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Cohen B, Golani-Armon A, Arava YS. Emerging implications for ribosomes in proximity to mitochondria. Semin Cell Dev Biol 2024; 154:123-130. [PMID: 36642616 DOI: 10.1016/j.semcdb.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 12/11/2022] [Accepted: 01/05/2023] [Indexed: 01/15/2023]
Abstract
Synthesis of all proteins in eukaryotic cells, apart from a few organellar proteins, is done by cytosolic ribosomes. Many of these ribosomes are localized in the vicinity of the functional site of their encoded protein, enabling local protein synthesis. Studies in various organisms and tissues revealed that such locally translating ribosomes are also present near mitochondria. Here, we provide a brief summary of evidence for localized translation near mitochondria, then present data suggesting that these localized ribosomes may enable local translational regulatory processes in response to mitochondria needs. Finally, we describe the involvement of such localized ribosomes in the quality control of protein synthesis and mitochondria. These emerging views suggest that ribosomes localized near mitochondria are a hub for a variety of activities with diverse implications on mitochondria physiology.
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Affiliation(s)
- Bar Cohen
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Adi Golani-Armon
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yoav S Arava
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
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2
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Dulic M, Godinic-Mikulcic V, Kekez M, Evic V, Rokov-Plavec J. Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease. Life (Basel) 2024; 14:124. [PMID: 38255739 PMCID: PMC10817482 DOI: 10.3390/life14010124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Seryl-tRNA synthetases (SerRSs), members of the aminoacyl-tRNA synthetase family, interact with diverse proteins, enabling SerRSs to enhance their role in the translation of the genetic message or to perform alternative functions in cellular processes beyond translation. Atypical archaeal SerRS interacts with arginyl-tRNA synthetase and proteins of the ribosomal P-stalk to optimize translation through tRNA channeling. The complex between yeast SerRS and peroxin Pex21p provides a connection between translation and peroxisome function. The partnership between Arabidopsis SerRS and BEN1 indicates a link between translation and brassinosteroid metabolism and may be relevant in plant stress response mechanisms. In Drosophila, the unusual heterodimeric mitochondrial SerRS coordinates mitochondrial translation and replication via interaction with LON protease. Evolutionarily conserved interactions of yeast and human SerRSs with m3C32 tRNA methyltransferases indicate coordination between tRNA modification and aminoacylation in the cytosol and mitochondria. Human cytosolic SerRS is a cellular hub protein connecting translation to vascular development, angiogenesis, lipogenesis, and telomere maintenance. When translocated to the nucleus, SerRS acts as a master negative regulator of VEGFA gene expression. SerRS alone or in complex with YY1 and SIRT2 competes with activating transcription factors NFκB1 and c-Myc, resulting in balanced VEGFA expression important for proper vascular development and angiogenesis. In hypoxia, SerRS phosphorylation diminishes its binding to the VEGFA promoter, while the lack of nutrients triggers SerRS glycosylation, reducing its nuclear localization. Additionally, SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and cellular senescence. As an antitumor and antiangiogenic factor, human cytosolic SerRS appears to be a promising drug target and therapeutic agent for treating cancer, cardiovascular diseases, and possibly obesity and aging.
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Affiliation(s)
| | | | | | | | - Jasmina Rokov-Plavec
- Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia; (M.D.); (V.G.-M.); (M.K.); (V.E.)
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3
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López-Soldado I, Torres AG, Ventura R, Martínez-Ruiz I, Díaz-Ramos A, Planet E, Cooper D, Pazderska A, Wanic K, O'Hanlon D, O'Gorman DJ, Carbonell T, de Pouplana LR, Nolan JJ, Zorzano A, Hernández-Alvarez MI. Decreased expression of mitochondrial aminoacyl-tRNA synthetases causes downregulation of OXPHOS subunits in type 2 diabetic muscle. Redox Biol 2023; 61:102630. [PMID: 36796135 PMCID: PMC9958393 DOI: 10.1016/j.redox.2023.102630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/26/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
Type 2 diabetes mellitus (T2D) affects millions of people worldwide and is one of the leading causes of morbidity and mortality. The skeletal muscle (SKM) is one of the most important tissues involved in maintaining glucose homeostasis and substrate oxidation, and it undergoes insulin resistance in T2D. In this study, we identify the existence of alterations in the expression of mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) in skeletal muscle from two different forms of T2D: early-onset type 2 diabetes (YT2) (onset of the disease before 30 years of age) and the classical form of the disease (OT2). GSEA analysis from microarray studies revealed the repression of mitochondrial mt-aaRSs independently of age, which was validated by real-time PCR assays. In agreement with this, a reduced expression of several encoding mt-aaRSs was also detected in skeletal muscle from diabetic (db/db) mice but not in obese ob/ob mice. In addition, the expression of the mt-aaRSs proteins most relevant in the synthesis of mitochondrial proteins, threonyl-tRNA, and leucyl-tRNA synthetases (TARS2 and LARS2) were also repressed in muscle from db/db mice. It is likely that these alterations participate in the reduced expression of proteins synthesized in the mitochondria detected in db/db mice. We also document an increased iNOS abundance in mitochondrial-enriched muscle fractions from diabetic mice that may inhibit aminoacylation of TARS2 and LARS2 by nitrosative stress. Our results indicate a reduced expression of mt-aaRSs in skeletal muscle from T2D patients, which may participate in the reduced expression of proteins synthesized in mitochondria. An enhanced mitochondrial iNOS could play a regulatory role in diabetes.
