID: 31179821 DOI: 10.1080/15476286.2019.1626663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The extra 5' guanine nucleotide (G-1) on tRNAHis is a nearly universal feature that specifies tRNAHis identity. The G-1 residue is either genome encoded or post-transcriptionally added by tRNAHis guanylyltransferase (Thg1). Despite Caenorhabditis elegans being a Thg1-independent organism, its cytoplasmic tRNAHis (CetRNAnHis) retains a genome-encoded G-1. Our study showed that this eukaryote possesses a histidyl-tRNA synthetase (CeHisRS) gene encoding two distinct HisRS isoforms that differ only at their N-termini. Most interestingly, its mitochondrial tRNAHis (CetRNAmHis) lacks G-1, a scenario never observed in any organelle. This tRNA, while lacking the canonical identity element, can still be efficiently aminoacylated in vivo. Even so, addition of G-1 to CetRNAmHis strongly enhanced its aminoacylation efficiency in vitro. Overexpression of CeHisRS successfully bypassed the requirement for yeast THG1 in the presence of CetRNAnHis without G-1. Mutagenesis assays showed that the anticodon takes a primary role in CetRNAHis identity recognition, being comparable to the universal identity element. Consequently, simultaneous introduction of both G-1 and the anticodon of tRNAHis effectively converted a non-cognate tRNA to a tRNAHis-like substrate. Our study suggests that a new balance between identity elements of tRNAHis relieves HisRS from the absolute requirement for G-1.
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Affiliation(s)
- Yi-Hsueh Lee
- a Department of Life Sciences, National Central University , Taoyuan , Taiwan
| | - Ya-Ting Lo
- a Department of Life Sciences, National Central University , Taoyuan , Taiwan
| | - Chia-Pei Chang
- a Department of Life Sciences, National Central University , Taoyuan , Taiwan
| | - Chung-Shu Yeh
- b Genomics Research Center, Academia Sinica , Taipei , Taiwan
| | | | - Yu-Wei Chen
- c Department of Neurology, Landseed International Hospital , Taoyuan , Taiwan
| | - Yi-Kuan Tseng
- d Graduate Institute of Statistics, National Central University , Taoyuan , Taiwan
| | - Chien-Chia Wang
- a Department of Life Sciences, National Central University , Taoyuan , Taiwan
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19
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Heublein M, Ndi M, Vazquez-Calvo C, Vögtle FN, Ott M. Alternative Translation Initiation at a UUG Codon Gives Rise to Two Functional Variants of the Mitochondrial Protein Kgd4. J Mol Biol 2019; 431:1460-1467. [DOI: 10.1016/j.jmb.2019.02.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/10/2019] [Accepted: 02/19/2019] [Indexed: 11/15/2022]
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20
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Crawford RA, Pavitt GD. Translational regulation in response to stress in Saccharomyces cerevisiae. Yeast 2018; 36:5-21. [PMID: 30019452 PMCID: PMC6492140 DOI: 10.1002/yea.3349] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/08/2018] [Accepted: 06/25/2018] [Indexed: 12/19/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae must dynamically alter the composition of its proteome in order to respond to diverse stresses. The reprogramming of gene expression during stress typically involves initial global repression of protein synthesis, accompanied by the activation of stress‐responsive mRNAs through both translational and transcriptional responses. The ability of specific mRNAs to counter the global translational repression is therefore crucial to the overall response to stress. Here we summarize the major repressive mechanisms and discuss mechanisms of translational activation in response to different stresses in S. cerevisiae. Taken together, a wide range of studies indicate that multiple elements act in concert to bring about appropriate translational responses. These include regulatory elements within mRNAs, altered mRNA interactions with RNA‐binding proteins and the specialization of ribosomes that each contribute towards regulating protein expression to suit the changing environmental conditions.
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Affiliation(s)
- Robert A Crawford
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Michael Smith Building, Dover Street, Manchester, M13 9PT, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Michael Smith Building, Dover Street, Manchester, M13 9PT, UK
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21
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Ryoo HD, Vasudevan D. Two distinct nodes of translational inhibition in the Integrated Stress Response. BMB Rep 2018; 50:539-545. [PMID: 28803610 PMCID: PMC5720466 DOI: 10.5483/bmbrep.2017.50.11.157] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Indexed: 12/21/2022] Open
Abstract
The Integrated Stress Response (ISR) refers to a signaling pathway initiated by stress-activated eIF2α kinases. Once activated, the pathway causes attenuation of global mRNA translation while also paradoxically inducing stress response gene expression. A detailed analysis of this pathway has helped us better understand how stressed cells coordinate gene expression at translational and transcriptional levels. The translational attenuation associated with this pathway has been largely attributed to the phosphorylation of the translational initiation factor eIF2α. However, independent studies are now pointing to a second translational regulation step involving a downstream ISR target, 4E-BP, in the inhibition of eIF4E and specifically cap-dependent translation. The activation of 4E-BP is consistent with previous reports implicating the roles of 4E-BP resistant, Internal Ribosome Entry Site (IRES) dependent translation in ISR active cells. In this review, we provide an overview of the translation inhibition mechanisms engaged by the ISR and how they impact the translation of stress response genes.
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Affiliation(s)
- Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Deepika Vasudevan
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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22
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Abstract
This review by Kearse and Wilusz discusses the profound impact of non-AUG start codons in eukaryotic translation. It describes how misregulation of non-AUG initiation events contributes to multiple human diseases, including cancer and neurodegeneration, and how modulation of non-AUG usage may represent a novel therapeutic strategy. Although it was long thought that eukaryotic translation almost always initiates at an AUG start codon, recent advancements in ribosome footprint mapping have revealed that non-AUG start codons are used at an astonishing frequency. These non-AUG initiation events are not simply errors but instead are used to generate or regulate proteins with key cellular functions; for example, during development or stress. Misregulation of non-AUG initiation events contributes to multiple human diseases, including cancer and neurodegeneration, and modulation of non-AUG usage may represent a novel therapeutic strategy. It is thus becoming increasingly clear that start codon selection is regulated by many trans-acting initiation factors as well as sequence/structural elements within messenger RNAs and that non-AUG translation has a profound impact on cellular states.
