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Impact of tRNA Modifications and tRNA-Modifying Enzymes on Proteostasis and Human Disease. Int J Mol Sci 2018; 19:ijms19123738. [PMID: 30477220 PMCID: PMC6321623 DOI: 10.3390/ijms19123738] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 11/17/2018] [Accepted: 11/20/2018] [Indexed: 12/14/2022] Open
Abstract
Transfer RNAs (tRNAs) are key players of protein synthesis, as they decode the genetic information organized in mRNA codons, translating them into the code of 20 amino acids. To be fully active, tRNAs undergo extensive post-transcriptional modifications, catalyzed by different tRNA-modifying enzymes. Lack of these modifications increases the level of missense errors and affects codon decoding rate, contributing to protein aggregation with deleterious consequences to the cell. Recent works show that tRNA hypomodification and tRNA-modifying-enzyme deregulation occur in several diseases where proteostasis is affected, namely, neurodegenerative and metabolic diseases. In this review, we discuss the recent findings that correlate aberrant tRNA modification with proteostasis imbalances, in particular in neurological and metabolic disorders, and highlight the association between tRNAs, their modifying enzymes, translational decoding, and disease onset.
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Zhang Q, Zhang L, Chen D, He X, Yao S, Zhang Z, Chen Y, Guan MX. Deletion of Mtu1 (Trmu) in zebrafish revealed the essential role of tRNA modification in mitochondrial biogenesis and hearing function. Nucleic Acids Res 2018; 46:10930-10945. [PMID: 30137487 PMCID: PMC6237746 DOI: 10.1093/nar/gky758] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/07/2018] [Accepted: 08/10/2018] [Indexed: 11/14/2022] Open
Abstract
Mtu1(Trmu) is a highly conserved tRNA modifying enzyme responsible for the biosynthesis of τm5s2U at the wobble position of tRNAGln, tRNAGlu and tRNALys. Our previous investigations showed that MTU1 mutation modulated the phenotypic manifestation of deafness-associated mitochondrial 12S rRNA mutation. However, the pathophysiology of MTU1 deficiency remains poorly understood. Using the mtu1 knock-out zebrafish generated by CRISPR/Cas9 system, we demonstrated the abolished 2-thiouridine modification of U34 of mitochondrial tRNALys, tRNAGlu and tRNAGln in the mtu1 knock-out zebrafish. The elimination of this post-transcriptional modification mediated mitochondrial tRNA metabolisms, causing the global decreases in the levels of mitochondrial tRNAs. The aberrant mitochondrial tRNA metabolisms led to the impairment of mitochondrial translation, respiratory deficiencies and reductions of mitochondrial ATP production. These mitochondria dysfunctions caused the defects in hearing organs. Strikingly, mtu1-/- mutant zebrafish displayed the abnormal startle response and swimming behaviors, significant decreases in the sizes of saccular otolith and numbers of hair cells in the auditory and vestibular organs. Furthermore, mtu1-/- mutant zebrafish exhibited the significant reductions in the hair bundle densities in utricle, saccule and lagena. Therefore, our findings may provide new insights into the pathophysiology of deafness, which was manifested by the deficient modifications at wobble position of mitochondrial tRNAs.
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Affiliation(s)
- Qinghai Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Luwen Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Danni Chen
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Xiao He
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Shihao Yao
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zengming Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Ye Chen
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Joint Institute of Genetics and Genome Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China
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Cosentino C, Toivonen S, Diaz Villamil E, Atta M, Ravanat JL, Demine S, Schiavo A, Pachera N, Deglasse JP, Jonas JC, Balboa D, Otonkoski T, Pearson ER, Marchetti P, Eizirik DL, Cnop M, Igoillo-Esteve M. Pancreatic β-cell tRNA hypomethylation and fragmentation link TRMT10A deficiency with diabetes. Nucleic Acids Res 2018; 46:10302-10318. [PMID: 30247717 PMCID: PMC6212784 DOI: 10.1093/nar/gky839] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/17/2018] [Accepted: 09/10/2018] [Indexed: 12/20/2022] Open
Abstract
Transfer RNAs (tRNAs) are non-coding RNA molecules essential for protein synthesis. Post-transcriptionally they are heavily modified to improve their function, folding and stability. Intronic polymorphisms in CDKAL1, a tRNA methylthiotransferase, are associated with increased type 2 diabetes risk. Loss-of-function mutations in TRMT10A, a tRNA methyltransferase, are a monogenic cause of early onset diabetes and microcephaly. Here we confirm the role of TRMT10A as a guanosine 9 tRNA methyltransferase, and identify tRNAGln and tRNAiMeth as two of its targets. Using RNA interference and induced pluripotent stem cell-derived pancreatic β-like cells from healthy controls and TRMT10A-deficient patients we demonstrate that TRMT10A deficiency induces oxidative stress and triggers the intrinsic pathway of apoptosis in β-cells. We show that tRNA guanosine 9 hypomethylation leads to tRNAGln fragmentation and that 5'-tRNAGln fragments mediate TRMT10A deficiency-induced β-cell death. This study unmasks tRNA hypomethylation and fragmentation as a hitherto unknown mechanism of pancreatic β-cell demise relevant to monogenic and polygenic forms of diabetes.