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Affiliation(s)
- Iliana López-Soldado
- Department de Bioquímica i Biomedicina Molecular, Facultat de Biología, 08028, Spain; Institut de Biomedicina de la Universitat de Barcelona IBUB, Barcelona, Spain
| | - Adrian Gabriel Torres
- Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Raúl Ventura
- Department de Bioquímica i Biomedicina Molecular, Facultat de Biología, 08028, Spain; Institut de Biomedicina de la Universitat de Barcelona IBUB, Barcelona, Spain
| | - Inma Martínez-Ruiz
- Department de Bioquímica i Biomedicina Molecular, Facultat de Biología, 08028, Spain; Institut de Biomedicina de la Universitat de Barcelona IBUB, Barcelona, Spain
| | - Angels Díaz-Ramos
- Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Spain
| | - Evarist Planet
- Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Diane Cooper
- National Institute for Cellular Biotechnology, 3U Diabetes Partnership & School of Health and Human Performance, Dublin City University, Dublin, Ireland
| | - Agnieszka Pazderska
- Metabolic Research Unit, St James's Hospital, and Trinity College, Dublin, Ireland
| | - Krzysztof Wanic
- Metabolic Research Unit, St James's Hospital, and Trinity College, Dublin, Ireland
| | - Declan O'Hanlon
- Metabolic Research Unit, St James's Hospital, and Trinity College, Dublin, Ireland
| | - Donal J O'Gorman
- National Institute for Cellular Biotechnology, 3U Diabetes Partnership & School of Health and Human Performance, Dublin City University, Dublin, Ireland
| | - Teresa Carbonell
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, 08028, Barcelona, Spain
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, Barcelona, Spain
| | - John J Nolan
- Metabolic Research Unit, St James's Hospital, and Trinity College, Dublin, Ireland
| | - Antonio Zorzano
- Department de Bioquímica i Biomedicina Molecular, Facultat de Biología, 08028, Spain; Institute for Research in Biomedicine (IRB Barcelona), the Barcelona Institute of Science and Technology, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Spain.
| | - María Isabel Hernández-Alvarez
- Department de Bioquímica i Biomedicina Molecular, Facultat de Biología, 08028, Spain; Institut de Biomedicina de la Universitat de Barcelona IBUB, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Spain.
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Chrzanowska-Lightowlers ZM, Lightowlers RN. Translation in Mitochondrial Ribosomes. Methods Mol Biol 2023; 2661:53-72. [PMID: 37166631 DOI: 10.1007/978-1-0716-3171-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Mitochondrial protein synthesis is essential for the life of aerobic eukaryotes. Without it, oxidative phosphorylation cannot be coupled. Evolution has shaped a battery of factors and machinery that are key to production of just a handful of critical proteins. In this general concept chapter, we attempt to briefly summarize our current knowledge of the overall process in mitochondria from a variety of species, breaking this down to the four parts of translation: initiation, elongation, termination, and recycling. Where appropriate, we highlight differences between species and emphasize gaps in our understanding. Excitingly, with the current revolution in cryoelectron microscopy and mitochondrial genome editing, it is highly likely that many of these gaps will be resolved in the near future. However, the absence of a faithful in vitro reconstituted system to study mitochondrial translation is still problematic.