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Affiliation(s)
- Michael G Kearse
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, 19104 USA
| | - Jeremy E Wilusz
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, 19104 USA
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23
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Kritsiligkou P, Chatzi A, Charalampous G, Mironov A, Grant CM, Tokatlidis K. Unconventional Targeting of a Thiol Peroxidase to the Mitochondrial Intermembrane Space Facilitates Oxidative Protein Folding. Cell Rep 2017; 18:2729-2741. [PMID: 28297675 PMCID: PMC5368413 DOI: 10.1016/j.celrep.2017.02.053] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/01/2016] [Accepted: 02/16/2017] [Indexed: 02/06/2023] Open
Abstract
Thiol peroxidases are conserved hydrogen peroxide scavenging and signaling molecules that contain redox-active cysteine residues. We show here that Gpx3, the major H2O2 sensor in yeast, is present in the mitochondrial intermembrane space (IMS), where it serves a compartment-specific role in oxidative metabolism. The IMS-localized Gpx3 contains an 18-amino acid N-terminally extended form encoded from a non-AUG codon. This acts as a mitochondrial targeting signal in a pathway independent of the hitherto known IMS-import pathways. Mitochondrial Gpx3 interacts with the Mia40 oxidoreductase in a redox-dependent manner and promotes efficient Mia40-dependent oxidative protein folding. We show that cells lacking Gpx3 have aberrant mitochondrial morphology, defective protein import capacity, and lower inner membrane potential, all of which can be rescued by expression of a mitochondrial-only form of Gpx3. Together, our data reveal a novel role for Gpx3 in mitochondrial redox regulation and protein homeostasis. A pool of yeast Gpx3 localizes to mitochondria via translation from a non-AUG codon Loss of Gpx3 causes defects in mitochondrial architecture and membrane potential Gpx3 interacts with the oxidative protein folding machinery in the IMS
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Affiliation(s)
- Paraskevi Kritsiligkou
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | - Afroditi Chatzi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Georgia Charalampous
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Aleksandr Mironov
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | - Chris M Grant
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK.
| | - Kostas Tokatlidis
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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24
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Lee YH, Chang CP, Cheng YJ, Kuo YY, Lin YS, Wang CC. Evolutionary gain of highly divergent tRNA specificities by two isoforms of human histidyl-tRNA synthetase. Cell Mol Life Sci 2017; 74:2663-2677. [PMID: 28321488 PMCID: PMC11107585 DOI: 10.1007/s00018-017-2491-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 02/16/2017] [Accepted: 02/20/2017] [Indexed: 11/28/2022]
Abstract
The discriminator base N73 is a key identity element of tRNAHis. In eukaryotes, N73 is an "A" in cytoplasmic tRNAHis and a "C" in mitochondrial tRNAHis. We present evidence herein that yeast histidyl-tRNA synthetase (HisRS) recognizes both A73 and C73, but somewhat prefers A73 even within the context of mitochondrial tRNAHis. In contrast, humans possess two distinct yet closely related HisRS homologues, with one encoding the cytoplasmic form (with an extra N-terminal WHEP domain) and the other encoding its mitochondrial counterpart (with an extra N-terminal mitochondrial targeting signal). Despite these two isoforms sharing high sequence similarities (81% identity), they strongly preferred different discriminator bases (A73 or C73). Moreover, only the mitochondrial form recognized the anticodon as a strong identity element. Most intriguingly, swapping the discriminator base between the cytoplasmic and mitochondrial tRNAHis isoacceptors conveniently switched their enzyme preferences. Similarly, swapping seven residues in the active site between the two isoforms readily switched their N73 preferences. This study suggests that the human HisRS genes, while descending from a common ancestor with dual function for both types of tRNAHis, have acquired highly specialized tRNA recognition properties through evolution.
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Affiliation(s)
- Yi-Hsueh Lee
- Department of Life Sciences, National Central University, Jungli District, Taoyuan, 32001, Taiwan
| | - Chia-Pei Chang
- Department of Life Sciences, National Central University, Jungli District, Taoyuan, 32001, Taiwan
| | - Yu-Ju Cheng
- Department of Life Sciences, National Central University, Jungli District, Taoyuan, 32001, Taiwan
| | - Yi-Yi Kuo
- Department of Life Sciences, National Central University, Jungli District, Taoyuan, 32001, Taiwan
| | - Yeong-Shin Lin
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, 30068, Taiwan
| | - Chien-Chia Wang
- Department of Life Sciences, National Central University, Jungli District, Taoyuan, 32001, Taiwan.
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25
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Mechanism and Regulation of Protein Synthesis in Saccharomyces cerevisiae. Genetics 2017; 203:65-107. [PMID: 27183566 DOI: 10.1534/genetics.115.186221] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/24/2016] [Indexed: 12/18/2022] Open
Abstract
In this review, we provide an overview of protein synthesis in the yeast Saccharomyces cerevisiae The mechanism of protein synthesis is well conserved between yeast and other eukaryotes, and molecular genetic studies in budding yeast have provided critical insights into the fundamental process of translation as well as its regulation. The review focuses on the initiation and elongation phases of protein synthesis with descriptions of the roles of translation initiation and elongation factors that assist the ribosome in binding the messenger RNA (mRNA), selecting the start codon, and synthesizing the polypeptide. We also examine mechanisms of translational control highlighting the mRNA cap-binding proteins and the regulation of GCN4 and CPA1 mRNAs.
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26
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Debard S, Bader G, De Craene JO, Enkler L, Bär S, Laporte D, Hammann P, Myslinski E, Senger B, Friant S, Becker HD. Nonconventional localizations of cytosolic aminoacyl-tRNA synthetases in yeast and human cells. Methods 2017; 113:91-104. [DOI: 10.1016/j.ymeth.2016.09.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 11/26/2022] Open
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27
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The Role of FNDC5/Irisin in the Nervous System and as a Mediator for Beneficial Effects of Exercise on the Brain. RESEARCH AND PERSPECTIVES IN ENDOCRINE INTERACTIONS 2017. [DOI: 10.1007/978-3-319-72790-5_8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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28
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Kastaniotis AJ, Autio KJ, Kerätär JM, Monteuuis G, Mäkelä AM, Nair RR, Pietikäinen LP, Shvetsova A, Chen Z, Hiltunen JK. Mitochondrial fatty acid synthesis, fatty acids and mitochondrial physiology. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:39-48. [PMID: 27553474 DOI: 10.1016/j.bbalip.2016.08.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/20/2016] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
Abstract
Mitochondria and fatty acids are tightly connected to a multiplicity of cellular processes that go far beyond mitochondrial fatty acid metabolism. In line with this view, there is hardly any common metabolic disorder that is not associated with disturbed mitochondrial lipid handling. Among other aspects of mitochondrial lipid metabolism, apparently all eukaryotes are capable of carrying out de novo fatty acid synthesis (FAS) in this cellular compartment in an acyl carrier protein (ACP)-dependent manner. The dual localization of FAS in eukaryotic cells raises the questions why eukaryotes have maintained the FAS in mitochondria in addition to the "classic" cytoplasmic FAS and what the products are that cannot be substituted by delivery of fatty acids of extramitochondrial origin. The current evidence indicates that mitochondrial FAS is essential for cellular respiration and mitochondrial biogenesis. Although both β-oxidation and FAS utilize thioester chemistry, CoA acts as acyl-group carrier in the breakdown pathway whereas ACP assumes this role in the synthetic direction. This arrangement metabolically separates these two pathways running towards opposite directions and prevents futile cycling. A role of this pathway in mitochondrial metabolic sensing has recently been proposed. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland.