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Affiliation(s)
- Cristina Cosentino
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Sanna Toivonen
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Esteban Diaz Villamil
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Mohamed Atta
- CEA/Grenoble, DRF/BIG/LCBM UMR5249, Grenoble, France
| | - Jean-Luc Ravanat
- Université Grenoble Alpes, CEA, CNRS INAC, SyMMES UMR 5819, Grenoble, France
| | - Stéphane Demine
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Andrea Alex Schiavo
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Nathalie Pachera
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Jean-Philippe Deglasse
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d’ Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Jean-Christophe Jonas
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d’ Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Diego Balboa
- Research Programs Unit, Molecular Neurology and Biomedicum Stem Cell Centre, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Timo Otonkoski
- Research Programs Unit, Molecular Neurology and Biomedicum Stem Cell Centre, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Ewan R Pearson
- Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, UK
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Décio L Eizirik
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles, 1070 Brussels, Belgium
- Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium
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54
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Kumbhar NM, Gopal JS. Structural significance of hypermodified nucleoside 5-carboxymethylaminomethyluridine (cmnm 5U) from 'wobble' (34th) position of mitochondrial tRNAs: Molecular modeling and Markov state model studies. J Mol Graph Model 2018; 86:66-83. [PMID: 30336453 DOI: 10.1016/j.jmgm.2018.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 10/02/2018] [Accepted: 10/04/2018] [Indexed: 11/28/2022]
Abstract
A quantum chemical semi-empirical RM1 approach was used to deduce the structural role of hypermodified nucleoside 5-carboxymethylaminomethyluridine 5'-monophosphate (pcmnm5U) from 'wobble' (34th) position of mitochondrial tRNAs. The energetically preferred pcmnm5U(34) adopted a 'skew' conformation for C5-substituted side chain (-CH2-NH2+-CH2-COO-) moiety that orient towards the 5'-ribose-phosphate backbone, which support 'anti' orientation of glycosyl (χ34) torsion angle. Preferred conformation of pcmnm5U(34) was stabilized by O(4) … HC(10), O1P⋯HN(11), O(15) … HN(11), O(15) … HC(10), O4' … HC(6) and O(2) … HC2' hydrogen bonding interactions. The high flexibility of side chain moiety displayed different structural properties for pcmnm5U(34). Three different conformations of pcmnm5U(34) were observed in molecular dynamics simulations and Markov state model studies. The unmodified uracil revealed 'syn' and 'anti' orientations for glycosyl (χ34) torsion angle that substantiate the role of "-CH2-NH2+-CH2-COO-" moiety in maintaining the 'anti' orientation of pcmnm5U(34). The preferred conformation of pcmnm5U(34) helps to recognize Guanosine more proficiently than Adenosine from the third position of codons. The role of pcmnm5U(34) in tRNA biogenesis paves the way to understand its structural significance in usual mitochondrial metabolism and respiration.
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Affiliation(s)
- Navanath M Kumbhar
- Garware Research Centre, Department of Chemistry, Savitribai Phule Pune University (Formerly University of Pune), Pune, 411007, India.
| | - Janhavi S Gopal
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University (Formerly University of Pune), Pune, 411007, India
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55
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Chambers AE, Richardson AE, Read DF, Waller TJ, Bernstein DA, Smaldino PJ. An In Vitro Assay to Detect tRNA-Isopentenyl Transferase Activity. J Vis Exp 2018. [PMID: 30346392 DOI: 10.3791/58100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
N6-isopentenyladenosine RNA modifications are functionally diverse and highly conserved among prokaryotes and eukaryotes. One of the most highly conserved N6-isopentenyladenosine modifications occurs at the A37 position in a subset of tRNAs. This modification improves translation efficiency and fidelity by increasing the affinity of the tRNA for the ribosome. Mutation of enzymes responsible for this modification in eukaryotes are associated with several disease states, including mitochondrial dysfunction and cancer. Therefore, understanding the substrate specificity and biochemical activities of these enzymes is important for understanding of normal and pathologic eukaryotic biology. A diverse array of methods has been employed to characterize i6A modifications. Herein is described a direct approach for the detection of isopentenylation by Mod5. This method utilizes incubation of RNAs with a recombinant isopentenyl transferase, followed by RNase T1 digestion, and 1-dimensional gel electrophoresis analysis to detect i6A modifications. In addition, the potential adaptability of this protocol to characterize other RNA-modifying enzymes is discussed.
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Affiliation(s)
| | | | - David F Read
- Department of Genome Sciences, University of Washington
| | - Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan
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Mitochondrial DNA transcription and translation: clinical syndromes. Essays Biochem 2018; 62:321-340. [PMID: 29980628 PMCID: PMC6056718 DOI: 10.1042/ebc20170103] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 01/15/2023]
Abstract
Diagnosing primary mitochondrial diseases is challenging in clinical practice. Although, defective oxidative phosphorylation (OXPHOS) is the common final pathway, it is unknown why different mtDNA or nuclear mutations result in largely heterogeneous and often tissue -specific clinical presentations. Mitochondrial tRNA (mt-tRNA) mutations are frequent causes of mitochondrial diseases both in children and adults. However numerous nuclear mutations involved in mitochondrial protein synthesis affecting ubiquitously expressed genes have been reported in association with very tissue specific clinical manifestations suggesting that there are so far unknown factors determining the tissue specificity in mitochondrial translation. Most of these gene defects result in histological abnormalities and multiple respiratory chain defects in the affected organs. The clinical phenotypes are usually early-onset, severe, and often fatal, implying the importance of mitochondrial translation from birth. However, some rare, reversible infantile mitochondrial diseases are caused by very specific defects of mitochondrial translation. An unbiased genetic approach (whole exome sequencing, RNA sequencing) combined with proteomics and functional studies revealed novel factors involved in mitochondrial translation which contribute to the clinical manifestation and recovery in these rare reversible mitochondrial conditions.
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57
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Mitochondrial transcription and translation: overview. Essays Biochem 2018; 62:309-320. [PMID: 30030363 PMCID: PMC6056719 DOI: 10.1042/ebc20170102] [Citation(s) in RCA: 165] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 12/13/2022]
Abstract
Mitochondria are the major source of ATP in the cell. Five multi-subunit complexes in the inner membrane of the organelle are involved in the oxidative phosphorylation required for ATP production. Thirteen subunits of these complexes are encoded by the mitochondrial genome often referred to as mtDNA. For this reason, the expression of mtDNA is vital for the assembly and functioning of the oxidative phosphorylation complexes. Defects of the mechanisms regulating mtDNA gene expression have been associated with deficiencies in assembly of these complexes, resulting in mitochondrial diseases. Recently, numerous factors involved in these processes have been identified and characterized leading to a deeper understanding of the mechanisms that underlie mitochondrial diseases.
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58
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Koh CS, Sarin LP. Transfer RNA modification and infection – Implications for pathogenicity and host responses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:419-432. [DOI: 10.1016/j.bbagrm.2018.01.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/04/2018] [Accepted: 01/19/2018] [Indexed: 12/19/2022]
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59
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Arimbasseri GA. Interactions between RNAP III transcription machinery and tRNA processing factors. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:354-360. [PMID: 29428193 DOI: 10.1016/j.bbagrm.2018.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 02/06/2018] [Accepted: 02/06/2018] [Indexed: 10/18/2022]
Abstract
Eukaryotes have at least three nuclear RNA polymerases to carry out transcription. While RNA polymerases I and II are responsible for ribosomal RNA transcription and messenger RNA transcription, respectively, RNA Polymerase III transcribes approximately up to 300 nt long noncoding RNAs, including tRNA. For all three RNAPs, the nascent transcripts generated undergo extensive post-transcriptional processing. Transcription of mRNAs by RNAP II and their processing are coupled with the aid of the C-terminal domain of the RNAP II. RNAP I transcription and the processing of its transcripts are co-localized to the nucleolus and to some extent, rRNA processing occurs co-transcriptionally. Here, I review the current evidence for the interaction between tRNA processing factors and RNA polymerase III. These interactions include the moonlighting functions of tRNA processing factors in RNAP III transcription and the indirect effect of tRNA transcription levels on tRNA modification machinery.