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Affiliation(s)
- Zofia M Chrzanowska-Lightowlers
- Wellcome Centre for Mitochondrial Research, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne, UK.
| | - Robert N Lightowlers
- Wellcome Centre for Mitochondrial Research, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne, UK
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Peng GX, Mao XL, Cao Y, Yao SY, Li QR, Chen X, Wang ED, Zhou XL. RNA granule-clustered mitochondrial aminoacyl-tRNA synthetases form multiple complexes with the potential to fine-tune tRNA aminoacylation. Nucleic Acids Res 2022; 50:12951-12968. [PMID: 36503967 PMCID: PMC9825176 DOI: 10.1093/nar/gkac1141] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/23/2022] [Accepted: 11/15/2022] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial RNA metabolism is suggested to occur in identified compartmentalized foci, i.e. mitochondrial RNA granules (MRGs). Mitochondrial aminoacyl-tRNA synthetases (mito aaRSs) catalyze tRNA charging and are key components in mitochondrial gene expression. Mutations of mito aaRSs are associated with various human disorders. However, the suborganelle distribution, interaction network and regulatory mechanism of mito aaRSs remain largely unknown. Here, we found that all mito aaRSs partly colocalize with MRG, and this colocalization is likely facilitated by tRNA-binding capacity. A fraction of human mitochondrial AlaRS (hmtAlaRS) and hmtSerRS formed a direct complex via interaction between catalytic domains in vivo. Aminoacylation activities of both hmtAlaRS and hmtSerRS were fine-tuned upon complex formation in vitro. We further established a full spectrum of interaction networks via immunoprecipitation and mass spectrometry for all mito aaRSs and discovered interactions between hmtSerRS and hmtAsnRS, between hmtSerRS and hmtTyrRS and between hmtThrRS and hmtArgRS. The activity of hmtTyrRS was also influenced by the presence of hmtSerRS. Notably, hmtSerRS utilized the same catalytic domain in mediating several interactions. Altogether, our results systematically analyzed the suborganelle localization and interaction network of mito aaRSs and discovered several mito aaRS-containing complexes, deepening our understanding of the functional and regulatory mechanisms of mito aaRSs.
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Affiliation(s)
| | | | - Yating Cao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Shi-Ying Yao
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Qing-Run Li
- CAS Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Xin Chen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - En-Duo Wang
- Correspondence may also be addressed to En-Duo Wang. Tel: +86 21 5492 1241; Fax: +86 21 5492 1011;
| | - Xiao-Long Zhou
- To whom correspondence should be addressed. Tel: +86 21 5492 1247; Fax: +86 21 5492 1011;
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Willems P, Ndah E, Jonckheere V, Van Breusegem F, Van Damme P. To New Beginnings: Riboproteogenomics Discovery of N-Terminal Proteoforms in Arabidopsis Thaliana. Front Plant Sci 2022; 12:778804. [PMID: 35069635 PMCID: PMC8770321 DOI: 10.3389/fpls.2021.778804] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/18/2021] [Indexed: 06/14/2023]
Abstract
Alternative translation initiation is a widespread event in biology that can shape multiple protein forms or proteoforms from a single gene. However, the respective contribution of alternative translation to protein complexity remains largely enigmatic. By complementary ribosome profiling and N-terminal proteomics (i.e., riboproteogenomics), we provide clear-cut evidence for ~90 N-terminal proteoform pairs shaped by (alternative) translation initiation in Arabidopsis thaliana. Next to several cases additionally confirmed by directed mutagenesis, identified alternative protein N-termini follow the enzymatic rules of co-translational N-terminal protein acetylation and initiator methionine removal. In contrast to other eukaryotic models, N-terminal acetylation in plants cannot generally be considered as a proxy of translation initiation because of its posttranslational occurrence on mature proteolytic neo-termini (N-termini) localized in the chloroplast stroma. Quantification of N-terminal acetylation revealed differing co- vs. posttranslational N-terminal acetylation patterns. Intriguingly, our data additionally hints to alternative translation initiation serving as a common mechanism to supply protein copies in multiple cellular compartments, as alternative translation sites are often in close proximity to cleavage sites of N-terminal transit sequences of nuclear-encoded chloroplastic and mitochondrial proteins. Overall, riboproteogenomics screening enables the identification of (differential localized) N-terminal proteoforms raised upon alternative translation.