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Juha M Kerätär
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Anne M Mäkelä
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Remya R Nair
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Laura P Pietikäinen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Zhijun Chen
- State Key Laboratory of Supramolecular Structure and Materials and Institute of Theoretical Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland; State Key Laboratory of Supramolecular Structure and Materials and Institute of Theoretical Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.
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29
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Chang CY, Chang CP, Chakraborty S, Wang SW, Tseng YK, Wang CC. Modulating the Structure and Function of an Aminoacyl-tRNA Synthetase Cofactor by Biotinylation. J Biol Chem 2016; 291:17102-11. [PMID: 27330079 DOI: 10.1074/jbc.m116.734343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Indexed: 12/20/2022] Open
Abstract
Arc1p is a yeast-specific tRNA-binding protein that forms a ternary complex with glutamyl-tRNA synthetase (GluRSc) and methionyl-tRNA synthetase (MetRS) in the cytoplasm to regulate their catalytic activities and subcellular distributions. Despite Arc1p not being involved in any known biotin-dependent reaction, it is a natural target of biotin modification. Results presented herein show that biotin modification had no obvious effect on the growth-supporting activity, subcellular distribution, tRNA binding, or interactions of Arc1p with GluRSc and MetRS. Nevertheless, biotinylation of Arc1p was temperature dependent; raising the growth temperature from 30 to 37 °C drastically reduced its biotinylation level. As a result, Arc1p purified from a yeast culture that had been grown overnight at 37 °C was essentially biotin free. Non-biotinylated Arc1p was more heat stable, more flexible in structure, and more effective than its biotinylated counterpart in promoting glutamylation activity of the otherwise inactive GluRSc at 37 °C in vitro Our study suggests that the structure and function of Arc1p can be modulated via biotinylation in response to temperature changes.
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Affiliation(s)
| | | | - Shruti Chakraborty
- the Department of Biotechnology, University of Calcutta, Kolkata 700019, India, and
| | - Shao-Win Wang
- the Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan Town, Miaoli 35053, Taiwan
| | - Yi-Kuan Tseng
- the Graduate Institute of Statistics, National Central University, Jungli District, Taoyuan 32001, Taiwan
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30
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Chang CY, Chien CI, Chang CP, Lin BC, Wang CC. A WHEP Domain Regulates the Dynamic Structure and Activity of Caenorhabditis elegans Glycyl-tRNA Synthetase. J Biol Chem 2016; 291:16567-75. [PMID: 27298321 DOI: 10.1074/jbc.m116.730812] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Indexed: 11/06/2022] Open
Abstract
WHEP domains exist in certain eukaryotic aminoacyl-tRNA synthetases and play roles in tRNA or protein binding. We present evidence herein that cytoplasmic and mitochondrial forms of Caenorhabditis elegans glycyl-tRNA synthetase (CeGlyRS) are encoded by the same gene (CeGRS1) through alternative initiation of translation. The cytoplasmic form possessed an N-terminal WHEP domain, whereas its mitochondrial isoform possessed an extra N-terminal sequence consisting of an mitochondrial targeting signal and an appended domain. Cross-species complementation assays showed that CeGRS1 effectively rescued the cytoplasmic and mitochondrial defects of a yeast GRS1 knock-out strain. Although both forms of CeGlyRS efficiently charged the cytoplasmic tRNAs(Gly) of C. elegans, the mitochondrial form was much more efficient than its cytoplasmic counterpart in charging the mitochondrial tRNA(Gly) isoacceptor, which carries a defective TψC hairpin. Despite the WHEP domain per se lacking tRNA binding activity, deletion of this domain reduced the catalytic efficiency of the enzyme. Most interestingly, the deletion mutant possessed a higher thermal stability and a somewhat lower structural flexibility. Our study suggests a role for the WHEP domain as a regulator of the dynamic structure and activity of the enzyme.
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Affiliation(s)
- Chih-Yao Chang
- From the Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Chin-I Chien
- From the Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Chia-Pei Chang
- From the Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Bo-Chun Lin
- From the Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Chien-Chia Wang
- From the Department of Life Sciences, National Central University, Taoyuan 32001, Taiwan
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31
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Thiaville PC, Legendre R, Rojas-Benítez D, Baudin-Baillieu A, Hatin I, Chalancon G, Glavic A, Namy O, de Crécy-Lagard V. Global translational impacts of the loss of the tRNA modification t 6A in yeast. MICROBIAL CELL 2016; 3:29-45. [PMID: 26798630 PMCID: PMC4717488 DOI: 10.15698/mic2016.01.473] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The universal tRNA modification t6A is found at position 37 of nearly
all tRNAs decoding ANN codons. The absence of t6A37 leads
to severe growth defects in baker’s yeast, phenotypes similar to those caused by
defects in mcm5s2U34 synthesis. Mutants in
mcm5s2U34 can be suppressed by
overexpression of tRNALysUUU, but we show t6A
phenotypes could not be suppressed by expressing any individual ANN decoding
tRNA, and t6A and mcm5s2U are not determinants
for each other’s formation. Our results suggest that t6A deficiency,
like mcm5s2U deficiency, leads to protein folding defects,
and show that the absence of t6A led to stress sensitivities (heat,
ethanol, salt) and sensitivity to TOR pathway inhibitors. Additionally,
L-homoserine suppressed the slow growth phenotype seen in
t6A-deficient strains, and proteins aggregates and Advanced Glycation
End-products (AGEs) were increased in the mutants. The global consequences on
translation caused by t6A absence were examined by ribosome
profiling. Interestingly, the absence of t6A did not lead to global
translation defects, but did increase translation initiation at upstream non-AUG
codons and increased frame-shifting in specific genes. Analysis of codon
occupancy rates suggests that one of the major roles of t6A is to
homogenize the process of elongation by slowing the elongation rate at codons
decoded by high abundance tRNAs and I34:C3 pairs while
increasing the elongation rate of rare tRNAs and G34:U3
pairs. This work reveals that the consequences of t6A absence are
complex and multilayered and has set the stage to elucidate the molecular basis
of the observed phenotypes.