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Affiliation(s)
- G Aneeshkumar Arimbasseri
- Molecular Genetics Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
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60
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Chen X, Wang F, Maerhaba A, Li Q, Wang J, Liu X, Zheng J, Chen Y, Guo Y. Novel mitochondrial gene variants in Northwestern Chinese probands with non-syndromic hearing loss by whole mitochondrial genome screening. Gene 2018; 652:59-65. [DOI: 10.1016/j.gene.2018.01.098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/16/2018] [Accepted: 01/29/2018] [Indexed: 11/28/2022]
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A tRNA's fate is decided at its 3' end: Collaborative actions of CCA-adding enzyme and RNases involved in tRNA processing and degradation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:433-441. [PMID: 29374586 DOI: 10.1016/j.bbagrm.2018.01.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/15/2018] [Accepted: 01/19/2018] [Indexed: 02/07/2023]
Abstract
tRNAs are key players in translation and are additionally involved in a wide range of distinct cellular processes. The vital importance of tRNAs becomes evident in numerous diseases that are linked to defective tRNA molecules. It is therefore not surprising that the structural intactness of tRNAs is continuously scrutinized and defective tRNAs are eliminated. In this process, erroneous tRNAs are tagged with single-stranded RNA sequences that are recognized by degrading exonucleases. Recent discoveries have revealed that the CCA-adding enzyme - actually responsible for the de novo synthesis of the 3'-CCA end - plays an indispensable role in tRNA quality control by incorporating a second CCA triplet that is recognized as a degradation tag. In this review, we give an update on the latest findings regarding tRNA quality control that turns out to represent an interplay of the CCA-adding enzyme and RNases involved in tRNA degradation and maturation. In particular, the RNase-induced turnover of the CCA end is now recognized as a trigger for the CCA-adding enzyme to repeatedly scrutinize the structural intactness of a tRNA. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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O'Byrne JJ, Tarailo-Graovac M, Ghani A, Champion M, Deshpande C, Dursun A, Ozgul RK, Freisinger P, Garber I, Haack TB, Horvath R, Barić I, Husain RA, Kluijtmans LAJ, Kotzaeridou U, Morris AA, Ross CJ, Santra S, Smeitink J, Tarnopolsky M, Wortmann SB, Mayr JA, Brunner-Krainz M, Prokisch H, Wasserman WW, Wevers RA, Engelke UF, Rodenburg RJ, Ting TW, McFarland R, Taylor RW, Salvarinova R, van Karnebeek CDM. The genotypic and phenotypic spectrum of MTO1 deficiency. Mol Genet Metab 2018; 123:28-42. [PMID: 29331171 PMCID: PMC5780301 DOI: 10.1016/j.ymgme.2017.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/11/2017] [Accepted: 11/11/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND Mitochondrial diseases, a group of multi-systemic disorders often characterized by tissue-specific phenotypes, are usually progressive and fatal disorders resulting from defects in oxidative phosphorylation. MTO1 (Mitochondrial tRNA Translation Optimization 1), an evolutionarily conserved protein expressed in high-energy demand tissues has been linked to human early-onset combined oxidative phosphorylation deficiency associated with hypertrophic cardiomyopathy, often referred to as combined oxidative phosphorylation deficiency-10 (COXPD10). MATERIAL AND METHODS Thirty five cases of MTO1 deficiency were identified and reviewed through international collaboration. The cases of two female siblings, who presented at 1 and 2years of life with seizures, global developmental delay, hypotonia, elevated lactate and complex I and IV deficiency on muscle biopsy but without cardiomyopathy, are presented in detail. RESULTS For the description of phenotypic features, the denominator varies as the literature was insufficient to allow for complete ascertainment of all data for the 35 cases. An extensive review of all known MTO1 deficiency cases revealed the most common features at presentation to be lactic acidosis (LA) (21/34; 62% cases) and hypertrophic cardiomyopathy (15/34; 44% cases). Eventually lactic acidosis and hypertrophic cardiomyopathy are described in 35/35 (100%) and 27/34 (79%) of patients with MTO1 deficiency, respectively; with global developmental delay/intellectual disability present in 28/29 (97%), feeding difficulties in 17/35 (49%), failure to thrive in 12/35 (34%), seizures in 12/35 (34%), optic atrophy in 11/21 (52%) and ataxia in 7/34 (21%). There are 19 different pathogenic MTO1 variants identified in these 35 cases: one splice-site, 3 frameshift and 15 missense variants. None have bi-allelic variants that completely inactivate MTO1; however, patients where one variant is truncating (i.e. frameshift) while the second one is a missense appear to have a more severe, even fatal, phenotype. These data suggest that complete loss of MTO1 is not viable. A ketogenic diet may have exerted a favourable effect on seizures in 2/5 patients. CONCLUSION MTO1 deficiency is lethal in some but not all cases, and a genotype-phenotype relation is suggested. Aside from lactic acidosis and cardiomyopathy, developmental delay and other phenotypic features affecting multiple organ systems are often present in these patients, suggesting a broader spectrum than hitherto reported. The diagnosis should be suspected on clinical features and the presence of markers of mitochondrial dysfunction in body fluids, especially low residual complex I, III and IV activity in muscle. Molecular confirmation is required and targeted genomic testing may be the most efficient approach. Although subjective clinical improvement was observed in a small number of patients on therapies such as ketogenic diet and dichloroacetate, no evidence-based effective therapy exists.