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Affiliation(s)
- Patrick Willems
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- Vlaams Instituut voor Biotechnologie (VIB)-Center for Plant Systems Biology, Ghent, Belgium
| | - Elvis Ndah
- integrative Riboproteogenomics, Interactomics and Proteomics Unit, Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Veronique Jonckheere
- integrative Riboproteogenomics, Interactomics and Proteomics Unit, Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Frank Van Breusegem
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- Vlaams Instituut voor Biotechnologie (VIB)-Center for Plant Systems Biology, Ghent, Belgium
| | - Petra Van Damme
- integrative Riboproteogenomics, Interactomics and Proteomics Unit, Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
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Chakraborti S, Chhibber-Goel J, Sharma A. Drug targeting of aminoacyl-tRNA synthetases in Anopheles species and Aedes aegypti that cause malaria and dengue. Parasit Vectors 2021; 14:605. [PMID: 34895309 PMCID: PMC8665550 DOI: 10.1186/s13071-021-05106-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 11/19/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Mosquito-borne diseases have a devastating impact on human civilization. A few species of Anopheles mosquitoes are responsible for malaria transmission, and while there has been a reduction in malaria-related deaths worldwide, growing insecticide resistance is a cause for concern. Aedes mosquitoes are known vectors of viral infections, including dengue, yellow fever, chikungunya, and Zika. Aminoacyl-tRNA synthetases (aaRSs) are key players in protein synthesis and are potent anti-infective drug targets. The structure-function activity relationship of aaRSs in mosquitoes (in particular, Anopheles and Aedes spp.) remains unexplored. METHODS We employed computational techniques to identify aaRSs from five different mosquito species (Anopheles culicifacies, Anopheles stephensi, Anopheles gambiae, Anopheles minimus, and Aedes aegypti). The VectorBase database ( https://vectorbase.org/vectorbase/app ) and web-based tools were utilized to predict the subcellular localizations (TargetP-2.0, UniProt, DeepLoc-1.0), physicochemical characteristics (ProtParam), and domain arrangements (PfAM, InterPro) of the aaRSs. Structural models for prolyl (PRS)-, and phenylalanyl (FRS)-tRNA synthetases-were generated using the I-TASSER and Phyre protein modeling servers. RESULTS Among the vector species, a total of 37 (An. gambiae), 37 (An. culicifacies), 37 (An. stephensi), 37 (An. minimus), and 35 (Ae. aegypti) different aaRSs were characterized within their respective mosquito genomes. Sequence identity amongst the aaRSs from the four Anopheles spp. was > 80% and in Ae. aegypti was > 50%. CONCLUSIONS Structural analysis of two important aminoacyl-tRNA synthetases [prolyl (PRS) and phenylanalyl (FRS)] of Anopheles spp. suggests structural and sequence similarity with potential antimalarial inhibitor [halofuginone (HF) and bicyclic azetidine (BRD1369)] binding sites. This suggests the potential for repurposing of these inhibitors against the studied Anopheles spp. and Ae. aegypti.
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Affiliation(s)
| | - Jyoti Chhibber-Goel
- Molecular Medicine, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Amit Sharma
- Molecular Medicine Group, National Institute of Malaria Research, New Delhi, India
- Molecular Medicine, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Garin S, Levi O, Forrest ME, Antonellis A, Arava YS. Comprehensive characterization of mRNAs associated with yeast cytosolic aminoacyl-tRNA synthetases. RNA Biol 2021; 18:2605-2616. [PMID: 34039240 PMCID: PMC8632134 DOI: 10.1080/15476286.2021.1935116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/18/2021] [Accepted: 05/21/2021] [Indexed: 12/27/2022] Open
Abstract
Aminoacyl-tRNA synthetases (aaRSs) are a conserved family of enzymes with an essential role in protein synthesis: ligating amino acids to cognate tRNA molecules for translation. In addition to their role in tRNA charging, aaRSs have acquired non-canonical functions, including post-transcriptional regulation of mRNA expression. Yet, the extent and mechanisms of these post-transcriptional functions are largely unknown. Herein, we performed a comprehensive transcriptome analysis to define the mRNAs that are associated with almost all aaRSs present in S. cerevisiae cytosol. Nineteen (out of twenty) isogenic strains of GFP-tagged cytosolic aaRSs were subjected to immunoprecipitation with anti-GFP beads along with an untagged control. mRNAs associated with each aaRS were then identified by RNA-seq. The extent of mRNA association varied significantly between aaRSs, from MetRS in which none appeared to be statistically significant, to PheRS that binds hundreds of different mRNAs. Interestingly, many target mRNAs are bound by multiple aaRSs, suggesting co-regulation by this family of enzymes. Gene Ontology analyses for aaRSs with a considerable number of target mRNAs discovered an enrichment for pathways of amino acid metabolism and of ribosome biosynthesis. Furthermore, sequence and structure motif analysis revealed for some aaRSs an enrichment for motifs that resemble the anticodon stem loop of cognate tRNAs. These data suggest that aaRSs coordinate mRNA expression in response to amino acid availability and may utilize RNA elements that mimic their canonical tRNA binding partners.