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Affiliation(s)
- Patrick C Thiaville
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA; Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL 32610, USA; University of Florida Genetics Institute, University of Florida, Gainesville, FL 32610, USA; Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Rachel Legendre
- Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Diego Rojas-Benítez
- Centro de Regulación del Genoma. Facultad de Ciencias - Universidad de Chile, Santiago, Chile
| | - Agnès Baudin-Baillieu
- Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Isabelle Hatin
- Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Guilhem Chalancon
- Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Alvaro Glavic
- Centro de Regulación del Genoma. Facultad de Ciencias - Universidad de Chile, Santiago, Chile
| | - Olivier Namy
- Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA; University of Florida Genetics Institute, University of Florida, Gainesville, FL 32610, USA
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32
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Smac mimetic with TNF-α targets Pim-1 isoforms and reactive oxygen species production to abrogate transformation from blebbishields. Biochem J 2015; 473:99-107. [PMID: 26508734 DOI: 10.1042/bj20150877] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 10/27/2015] [Indexed: 01/10/2023]
Abstract
Cancer cells are capable of sphere formation (transformation) through reactive oxygen species (ROS) and glycolysis shift. Transformation is linked to tumorigenesis and therapy resistance, hence targeting regulators of ROS and glycolysis is important for cancer therapeutic candidates. Here, we demonstrate that Smac mimetic AZ58 in combination with tumour necrosis factor-α (TNF-α) was able to inhibit the production of ROS, inhibit glycolysis through Pim-1 kinase-mediated Ser-112 phosphorylation of BAD, and increase depolarization of mitochondria. We also identified mitochondrial isoforms of Pim-1 kinase that were targeted for degradation by AZ58 in combination with TNF-α or AZ58 in combination with Fas ligand (FasL) plus cycloheximide (CHX) through caspase-3 to block transformation. Our study demonstrates that Smac mimetic in combination with TNF-α is an ideal candidate to target Pim-1 expression, inhibit ROS production and to block transformation from blebbishields.
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33
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Ribosome profiling reveals the what, when, where and how of protein synthesis. Nat Rev Mol Cell Biol 2015; 16:651-64. [PMID: 26465719 DOI: 10.1038/nrm4069] [Citation(s) in RCA: 309] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Ribosome profiling, which involves the deep sequencing of ribosome-protected mRNA fragments, is a powerful tool for globally monitoring translation in vivo. The method has facilitated discovery of the regulation of gene expression underlying diverse and complex biological processes, of important aspects of the mechanism of protein synthesis, and even of new proteins, by providing a systematic approach for experimental annotation of coding regions. Here, we introduce the methodology of ribosome profiling and discuss examples in which this approach has been a key factor in guiding biological discovery, including its prominent role in identifying thousands of novel translated short open reading frames and alternative translation products.
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34
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Jedrychowski MP, Wrann CD, Paulo JA, Gerber KK, Szpyt J, Robinson MM, Nair KS, Gygi SP, Spiegelman BM. Detection and Quantitation of Circulating Human Irisin by Tandem Mass Spectrometry. Cell Metab 2015; 22:734-740. [PMID: 26278051 PMCID: PMC4802359 DOI: 10.1016/j.cmet.2015.08.001] [Citation(s) in RCA: 362] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 07/29/2015] [Accepted: 08/04/2015] [Indexed: 01/08/2023]
Abstract
Exercise provides many health benefits, including improved metabolism, cardiovascular health, and cognition. We have shown previously that FNDC5, a type I transmembrane protein, and its circulating form, irisin, convey some of these benefits in mice. However, recent reports questioned the existence of circulating human irisin both because human FNDC5 has a non-canonical ATA translation start and because of claims that many human irisin antibodies used in commercial ELISA kits lack required specificity. In this paper we have identified and quantitated human irisin in plasma using mass spectrometry with control peptides enriched with heavy stable isotopes as internal standards. This precise state-of-the-art method shows that human irisin is mainly translated from its non-canonical start codon and circulates at ∼ 3.6 ng/ml in sedentary individuals; this level is increased to ∼ 4.3 ng/ml in individuals undergoing aerobic interval training. These data unequivocally demonstrate that human irisin exists, circulates, and is regulated by exercise.
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Affiliation(s)
- Mark P Jedrychowski
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.,Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, MA 02115
| | - Christiane D Wrann
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, MA 02115
| | - Kaitlyn K Gerber
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
| | - John Szpyt
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, MA 02115
| | - Matthew M Robinson
- Division of Endocrinology, 200 First Street SW, Joseph 5-193, Mayo Clinic, Rochester, MN 55905
| | - K Sreekumaran Nair
- Division of Endocrinology, 200 First Street SW, Joseph 5-193, Mayo Clinic, Rochester, MN 55905
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue Boston, MA 02115
| | - Bruce M Spiegelman
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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35
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Yanagida H, Gispan A, Kadouri N, Rozen S, Sharon M, Barkai N, Tawfik DS. The Evolutionary Potential of Phenotypic Mutations. PLoS Genet 2015; 11:e1005445. [PMID: 26244544 PMCID: PMC4526572 DOI: 10.1371/journal.pgen.1005445] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 07/15/2015] [Indexed: 01/08/2023] Open
Abstract
Errors in protein synthesis, so-called phenotypic mutations, are orders-of-magnitude more frequent than genetic mutations. Here, we provide direct evidence that alternative protein forms and phenotypic variability derived from translational errors paved the path to genetic, evolutionary adaptations via gene duplication. We explored the evolutionary origins of Saccharomyces cerevisiae IDP3 - an NADP-dependent isocitrate dehydrogenase mediating fatty acids ß-oxidation in the peroxisome. Following the yeast whole genome duplication, IDP3 diverged from a cytosolic ancestral gene by acquisition of a C-terminal peroxisomal targeting signal. We discovered that the pre-duplicated cytosolic IDPs are partially localized to the peroxisome owing to +1 translational frameshifts that bypass the stop codon and unveil cryptic peroxisomal targeting signals within the 3'-UTR. Exploring putative cryptic signals in all 3'-UTRs of yeast genomes, we found that other enzymes related to NADPH production such as pyruvate carboxylase 1 (PYC1) might be prone to peroxisomal localization via cryptic signals. Using laboratory evolution we found that these translational frameshifts are rapidly imprinted via genetic single base deletions occurring within the very same gene location. Further, as exemplified here, the sequences that promote translational frameshifts are also more prone to genetic deletions. Thus, genotypes conferring higher phenotypic variability not only meet immediate challenges by unveiling cryptic 3'-UTR sequences, but also boost the potential for future genetic adaptations.