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Affiliation(s)
- James J O'Byrne
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Maja Tarailo-Graovac
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, Canada; Institute of Physiology and Biochemistry, Faculty of Biology, The University of Belgrade, Belgrade, Serbia
| | - Aisha Ghani
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Michael Champion
- Department of Inherited Metabolic Disease, Guy's and St Thomas' NHS Foundation Trusts, Evelina London Children's Hospital, London, UK
| | - Charu Deshpande
- Clinical Genetics Unit, Guys and St Thomas' NHS Foundation Trust, London, UK
| | - Ali Dursun
- Hacettepe University, Faculty of Medicine, Institute of Child Health, Department of Pediatric Metabolism, Ankara, Turkey
| | - Riza K Ozgul
- Hacettepe University, Faculty of Medicine, Institute of Child Health, Department of Pediatric Metabolism, Ankara, Turkey
| | - Peter Freisinger
- Department of Pediatrics, Klinikum Reutlingen, Reutlingen, Germany
| | - Ian Garber
- BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Tobias B Haack
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Rita Horvath
- John Walton Muscular Dystrophy Research Centre, Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Ivo Barić
- University Hospital Center Zagreb & School of Medicine, University of Zagreb, Croatia
| | - Ralf A Husain
- Centre for Inborn Metabolic Disorders, Department of Neuropediatrics, Jena University Hospital, Jena, Germany
| | - Leo A J Kluijtmans
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Urania Kotzaeridou
- Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Andrew A Morris
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Colin J Ross
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Saikat Santra
- Department of Clinical Inherited Metabolic Disorders, Birmingham Children's Hospital, Steelhouse Lane, Birmingham, UK
| | - Jan Smeitink
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mark Tarnopolsky
- Department of Pediatrics, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Medical Centre, Hamilton, ON, Canada
| | - Saskia B Wortmann
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Human Genetics, Helmholtz Zentrum Munich, Neuherberg, Germany; Department of Pediatrics, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Salzburg, Austria
| | - Johannes A Mayr
- Department of Pediatrics, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Salzburg, Austria
| | | | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Human Genetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Wyeth W Wasserman
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Ron A Wevers
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Udo F Engelke
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J Rodenburg
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Teck Wah Ting
- Genetics Service, Department of Pediatrics, KK Women's and Children's Hospital, Singapore
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Ramona Salvarinova
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Clara D M van Karnebeek
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada; Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Departments of Pediatrics and Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands.
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63
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Frazier AE, Thorburn DR, Compton AG. Mitochondrial energy generation disorders: genes, mechanisms, and clues to pathology. J Biol Chem 2017; 294:5386-5395. [PMID: 29233888 DOI: 10.1074/jbc.r117.809194] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Inherited disorders of oxidative phosphorylation cause the clinically and genetically heterogeneous diseases known as mitochondrial energy generation disorders, or mitochondrial diseases. Over the last three decades, mutations causing these disorders have been identified in almost 290 genes, but many patients still remain without a molecular diagnosis. Moreover, while our knowledge of the genetic causes is continually expanding, our understanding into how these defects lead to cellular dysfunction and organ pathology is still incomplete. Here, we review recent developments in disease gene discovery, functional characterization, and shared pathogenic parameters influencing disease pathology that offer promising avenues toward the development of effective therapies.
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Affiliation(s)
- Ann E Frazier
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and
| | - David R Thorburn
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and.,Victorian Clinical Genetic Services, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Alison G Compton
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and
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64
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Zhou M, Xue L, Chen Y, Li H, He Q, Wang B, Meng F, Wang M, Guan MX. A hypertension-associated mitochondrial DNA mutation introduces an m 1G37 modification into tRNA Met, altering its structure and function. J Biol Chem 2017; 293:1425-1438. [PMID: 29222331 DOI: 10.1074/jbc.ra117.000317] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/13/2017] [Indexed: 12/20/2022] Open
Abstract
Defective nucleotide modifications of mitochondrial tRNAs have been associated with several human diseases, but their pathophysiology remains poorly understood. In this report, we investigated the pathogenic molecular mechanism underlying a hypertension-associated 4435A→G mutation in mitochondrial tRNAMet The m.4435A→G mutation affected a highly conserved adenosine at position 37, 3' adjacent to the tRNA's anticodon, which is important for the fidelity of codon recognition and stabilization. We hypothesized that the m.4435A→G mutation introduced an m1G37 modification of tRNAMet, altering its structure and function. Primer extension and methylation activity assays indeed confirmed that the m.4435A→G mutation created a tRNA methyltransferase 5 (TRMT5)-catalyzed m1G37 modification of tRNAMet We found that this mutation altered the tRNAMet structure, indicated by an increased melting temperature and electrophoretic mobility of the mutated tRNA compared with the wildtype molecule. We demonstrated that cybrid cell lines carrying the m.4435A→G mutation exhibited significantly decreased efficiency in aminoacylation and steady-state levels of tRNAMet, as compared with those of control cybrids. The aberrant tRNAMet metabolism resulted in variable decreases in mitochondrial DNA (mtDNA)-encoded polypeptides in the mutant cybrids. Furthermore, we found that the m.4435A→G mutation caused respiratory deficiency, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in mutant cybrids. These results demonstrated that an aberrant m1G37 modification of mitochondrial tRNAMet affected the structure and function of its tRNA and consequently altered mitochondrial function. Our findings provide critical insights into the pathophysiology of maternally inherited hypertension, which is manifested by the deficient tRNA nucleotide modification.
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Affiliation(s)
- Mi Zhou
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Ling Xue
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Yaru Chen
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Haiying Li
- the Department of Cardiology, the First Affiliated Hospital, Wenzhou Medical University, Wenzhou, 325035 Zhejiang, China
| | - Qiufen He
- the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Bibin Wang
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Feilong Meng
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Meng Wang
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Min-Xin Guan
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China, .,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, 310058 Zhejiang, China, and.,the Joining Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, 310058 Zhejiang, China
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65
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Sokołowski M, Klassen R, Bruch A, Schaffrath R, Glatt S. Cooperativity between different tRNA modifications and their modification pathways. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1861:409-418. [PMID: 29222069 DOI: 10.1016/j.bbagrm.2017.12.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/30/2017] [Accepted: 12/03/2017] [Indexed: 12/11/2022]
Abstract
Ribonucleotide modifications perform a wide variety of roles in synthesis, turnover and functionality of tRNA molecules. The presence of particular chemical moieties can refine the internal interaction network within a tRNA molecule, influence its thermodynamic stability, contribute novel chemical properties and affect its decoding behavior during mRNA translation. As the lack of specific modifications in the anticodon stem and loop causes disrupted proteome homeostasis, diminished response to stress conditions, and the onset of human diseases, the underlying modification cascades have recently gained particular scientific and clinical interest. Nowadays, a complicated but conclusive image of the interconnectivity between different enzymatic modification cascades and their resulting tRNA modifications emerges. Here we summarize the current knowledge in the field, focusing on the known instances of cross talk among the enzymatic tRNA modification pathways and the consequences on the dynamic regulation of the tRNA modificome by various factors. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
- Mikołaj Sokołowski
- Max Planck Research Group at the Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland; Postgraduate School of Molecular Medicine, Warsaw, Poland
| | - Roland Klassen
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, Kassel, Germany
| | - Alexander Bruch
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, Kassel, Germany
| | - Raffael Schaffrath
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, Kassel, Germany.
| | - Sebastian Glatt
- Max Planck Research Group at the Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.