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Affiliation(s)
- Shahar Garin
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Ofri Levi
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Megan E. Forrest
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Yoav S. Arava
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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Capriglia F, Rizzo F, Petrosillo G, Morea V, d'Amati G, Cantatore P, Roberti M, Loguercio Polosa P, Bruni F. Exploring the Ability of LARS2 Carboxy-Terminal Domain in Rescuing the MELAS Phenotype. Life (Basel) 2021; 11:674. [PMID: 34357047 DOI: 10.3390/life11070674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 12/25/2022] Open
Abstract
The m.3243A>G mutation within the mitochondrial mt-tRNALeu(UUR) gene is the most prevalent variant linked to mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome. This pathogenic mutation causes severe impairment of mitochondrial protein synthesis due to alterations of the mutated tRNA, such as reduced aminoacylation and a lack of post-transcriptional modification. In transmitochondrial cybrids, overexpression of human mitochondrial leucyl-tRNA synthetase (LARS2) has proven effective in rescuing the phenotype associated with m.3243A>G substitution. The rescuing activity resides in the carboxy-terminal domain (Cterm) of the enzyme; however, the precise molecular mechanisms underlying this process have not been fully elucidated. To deepen our knowledge on the rescuing mechanisms, we demonstrated the interactions of the Cterm with mutated mt-tRNALeu(UUR) and its precursor in MELAS cybrids. Further, the effect of Cterm expression on mitochondrial functions was evaluated. We found that Cterm ameliorates de novo mitochondrial protein synthesis, whilst it has no effect on mt-tRNALeu(UUR) steady-state levels and aminoacylation. Despite the complete recovery of cell viability and the increase in mitochondrial translation, Cterm-overexpressing cybrids were not able to recover bioenergetic competence. These data suggest that, in our MELAS cell model, the beneficial effect of Cterm may be mediated by factors that are independent of the mitochondrial bioenergetics.
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Soukal P, Hrdá Š, Karnkowska A, Milanowski R, Szabová J, Hradilová M, Strnad H, Vlček Č, Čepička I, Hampl V. Heterotrophic euglenid Rhabdomonas costata resembles its phototrophic relatives in many aspects of molecular and cell biology. Sci Rep 2021; 11:13070. [PMID: 34158556 DOI: 10.1038/s41598-021-92174-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 05/28/2021] [Indexed: 02/05/2023] Open
Abstract
Euglenids represent a group of protists with diverse modes of feeding. To date, only a partial genomic sequence of Euglena gracilis and transcriptomes of several phototrophic and secondarily osmotrophic species are available, while primarily heterotrophic euglenids are seriously undersampled. In this work, we begin to fill this gap by presenting genomic and transcriptomic drafts of a primary osmotroph, Rhabdomonas costata. The current genomic assembly length of 100 Mbp is 14× smaller than that of E. gracilis. Despite being too fragmented for comprehensive gene prediction it provided fragments of the mitochondrial genome and comparison of the transcriptomic and genomic data revealed features of its introns, including several candidates for nonconventional types. A set of 39,456 putative R. costata proteins was predicted from the transcriptome. Annotation of the mitochondrial core metabolism provides the first data on the facultatively anaerobic mitochondrion of R. costata, which in most respects resembles the mitochondrion of E. gracilis with a certain level of streamlining. R. costata can synthetise thiamine by enzymes of heterogenous provenances and haem by a mitochondrial-cytoplasmic C4 pathway with enzymes orthologous to those found in E. gracilis. The low percentage of green algae-affiliated genes supports the ancestrally osmotrophic status of this species.
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Levi O, Arava YS. RNA modifications as a common denominator between tRNA and mRNA. Curr Genet 2021; 67:545-551. [PMID: 33683402 DOI: 10.1007/s00294-021-01168-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 12/27/2022]
Abstract
Recent studies underscore RNA modifications as a novel mechanism to coordinate expression and function of different genes. While modifications on the sugar or base moieties of tRNA are well known, their roles in mRNA regulation are only starting to emerge. Interestingly, some modifications are present in both tRNA and mRNA, and here we discuss the functional significance of these common features. We describe key modifications that are present in both RNA types, elaborate on proteins that interact with them, and indicate recent works that identify roles in communicating tRNA processes and mRNA regulation. We propose that as tools are developed, the shortlist of features that are common between types of RNA will greatly expand and proteins that interact with them will be identified. In conclusion, the presence of the same modification in both RNA types provides an intersect between tRNA processes and mRNA regulation and implies a novel mechanism for connecting diverse cellular processes.
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Affiliation(s)
- Ofri Levi
- Faculty of Biology, Technion-Israel Institute of Technology, 3200003, Haifa, Israel
| | - Yoav S Arava
- Faculty of Biology, Technion-Israel Institute of Technology, 3200003, Haifa, Israel.
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