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Affiliation(s)
- Hayato Yanagida
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Ariel Gispan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Noam Kadouri
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shelly Rozen
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Sharon
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dan S. Tawfik
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
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36
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Chang CP, Chang CY, Lee YH, Lin YS, Wang CC. Divergent Alanyl-tRNA Synthetase Genes of Vanderwaltozyma polyspora Descended from a Common Ancestor through Whole-Genome Duplication Followed by Asymmetric Evolution. Mol Cell Biol 2015; 35:2242-53. [PMID: 25896914 PMCID: PMC4456443 DOI: 10.1128/mcb.00018-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/14/2015] [Accepted: 04/14/2015] [Indexed: 11/20/2022] Open
Abstract
Cytoplasmic and mitochondrial forms of a eukaryotic aminoacyl-tRNA synthetase (aaRS) are generally encoded by two distinct nuclear genes, one of eukaryotic origin and the other of mitochondrial origin. However, in most known yeasts, only the mitochondrial-origin alanyl-tRNA synthetase (AlaRS) gene is retained and plays a dual-functional role. Here, we present a novel scenario of AlaRS evolution in the yeast Vanderwaltozyma polyspora. V. polyspora possesses two significantly diverged AlaRS gene homologues, one encoding the cytoplasmic form and the other its mitochondrial counterpart. Clever selection of transcription and translation initiation sites enables the two isoforms to be localized and thus functional in their respective cellular compartments. However, the two isoforms can also be stably expressed and function in the reciprocal compartments by insertion or removal of a mitochondrial targeting signal. Synteny and phylogeny analyses revealed that the AlaRS homologues of V. polyspora arose from a dual-functional common ancestor through whole-genome duplication (WGD). Moreover, the mitochondrial form had higher synonymous (1.6-fold) and nonsynonymous (2.8-fold) substitution rates than did its cytoplasmic counterpart, presumably due to a lesser constraint imposed on components of the mitochondrial translational apparatus. Our study suggests that asymmetric evolution confers the divergence between the AlaRS paralogues of V. polyspora.
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Affiliation(s)
- Chia-Pei Chang
- Department of Life Sciences, National Central University, Jungli, Taiwan
| | - Chih-Yao Chang
- Department of Life Sciences, National Central University, Jungli, Taiwan
| | - Yi-Hsueh Lee
- Department of Life Sciences, National Central University, Jungli, Taiwan
| | - Yeong-Shin Lin
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsin-Chu, Taiwan
| | - Chien-Chia Wang
- Department of Life Sciences, National Central University, Jungli, Taiwan
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37
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Scoles DR, Ho MHT, Dansithong W, Pflieger LT, Petersen LW, Thai KK, Pulst SM. Repeat Associated Non-AUG Translation (RAN Translation) Dependent on Sequence Downstream of the ATXN2 CAG Repeat. PLoS One 2015; 10:e0128769. [PMID: 26086378 PMCID: PMC4472729 DOI: 10.1371/journal.pone.0128769] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 05/01/2015] [Indexed: 11/18/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is a progressive autosomal dominant disorder caused by the expansion of a CAG tract in the ATXN2 gene. The SCA2 disease phenotype is characterized by cerebellar atrophy, gait ataxia, and slow saccades. ATXN2 mutation causes gains of toxic and normal functions of the ATXN2 gene product, ataxin-2, and abnormally slow Purkinje cell firing frequency. Previously we investigated features of ATXN2 controlling expression and noted expression differences for ATXN2 constructs with varying CAG lengths, suggestive of repeat associated non-AUG translation (RAN translation). To determine whether RAN translation occurs for ATXN2 we assembled various ATXN2 constructs with ATXN2 tagged by luciferase, HA or FLAG tags, driven by the CMV promoter or the ATXN2 promoter. Luciferase expression from ATXN2-luciferase constructs lacking the ATXN2 start codon was weak vs AUG translation, regardless of promoter type, and did not increase with longer CAG repeat lengths. RAN translation was detected on western blots by the anti-polyglutamine antibody 1C2 for constructs driven by the CMV promoter but not the ATXN2 promoter, and was weaker than AUG translation. Strong RAN translation was also observed when driving the ATXN2 sequence with the CMV promoter with ATXN2 sequence downstream of the CAG repeat truncated to 18 bp in the polyglutamine frame but not in the polyserine or polyalanine frames. Our data demonstrate that ATXN2 RAN translation is weak compared to AUG translation and is dependent on ATXN2 sequences flanking the CAG repeat.
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Affiliation(s)
- Daniel R. Scoles
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
- * E-mail:
| | - Mi H. T. Ho
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
| | - Warunee Dansithong
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
| | - Lance T. Pflieger
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
| | - Lance W. Petersen
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
| | - Khanh K. Thai
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, 84132, United States of America
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38
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Vanderwaltozyma polyspora possesses two glycyl-tRNA synthetase genes: one constitutive and one inducible. Fungal Genet Biol 2015; 76:47-56. [PMID: 25683380 DOI: 10.1016/j.fgb.2015.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/14/2015] [Accepted: 02/02/2015] [Indexed: 11/22/2022]
Abstract
Aminoacyl-tRNA synthetases are housekeeping enzymes essential for protein synthesis. We herein present evidence that the yeast Vanderwaltozyma polyspora possesses two paralogous glycyl-tRNA synthetase (GlyRS) genes-GRS1 and GRS2. Paradoxically, GRS1 provided functions in both the cytoplasm and mitochondria, while GRS2 was essentially silent under normal growth conditions. Expression of GRS2 could be activated by stresses such as high pH or ethanol and most effectively by high temperature. The expressed GlyRS2 protein was exclusively found in the cytoplasm and more stable under heat-shock conditions (37°C) than under normal growth conditions (30°C) in vivo. In addition, GRS2 effectively rescued the cytoplasmic defect of a Saccharomyces cerevisiae GRS1 knockout strain when expressed from a constitutive promoter. Moreover, the purified GlyRS2 enzyme was fairly active at both 30°C and 37°C in glycylation of yeast tRNA in vitro. However, unexpectedly, the purified GlyRS2 enzyme was practically inactive at temperature above 40°C in vitro. Our study suggests that GRS2 is an inducible gene that acts under stress conditions where GlyRS1 may be insufficient, unavailable, or rendered inactive.