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66
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Dewe JM, Fuller BL, Lentini JM, Kellner SM, Fu D. TRMT1-Catalyzed tRNA Modifications Are Required for Redox Homeostasis To Ensure Proper Cellular Proliferation and Oxidative Stress Survival. Mol Cell Biol 2017; 37:e00214-17. [PMID: 28784718 PMCID: PMC5640816 DOI: 10.1128/mcb.00214-17] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 05/17/2017] [Accepted: 07/29/2017] [Indexed: 02/07/2023] Open
Abstract
Mutations in the tRNA methyltransferase 1 (TRMT1) gene have been identified as the cause of certain forms of autosomal-recessive intellectual disability (ID). However, the molecular pathology underlying ID-associated TRMT1 mutations is unknown, since the biological role of the encoded TRMT1 protein remains to be determined. Here, we have elucidated the molecular targets and function of TRMT1 to uncover the cellular effects of ID-causing TRMT1 mutations. Using human cells that have been rendered deficient in TRMT1, we show that TRMT1 is responsible for catalyzing the dimethylguanosine (m2,2G) base modification in both nucleus- and mitochondrion-encoded tRNAs. TRMT1-deficient cells exhibit decreased proliferation rates, alterations in global protein synthesis, and perturbations in redox homeostasis, including increased endogenous ROS levels and hypersensitivity to oxidizing agents. Notably, ID-causing TRMT1 variants are unable to catalyze the formation of m2,2G due to defects in RNA binding and cannot rescue oxidative stress sensitivity. Our results uncover a biological role for TRMT1-catalyzed tRNA modification in redox metabolism and show that individuals with TRMT1-associated ID are likely to have major perturbations in cellular homeostasis due to the lack of m2,2G modifications.
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Affiliation(s)
- Joshua M Dewe
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | - Benjamin L Fuller
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | - Jenna M Lentini
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
| | | | - Dragony Fu
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, New York, USA
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67
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Garone C, D’Souza AR, Dallabona C, Lodi T, Rebelo-Guiomar P, Rorbach J, Donati MA, Procopio E, Montomoli M, Guerrini R, Zeviani M, Calvo SE, Mootha VK, DiMauro S, Ferrero I, Minczuk M. Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome. Hum Mol Genet 2017; 26:4257-4266. [PMID: 28973171 PMCID: PMC5886288 DOI: 10.1093/hmg/ddx314] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/01/2017] [Accepted: 08/03/2017] [Indexed: 02/02/2023] Open
Abstract
Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2'-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2'-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation.
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Affiliation(s)
- Caterina Garone
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Aaron R D’Souza
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Cristina Dallabona
- Department of Chemistry, Life Sciences and Environmental Sustainability - University of Parma, Parma 43121, Italy
| | - Tiziana Lodi
- Department of Chemistry, Life Sciences and Environmental Sustainability - University of Parma, Parma 43121, Italy
| | - Pedro Rebelo-Guiomar
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
- Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, 4099-002, Portugal
| | - Joanna Rorbach
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | | | - Elena Procopio
- Metabolic Unit, A. Meyer Children's Hospital, Florence 50139, Italy
| | - Martino Montomoli
- Pediatric Neurology Unit and Laboratories, “A. Meyer” Children's Hospital, University of Florence, 50139, Italy
| | - Renzo Guerrini
- Pediatric Neurology Unit and Laboratories, “A. Meyer” Children's Hospital, University of Florence, 50139, Italy
| | - Massimo Zeviani
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Sarah E Calvo
- Broad Institute of MIT & Harvard, Cambridge, MA 02142, USA
- Department of Molecular Biology and Howard Hughes Medical Institute, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Vamsi K Mootha
- Department of Molecular Biology and Howard Hughes Medical Institute, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Ileana Ferrero
- Department of Chemistry, Life Sciences and Environmental Sustainability - University of Parma, Parma 43121, Italy
| | - Michal Minczuk
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
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68
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Marín M, Fernández-Calero T, Ehrlich R. Protein folding and tRNA biology. Biophys Rev 2017; 9:573-588. [PMID: 28944442 PMCID: PMC5662057 DOI: 10.1007/s12551-017-0322-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 08/28/2017] [Indexed: 12/14/2022] Open
Abstract
Polypeptides can fold into tertiary structures while they are synthesized by the ribosome. In addition to the amino acid sequence, protein folding is determined by several factors within the cell. Among others, the folding pathway of a nascent polypeptide can be affected by transient interactions with other proteins, ligands, or the ribosome, as well as by the translocation through membrane pores. Particularly, the translation machinery and the population of tRNA under different physiological or adaptive responses can dramatically affect protein folding. This review summarizes the scientific evidence describing the role of translation kinetics and tRNA populations on protein folding and addresses current efforts to better understand tRNA biology. It is organized into three main parts, which are focused on: (i) protein folding in the cellular context; (ii) tRNA biology and the complexity of the tRNA population; and (iii) available methods and technical challenges in the characterization of tRNA pools. In this manner, this work illustrates the ways by which functional properties of proteins may be modulated by cellular tRNA populations.
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Affiliation(s)
- Mónica Marín
- Biochemistry-Molecular Biology Section, Cellular and Molecular Biology Department, Faculty of Sciences, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
| | - Tamara Fernández-Calero
- Biochemistry-Molecular Biology Section, Cellular and Molecular Biology Department, Faculty of Sciences, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
- Bioinformatics Unit, Institut Pasteur Montevideo, Mataojo 2020, 11400 Montevideo, Uruguay
| | - Ricardo Ehrlich
- Biochemistry-Molecular Biology Section, Cellular and Molecular Biology Department, Faculty of Sciences, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay
- Institut Pasteur Montevideo, Mataojo 2020, 11400 Montevideo, Uruguay
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69
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Bacusmo JM, Orsini SS, Hu J, DeMott M, Thiaville PC, Elfarash A, Paulines MJ, Rojas-Benítez D, Meineke B, Deutsch C, Iwata-Reuyl D, Limbach PA, Dedon PC, Rice KC, Shuman S, Crécy-Lagard VD. The t 6A modification acts as a positive determinant for the anticodon nuclease PrrC, and is distinctively nonessential in Streptococcus mutans. RNA Biol 2017; 15:508-517. [PMID: 28726545 DOI: 10.1080/15476286.2017.1353861] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Endoribonuclease toxins (ribotoxins) are produced by bacteria and fungi to respond to stress, eliminate non-self competitor species, or interdict virus infection. PrrC is a bacterial ribotoxin that targets and cleaves tRNALysUUU in the anticodon loop. In vitro studies suggested that the post-transcriptional modification threonylcarbamoyl adenosine (t6A) is required for PrrC activity but this prediction had never been validated in vivo. Here, by using t6A-deficient yeast derivatives, it is shown that t6A is a positive determinant for PrrC proteins from various bacterial species. Streptococcus mutans is one of the few bacteria where the t6A synthesis gene tsaE (brpB) is dispensable and its genome encodes a PrrC toxin. We had previously shown using an HPLC-based assay that the S. mutans tsaE mutant was devoid of t6A. However, we describe here a novel and a more sensitive hybridization-based t6A detection method (compared to HPLC) that showed t6A was still present in the S. mutans ΔtsaE, albeit at greatly reduced levels (93% reduced compared with WT). Moreover, mutants in 2 other S. mutans t6A synthesis genes (tsaB and tsaC) were shown to be totally devoid of the modification thus confirming its dispensability in this organism. Furthermore, analysis of t6A modification ratios and of t6A synthesis genes mRNA levels in S. mutans suggest they may be regulated by growth phase.
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Affiliation(s)
- Jo Marie Bacusmo
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA
| | - Silvia S Orsini
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA
| | - Jennifer Hu
- b Center for Environmental Health Sciences, Department of Biological Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Michael DeMott
- b Center for Environmental Health Sciences, Department of Biological Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Patrick C Thiaville
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA.,c Genetics and Genomics Graduate Program , University of Florida , Gainesville , USA.,d University of Florida Genetics Institute, University of Florida , Gainesville , FL , USA
| | - Ameer Elfarash
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA.,e Genetic Department, Faculty of Agriculture , Assiut University , Assuit , Egypt
| | - Mellie June Paulines
- f Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry , University of Cincinnati , Cincinnati OH , USA
| | - Diego Rojas-Benítez
- g Centro de Regulación del Genoma. Facultad de Ciencias - Universidad de Chile , Santiago , Chile
| | - Birthe Meineke
- h Molecular Biology Program , Sloan-Kettering Institute , New York , NY , USA
| | - Chris Deutsch
- i Department of Chemistry , Portland State University , Portland , OR , USA
| | - Dirk Iwata-Reuyl
- i Department of Chemistry , Portland State University , Portland , OR , USA
| | - Patrick A Limbach
- f Rieveschl Laboratories for Mass Spectrometry, Department of Chemistry , University of Cincinnati , Cincinnati OH , USA
| | - Peter C Dedon
- b Center for Environmental Health Sciences, Department of Biological Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Kelly C Rice
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA
| | - Stewart Shuman
- h Molecular Biology Program , Sloan-Kettering Institute , New York , NY , USA
| | - Valérie de Crécy-Lagard
- a Department of Microbiology and Cell Science, IFAS , University of Florida , Gainesville , FL , USA.,d University of Florida Genetics Institute, University of Florida , Gainesville , FL , USA
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70
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Bohnsack MT, Sloan KE. The mitochondrial epitranscriptome: the roles of RNA modifications in mitochondrial translation and human disease. Cell Mol Life Sci 2017; 75:241-260. [PMID: 28752201 PMCID: PMC5756263 DOI: 10.1007/s00018-017-2598-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 07/08/2017] [Accepted: 07/17/2017] [Indexed: 11/28/2022]
Abstract
Mitochondrial protein synthesis is essential for the production of components of the oxidative phosphorylation system. RNA modifications in the mammalian mitochondrial translation apparatus play key roles in facilitating mitochondrial gene expression as they enable decoding of the non-conventional genetic code by a minimal set of tRNAs, and efficient and accurate protein synthesis by the mitoribosome. Intriguingly, recent transcriptome-wide analyses have also revealed modifications in mitochondrial mRNAs, suggesting that the concept of dynamic regulation of gene expression by the modified RNAs (the “epitranscriptome”) extends to mitochondria. Furthermore, it has emerged that defects in RNA modification, arising from either mt-DNA mutations or mutations in nuclear-encoded mitochondrial modification enzymes, underlie multiple mitochondrial diseases. Concomitant advances in the identification of the mitochondrial RNA modification machinery and recent structural views of the mitochondrial translation apparatus now allow the molecular basis of such mitochondrial diseases to be understood on a mechanistic level.
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Affiliation(s)
- Markus T Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
- Göttingen Centre for Molecular Biosciences, University of Göttingen, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
| | - Katherine E Sloan
- Department of Molecular Biology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
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71
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Read DF, Waller TJ, Tse E, Southworth DR, Engelke DR, Smaldino PJ. Aggregation of Mod5 is affected by tRNA binding with implications for tRNA gene-mediated silencing. FEBS Lett 2017; 591:1601-1610. [PMID: 28303570 DOI: 10.1002/1873-3468.12627] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/09/2017] [Accepted: 03/13/2017] [Indexed: 12/24/2022]
Abstract
Mod5 is a multifunctional protein that modifies a subset of tRNAs in the cytoplasm and is also required for an RNA-mediated form of transcriptional silencing. Previous in vivo studies have shown that the nuclear silencing function of Mod5 does not require that the causative tRNA gene encode a Mod5 substrate, although Mod5 is still required. However, previous data have not directly tested whether Mod5 can directly bind substrate and nonsubstrate RNAs. We herein demonstrate that Mod5 directly binds to both substrate and nonsubstrate RNAs, including a highly structured, non-tRNA sequence (5S-rRNA), consistent with previous in vivo data. Furthermore, we show that some RNAs drastically change the aggregation behavior of Mod5 with implications for tRNA gene-mediated silencing.