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39
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Wrann CD. FNDC5/irisin - their role in the nervous system and as a mediator for beneficial effects of exercise on the brain. Brain Plast 2015; 1:55-61. [PMID: 28480165 PMCID: PMC5419585 DOI: 10.3233/bpl-150019] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Exercise can improve cognitive function and the outcome of neurodegenerative diseases, like Alzheimer's disease. This effect has been linked to the increased expression of brain-derived neurotrophic factor (BDNF). However, the underlying molecular mechanisms driving the elevation of this neurotrophin remain unknown. Recently, we have reported a PGC-1α-FNDC5/irisin pathway, which is activated by exercise in the hippocampus in mice and induces a neuroprotective gene program, including Bdnf. This review will focus on FNDC5 and its secreted form "irisin", a newly discovered myokine, and their role in the nervous system and its therapeutic potential. In addition, we will briefly discuss the role of other exercise-induced myokines on positive brain effects.
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Affiliation(s)
- Christiane D. Wrann
- Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, USA
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40
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Suomi F, Menger KE, Monteuuis G, Naumann U, Kursu VAS, Shvetsova A, Kastaniotis AJ. Expression and evolution of the non-canonically translated yeast mitochondrial acetyl-CoA carboxylase Hfa1p. PLoS One 2014; 9:e114738. [PMID: 25503745 PMCID: PMC4263661 DOI: 10.1371/journal.pone.0114738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 11/13/2014] [Indexed: 12/16/2022] Open
Abstract
The Saccharomyces cerevisiae genome encodes two sequence related acetyl-CoA carboxylases, the cytosolic Acc1p and the mitochondrial Hfa1p, required for respiratory function. Several aspects of expression of the HFA1 gene and its evolutionary origin have remained unclear. Here, we determined the HFA1 transcription initiation sites by 5' RACE analysis. Using a novel "Stop codon scanning" approach, we mapped the location of the HFA1 translation initiation site to an upstream AUU codon at position -372 relative to the annotated start codon. This upstream initiation leads to production of a mitochondrial targeting sequence preceding the ACC domains of the protein. In silico analyses of fungal ACC genes revealed conserved "cryptic" upstream mitochondrial targeting sequences in yeast species that have not undergone a whole genome duplication. Our Δhfa1 baker's yeast mutant phenotype rescue studies using the protoploid Kluyveromyces lactis ACC confirmed functionality of the cryptic upstream mitochondrial targeting signal. These results lend strong experimental support to the hypothesis that the mitochondrial and cytosolic acetyl-CoA carboxylases in S. cerevisiae have evolved from a single gene encoding both the mitochondrial and cytosolic isoforms. Leaning on a cursory survey of a group of genes of our interest, we propose that cryptic 5' upstream mitochondrial targeting sequences may be more abundant in eukaryotes than anticipated thus far.
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Affiliation(s)
- Fumi Suomi
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Katja E Menger
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Uta Naumann
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - V A Samuli Kursu
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
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41
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Functional substitution of a eukaryotic glycyl-tRNA synthetase with an evolutionarily unrelated bacterial cognate enzyme. PLoS One 2014; 9:e94659. [PMID: 24743154 PMCID: PMC3990555 DOI: 10.1371/journal.pone.0094659] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/18/2014] [Indexed: 12/03/2022] Open
Abstract
Two oligomeric types of glycyl-tRNA synthetase (GlyRS) are found in nature: a α2 type and a α2β2 type. The former has been identified in all three kingdoms of life and often pairs with tRNAGly that carries an A73 discriminator base, while the latter is found only in bacteria and chloroplasts and is almost always coupled with tRNAGly that contains U73. In the yeast Saccharomyces cerevisiae, a single GlyRS gene, GRS1, provides both the cytoplasmic and mitochondrial functions, and tRNAGly isoacceptors in both compartments possess A73. We showed herein that Homo sapiens and Arabidopsis thaliana cytoplasmic GlyRSs (both α2-type enzymes) can rescue both the cytoplasmic and mitochondrial defects of a yeast grs1- strain, while Escherichia coli GlyRS (a α2β2-type enzyme) and A. thaliana organellar GlyRS (a (αβ)2-type enzyme) failed to rescue either defect of the yeast mull allele. However, a head-to-tail αβ fusion of E. coli GlyRS effectively supported the mitochondrial function. Our study suggests that a α2-type eukaryotic GlyRS may be functionally substituted with a α2β2-type bacterial cognate enzyme despite their remote evolutionary relationships.
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42
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Sleigh JN, Grice SJ, Burgess RW, Talbot K, Cader MZ. Neuromuscular junction maturation defects precede impaired lower motor neuron connectivity in Charcot-Marie-Tooth type 2D mice. Hum Mol Genet 2013; 23:2639-50. [PMID: 24368416 DOI: 10.1093/hmg/ddt659] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dominant mutations in GARS, encoding the essential enzyme glycyl-tRNA synthetase (GlyRS), result in a form of Charcot-Marie-Tooth disease, type 2D (CMT2D), predominantly characterized by lower motor nerve degeneration. GlyRS charges the amino acid glycine with its cognate tRNA and is therefore essential for protein translation. However, the underlying mechanisms linking toxic gain-of-function GARS mutations to lower motor neuron degeneration remain unidentified. The neuromuscular junction (NMJ) appears to be an early target for pathology in a number of peripheral nerve diseases and becomes denervated at later stages in two mouse models of CMT2D. We therefore performed a detailed longitudinal examination of NMJs in the distal lumbrical muscles and the proximal transversus abdominis (TVA) muscles of wild-type and Gars mutant mice. We determined that mutant lumbrical NMJs display a persistent defect in maturation that precedes a progressive, age-dependent degeneration. Conversely, the TVA remains relatively unaffected, with only a subtle, short-lived impairment in pre- and post-synaptic development and no reduction in lower motor neuron connectivity to muscle. Together, these observations suggest that mutant Gars is associated with compromised development of the NMJ prior to synaptic degeneration and highlight the neuromuscular synapse as an important site of early, selective pathology in CMT2D mice.