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Affiliation(s)
- David F Read
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Thomas J Waller
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Eric Tse
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Daniel R Southworth
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - David R Engelke
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,University of Colorado Denver/Anschutz Medical Campus, Aurora, CO, USA
| | - Philip J Smaldino
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Biology, Ball State University, Muncie, IN, USA
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72
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Maraia RJ, Arimbasseri AG. Factors That Shape Eukaryotic tRNAomes: Processing, Modification and Anticodon-Codon Use. Biomolecules 2017; 7:biom7010026. [PMID: 28282871 PMCID: PMC5372738 DOI: 10.3390/biom7010026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 02/24/2017] [Indexed: 01/24/2023] Open
Abstract
Transfer RNAs (tRNAs) contain sequence diversity beyond their anticodons and the large variety of nucleotide modifications found in all kingdoms of life. Some modifications stabilize structure and fit in the ribosome whereas those to the anticodon loop modulate messenger RNA (mRNA) decoding activity more directly. The identities of tRNAs with some universal anticodon loop modifications vary among distant and parallel species, likely to accommodate fine tuning for their translation systems. This plasticity in positions 34 (wobble) and 37 is reflected in codon use bias. Here, we review convergent evidence that suggest that expansion of the eukaryotic tRNAome was supported by its dedicated RNA polymerase III transcription system and coupling to the precursor-tRNA chaperone, La protein. We also review aspects of eukaryotic tRNAome evolution involving G34/A34 anticodon-sparing, relation to A34 modification to inosine, biased codon use and regulatory information in the redundancy (synonymous) component of the genetic code. We then review interdependent anticodon loop modifications involving position 37 in eukaryotes. This includes the eukaryote-specific tRNA modification, 3-methylcytidine-32 (m3C32) and the responsible gene, TRM140 and homologs which were duplicated and subspecialized for isoacceptor-specific substrates and dependence on i6A37 or t6A37. The genetics of tRNA function is relevant to health directly and as disease modifiers.
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Affiliation(s)
- Richard J Maraia
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
- Commissioned Corps, U.S. Public Health Service, Rockville, MD, 20016, USA.
| | - Aneeshkumar G Arimbasseri
- Molecular Genetics Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
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73
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Kernohan KD, Dyment DA, Pupavac M, Cramer Z, McBride A, Bernard G, Straub I, Tetreault M, Hartley T, Huang L, Sell E, Majewski J, Rosenblatt DS, Shoubridge E, Mhanni A, Myers T, Proud V, Vergano S, Spangler B, Farrow E, Kussman J, Safina N, Saunders C, Boycott KM, Thiffault I. Matchmaking facilitates the diagnosis of an autosomal-recessive mitochondrial disease caused by biallelic mutation of the tRNA isopentenyltransferase (TRIT1
) gene. Hum Mutat 2017; 38:511-516. [DOI: 10.1002/humu.23196] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 02/07/2017] [Accepted: 02/07/2017] [Indexed: 01/14/2023]
Affiliation(s)
- Kristin D. Kernohan
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
| | - David A. Dyment
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
- Department of Genetics; Children's Hospital of Eastern Ontario; Ottawa Ontario Canada
| | - Mihaela Pupavac
- Department of Human Genetics; McGill University; Montréal Québec Canada
| | - Zvi Cramer
- Department of Human Genetics; McGill University; Montréal Québec Canada
| | - Arran McBride
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
| | - Genevieve Bernard
- Department of Human Genetics; McGill University; Montréal Québec Canada
| | - Isabella Straub
- Department of Human Genetics; McGill University; Montréal Québec Canada
| | - Martine Tetreault
- McGill University and Genome Quebec Innovation Centre; Montreal Quebec Canada
| | - Taila Hartley
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
| | - Lijia Huang
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
| | - Erick Sell
- Division of Neurology; Children's Hospital of Eastern Ontario; Ottawa Ontario Canada
| | - Jacek Majewski
- Department of Human Genetics; McGill University; Montréal Québec Canada
- McGill University and Genome Quebec Innovation Centre; Montreal Quebec Canada
| | | | - Eric Shoubridge
- Department of Human Genetics; McGill University; Montréal Québec Canada
| | - Aziz Mhanni
- Section of Genetics and Metabolism; Children's Hospital and the Department of Pediatrics and Child Health; University of Manitoba; Winnipeg Manitoba Canada
| | - Tara Myers
- Department of Pediatrics; Children's Mercy Hospitals; Kansas City Missouri
| | - Virginia Proud
- Division of Medical Genetics and Metabolism; Children's Hospital of the King's Daughters; Norfolk Virginia
| | - Samanta Vergano
- Division of Medical Genetics and Metabolism; Children's Hospital of the King's Daughters; Norfolk Virginia
| | - Brooke Spangler
- Division of Medical Genetics and Metabolism; Children's Hospital of the King's Daughters; Norfolk Virginia
| | - Emily Farrow
- Center for Pediatric Genomic Medicine; Children's Mercy Hospital; Kansas City Missouri
- University of Missouri-Kansas City School of Medicine; Kansas City Missouri
| | - Jennifer Kussman
- Department of Pediatrics; Children's Mercy Hospitals; Kansas City Missouri
| | - Nicole Safina
- Department of Pediatrics; Children's Mercy Hospitals; Kansas City Missouri
| | - Carol Saunders
- Center for Pediatric Genomic Medicine; Children's Mercy Hospital; Kansas City Missouri
- University of Missouri-Kansas City School of Medicine; Kansas City Missouri
| | - Kym M. Boycott
- Children's Hospital of Eastern Ontario Research Institute; Ottawa Ontario Canada
- Department of Genetics; Children's Hospital of Eastern Ontario; Ottawa Ontario Canada
| | - Isabelle Thiffault
- Center for Pediatric Genomic Medicine; Children's Mercy Hospital; Kansas City Missouri
- University of Missouri-Kansas City School of Medicine; Kansas City Missouri
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Dealing with an Unconventional Genetic Code in Mitochondria: The Biogenesis and Pathogenic Defects of the 5-Formylcytosine Modification in Mitochondrial tRNA Met. Biomolecules 2017; 7:biom7010024. [PMID: 28257121 PMCID: PMC5372736 DOI: 10.3390/biom7010024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/24/2017] [Indexed: 01/13/2023] Open
Abstract
Human mitochondria contain their own genome, which uses an unconventional genetic code. In addition to the standard AUG methionine codon, the single mitochondrial tRNA Methionine (mt-tRNAMet) also recognises AUA during translation initiation and elongation. Post-transcriptional modifications of tRNAs are important for structure, stability, correct folding and aminoacylation as well as decoding. The unique 5-formylcytosine (f5C) modification of position 34 in mt-tRNAMet has been long postulated to be crucial for decoding of unconventional methionine codons and efficient mitochondrial translation. However, the enzymes responsible for the formation of mitochondrial f5C have been identified only recently. The first step of the f5C pathway consists of methylation of cytosine by NSUN3. This is followed by further oxidation by ABH1. Here, we review the role of f5C, the latest breakthroughs in our understanding of the biogenesis of this unique mitochondrial tRNA modification and its involvement in human disease.