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An insertion peptide in yeast glycyl-tRNA synthetase facilitates both productive docking and catalysis of cognate tRNAs. Mol Cell Biol 2013; 33:3515-23. [PMID: 23816885 DOI: 10.1128/mcb.00122-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The yeast Saccharomyces cerevisiae possesses two distinct glycyl-tRNA synthetase (GlyRS) genes: GRS1 and GRS2. GRS1 is dually functional, encoding both cytoplasmic and mitochondrial activities, while GRS2 is dysfunctional and not required for growth. The protein products of these two genes, GlyRS1 and GlyRS2, are much alike but are distinguished by an insertion peptide of GlyRS1, which is absent from GlyRS2 and other eukaryotic homologues. We show that deletion or mutation of the insertion peptide modestly impaired the enzyme's catalytic efficiency in vitro (with a 2- to 3-fold increase in Km and a 5- to 8-fold decrease in kcat). Consistently, GRS2 can be conveniently converted to a functional gene via codon optimization, and the insertion peptide is dispensable for protein stability and the rescue activity of GRS1 at 30°C in vivo. A phylogenetic analysis further showed that GRS1 and GRS2 are paralogues that arose from a gene duplication event relatively recently, with GRS1 being the predecessor. These results indicate that GlyRS2 is an active enzyme essentially resembling the insertion peptide-deleted form of GlyRS1. Our study suggests that the insertion peptide represents a novel auxiliary domain, which facilitates both productive docking and catalysis of cognate tRNAs.
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Arribere JA, Gilbert WV. Roles for transcript leaders in translation and mRNA decay revealed by transcript leader sequencing. Genome Res 2013; 23:977-87. [PMID: 23580730 PMCID: PMC3668365 DOI: 10.1101/gr.150342.112] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Transcript leaders (TLs) can have profound effects on mRNA translation and stability. To map TL boundaries genome-wide, we developed TL-sequencing (TL-seq), a technique combining enzymatic capture of m7G-capped mRNA 5′ ends with high-throughput sequencing. TL-seq identified mRNA start sites for the majority of yeast genes and revealed many examples of intragenic TL heterogeneity. Surprisingly, TL-seq identified transcription initiation sites within 6% of protein-coding regions, and these sites were concentrated near the 5′ ends of ORFs. Furthermore, ribosome density analysis showed these truncated mRNAs are translated. Translation-associated TL-seq (TATL-seq), which combines TL-seq with polysome fractionation, enabled annotation of TLs, and simultaneously assayed their function in translation. Using TATL-seq to address relationships between TL features and translation of the downstream ORF, we observed that upstream AUGs (uAUGs), and no other upstream codons, were associated with poor translation and nonsense-mediated mRNA decay (NMD). We also identified hundreds of genes with very short TLs, and demonstrated that short TLs were associated with poor translation initiation at the annotated start codon and increased initiation at downstream AUGs. This frequently resulted in out-of-frame translation and subsequent termination at premature termination codons, culminating in NMD of the transcript. Unlike previous approaches, our technique enabled observation of alternative TL variants for hundreds of genes and revealed significant differences in translation in genes with distinct TL isoforms. TL-seq and TATL-seq are useful tools for annotation and functional characterization of TLs, and can be applied to any eukaryotic system to investigate TL-mediated regulation of gene expression.
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Affiliation(s)
- Joshua A Arribere
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Wei J, Zhang Y, Ivanov IP, Sachs MS. The stringency of start codon selection in the filamentous fungus Neurospora crassa. J Biol Chem 2013; 288:9549-62. [PMID: 23396971 DOI: 10.1074/jbc.m112.447177] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In eukaryotic cells initiation may occur from near-cognate codons that differ from AUG by a single nucleotide. The stringency of start codon selection impacts the efficiency of initiation at near-cognate codons and the efficiency of initiation at AUG codons in different contexts. We used a codon-optimized firefly luciferase reporter initiated with AUG or each of the nine near-cognate codons in preferred context to examine the stringency of start codon selection in the model filamentous fungus Neurospora crassa. In vivo results indicated that the hierarchy of initiation at start codons in N. crassa (AUG ≫ CUG > GUG > ACG > AUA ≈ UUG > AUU > AUC) is similar to that in human cells. Similar results were obtained by translating mRNAs in a homologous N. crassa in vitro translation system or in rabbit reticulocyte lysate. We next examined the efficiency of initiation at AUG, CUG, and UUG codons in different contexts in vitro. The preferred context was more important for efficient initiation from near-cognate codons than from AUG. These studies demonstrated that near-cognate codons are used for initiation in N. crassa. Such events could provide additional coding capacity or have regulatory functions. Analyses of the 5'-leader regions in the N. crassa transcriptome revealed examples of highly conserved near-cognate codons in preferred contexts that could extend the N termini of the predicted polypeptides.
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Affiliation(s)
- Jiajie Wei
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, USA
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Genome-wide ribosome profiling reveals complex translational regulation in response to oxidative stress. Proc Natl Acad Sci U S A 2012; 109:17394-9. [PMID: 23045643 DOI: 10.1073/pnas.1120799109] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Information on unique and coordinated regulation of transcription and translation in response to stress is central to the understanding of cellular homeostasis. Here we used ribosome profiling coupled with next-generation sequencing to examine the interplay between transcription and translation under conditions of hydrogen peroxide treatment in Saccharomyces cerevisiae. Hydrogen peroxide treatment led to a massive and rapid increase in ribosome occupancy of short upstream ORFs, including those with non-AUG translational starts, and of the N-terminal regions of ORFs that preceded the transcriptional response. In addition, this treatment induced the synthesis of N-terminally extended proteins and elevated stop codon read-through and frameshift events. It also increased ribosome occupancy at the beginning of ORFs and potentially the duration of the elongation step. We identified proteins whose synthesis was regulated rapidly by hydrogen peroxide posttranscriptionally; however, for the majority of genes increased protein synthesis followed transcriptional regulation. These data define the landscape of genome-wide regulation of translation in response to hydrogen peroxide and suggest that potentiation (coregulation of the transcript level and translation) is a feature of oxidative stress.
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Kapeli K, Yeo GW. Genome-wide approaches to dissect the roles of RNA binding proteins in translational control: implications for neurological diseases. Front Neurosci 2012; 6:144. [PMID: 23060744 PMCID: PMC3462321 DOI: 10.3389/fnins.2012.00144] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 09/12/2012] [Indexed: 12/12/2022] Open
Abstract
Translational control of messenger RNAs (mRNAs) is a key aspect of neurobiology, defects of which can lead to neurological diseases. In response to stimuli, local translation of mRNAs is activated at synapses to facilitate long-lasting forms of synaptic plasticity, the cellular basis for learning, and memory formation. Translation, as well as all other aspects of RNA metabolism, is controlled in part by RNA binding proteins (RBPs) that directly interact with mRNAs to form mRNA-protein complexes. Disruption of RBP function is becoming widely recognized as a major cause of neurological diseases. Thus understanding the mechanisms that govern the interplay between translation control and RBP regulation in both normal and diseased neurons will provide new opportunities for novel diagnostics and therapeutic intervention. As a means of studying translational control, genome-wide methods are emerging as powerful tools that have already begun to unveil mechanisms that are missed by single-gene studies. Here, we describe the roles of RBPs in translational control, review genome-wide approaches to examine translational control, and discuss how the application of these approaches may provide mechanistic insight into the pathogenic underpinnings of RBPs in neurological diseases.
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Affiliation(s)
- Katannya Kapeli
- Department of Cellular and Molecular Medicine, University of California San Diego La Jolla, CA, USA
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Global mapping of translation initiation sites in mammalian cells at single-nucleotide resolution. Proc Natl Acad Sci U S A 2012; 109:E2424-32. [PMID: 22927429 DOI: 10.1073/pnas.1207846109] [Citation(s) in RCA: 437] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Understanding translational control in gene expression relies on precise and comprehensive determination of translation initiation sites (TIS) across the entire transcriptome. The recently developed ribosome-profiling technique enables global translation analysis, providing a wealth of information about both the position and the density of ribosomes on mRNAs. Here we present an approach, global translation initiation sequencing, applying in parallel the ribosome E-site translation inhibitors lactimidomycin and cycloheximide to achieve simultaneous detection of both initiation and elongation events on a genome-wide scale. This approach provides a view of alternative translation initiation in mammalian cells with single-nucleotide resolution. Systemic analysis of TIS positions supports the ribosome linear-scanning mechanism in TIS selection. The alternative TIS positions and the associated ORFs identified by global translation initiation sequencing are conserved between human and mouse cells, implying physiological significance of alternative translation. Our study establishes a practical platform for uncovering the hidden coding potential of the transcriptome and offers a greater understanding of the complexity of translation initiation.
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Liao CC, Lin CH, Chen SJ, Wang CC. Trans-kingdom rescue of Gln-tRNAGln synthesis in yeast cytoplasm and mitochondria. Nucleic Acids Res 2012; 40:9171-81. [PMID: 22821561 PMCID: PMC3467082 DOI: 10.1093/nar/gks689] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Aminoacylation of transfer RNAGln (tRNAGln) is performed by distinct mechanisms in different kingdoms and represents the most diverged route of aminoacyl-tRNA synthesis found in nature. In Saccharomyces cerevisiae, cytosolic Gln-tRNAGln is generated by direct glutaminylation of tRNAGln by glutaminyl-tRNA synthetase (GlnRS), whereas mitochondrial Gln-tRNAGln is formed by an indirect pathway involving charging by a non-discriminating glutamyl-tRNA synthetase and the subsequent transamidation by a specific Glu-tRNAGln amidotransferase. Previous studies showed that fusion of a yeast non-specific tRNA-binding cofactor, Arc1p, to Escherichia coli GlnRS enables the bacterial enzyme to substitute for its yeast homologue in vivo. We report herein that the same fusion enzyme, upon being imported into mitochondria, substituted the indirect pathway for Gln-tRNAGln synthesis as well, despite significant differences in the identity determinants of E. coli and yeast cytosolic and mitochondrial tRNAGln isoacceptors. Fusion of Arc1p to the bacterial enzyme significantly enhanced its aminoacylation activity towards yeast tRNAGln isoacceptors in vitro. Our study provides a mechanism by which trans-kingdom rescue of distinct pathways of Gln-tRNAGln synthesis can be conferred by a single enzyme.
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Affiliation(s)
- Chih-Chi Liao
- Department of Life Sciences, National Central University, Jung-li 32001, Taiwan, Republic of China
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Kochetov AV, Prayaga PD, Volkova OA, Sankararamakrishnan R. Hidden coding potential of eukaryotic genomes: nonAUG started ORFs. J Biomol Struct Dyn 2012; 31:103-14. [PMID: 22804099 DOI: 10.1080/07391102.2012.691367] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It is widely considered that the vast majority of eukaryotic mRNAs contain only one open reading frame (ORF) and encode single protein. However, eukaryotic ribosomes can initiate translation at alternative start codons due to leaky scanning or reinitiation mechanisms that provides an opportunity to synthesize several protein products. Recent investigations also demonstrated that alternative translation from nonAUG start codons and AUG codons in a weak nucleotide context could make an important contribution to eukaryotic proteomes. However, accurate prediction of alternative start codons demands detailed investigation of mRNA features influencing their recognition by eukaryotic ribosomes. In this work, we present the results of computational analysis of characteristics of yeast and mammalian mRNAs potentially involved in the recognition of nonAUG start codons. It was found that sequence features of nonAUG started Saccharomyces cerevisiae upstream ORFs (uORFs) were adjusted for efficient translation and these uORFs could frequently encode functional polypeptides. In particular, our initial studies revealed that predicted tertiary structures downstream of nonAUG start sites in mammalian mRNAs were energetically more stable than those predicted for AUG start sites with strong Kozak context. We hypothesize that presence of such stable tertiary structure downstream of nonAUG start sites could be an important factor for the ribosome to recognize noncanonical start codons.
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Affiliation(s)
- Alex V Kochetov
- Institute of Cytology and Genetics, 10, Lavrentiev Ave, Novosibirsk, 630090, Russia
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