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75
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Schweizer U, Bohleber S, Fradejas-Villar N. The modified base isopentenyladenosine and its derivatives in tRNA. RNA Biol 2017; 14:1197-1208. [PMID: 28277934 PMCID: PMC5699536 DOI: 10.1080/15476286.2017.1294309] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Base 37 in tRNA, 3′-adjacent to the anticodon, is occupied by a purine base that is thought to stabilize codon recognition by stacking interactions on the first Watson-Crick base pair. If the first codon position forms an A.U or U.A base pair, the purine is likely further modified in all domains of life. One of the first base modifications found in tRNA is N6-isopentenyl adenosine (i6A) present in a fraction of tRNAs in bacteria and eukaryotes, which can be further modified to 2-methyl-thio-N6-isopentenyladenosine (ms2i6A) in a subset of tRNAs. Homologous tRNA isopentenyl transferase enzymes have been identified in bacteria (MiaA), yeast (Mod5, Tit1), roundworm (GRO-1), and mammals (TRIT1). In eukaryotes, isopentenylation of cytoplasmic and mitochondrial tRNAs is mediated by products of the same gene. Accordingly, a patient with homozygous mutations in TRIT1 has mitochondrial disease. The role of i6A in a subset of tRNAs in gene expression has been linked with translational fidelity, speed of translation, skewed gene expression, and non-sense suppression. This review will not cover the action of i6A as a cytokinin in plants or the potential function of Mod5 as a prion in yeast.
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Affiliation(s)
- Ulrich Schweizer
- a Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn , Bonn , Germany
| | - Simon Bohleber
- a Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn , Bonn , Germany
| | - Noelia Fradejas-Villar
- a Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn , Bonn , Germany
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76
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Abstract
Cells adapt to their environment by linking external stimuli to an intricate network of transcriptional, post-transcriptional and translational processes. Among these, mechanisms that couple environmental cues to the regulation of protein translation are not well understood. Chemical modifications of RNA allow rapid cellular responses to external stimuli by modulating a wide range of fundamental biochemical properties and processes, including the stability, splicing and translation of messenger RNA. In this Review, we focus on the occurrence of N6-methyladenosine (m6A), 5-methylcytosine (m5C) and pseudouridine (Ψ) in RNA, and describe how these RNA modifications are implicated in regulating pluripotency, stem cell self-renewal and fate specification. Both post-transcriptional modifications and the enzymes that catalyse them modulate stem cell differentiation pathways and are essential for normal development.
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Affiliation(s)
- Michaela Frye
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute, Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Sandra Blanco
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute, Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
- CIC bioGUNE, Bizkaia Technology Park, Building 801A, Derio, Bizkaia 48160, Spain
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77
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Waller TJ, Read DF, Engelke DR, Smaldino PJ. The human tRNA-modifying protein, TRIT1, forms amyloid fibers in vitro. Gene 2016; 612:19-24. [PMID: 27984194 DOI: 10.1016/j.gene.2016.10.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/24/2016] [Accepted: 10/27/2016] [Indexed: 12/19/2022]
Abstract
TRIT1 is a highly conserved tRNA isopentenyl transferase that modifies a subset of tRNAs in human cells and is a candidate tumor suppressor in lung cancer in certain ethnic populations. The yeast homologue, Mod5, has similar tRNA-modifying functions in the cytoplasm and is required for the transcriptional silencing activity of RNA polymerase II promoters near tRNA genes in the nucleus, a phenomenon termed tRNA gene mediated (tgm) silencing. Furthermore, Mod5 can fold into amyloid fibers in vitro and in vivo, which confers resistance to certain fungicides in yeast. Since TRIT1 complements both tRNA modifying and tgm-silencing activities in yeast where the Mod5 gene has been deleted, it seemed possible that TRIT1 might also have amyloid-forming capabilities. Here we show that TRIT1, like Mod5, directly binds to tRNAs that are both substrate and non-substrates for modification with similar affinity, and to an unstructured, non-tRNA. Binding appears to involve distinct protein-RNA multimers which decrease in electrophoretic mobility as the protein to RNA ratio increases. Furthermore, we characterize TRIT1 as a novel human amyloid fiber forming protein. We discuss these data in light of TRIT1's functional roles and possible implications for disease.
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Affiliation(s)
- T J Waller
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - D F Read
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - D R Engelke
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States; University of Denver, Aurora, CO 80045, United States.
| | - P J Smaldino
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States; Biology, Ball State University, Muncie, IN 47306, United States.
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78
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Arimbasseri AG, Iben J, Wei FY, Rijal K, Tomizawa K, Hafner M, Maraia RJ. Evolving specificity of tRNA 3-methyl-cytidine-32 (m3C32) modification: a subset of tRNAsSer requires N6-isopentenylation of A37. RNA (NEW YORK, N.Y.) 2016; 22:1400-10. [PMID: 27354703 PMCID: PMC4986895 DOI: 10.1261/rna.056259.116] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/24/2016] [Indexed: 05/10/2023]
Abstract
Post-transcriptional modifications of anticodon loop (ACL) nucleotides impact tRNA structure, affinity for the ribosome, and decoding activity, and these activities can be fine-tuned by interactions between nucleobases on either side of the anticodon. A recently discovered ACL modification circuit involving positions 32, 34, and 37 is disrupted by a human disease-associated mutation to the gene encoding a tRNA modification enzyme. We used tRNA-HydroSeq (-HySeq) to examine (3)methyl-cytidine-32 (m(3)C32), which is found in yeast only in the ACLs of tRNAs(Ser) and tRNAs(Thr) In contrast to that reported for Saccharomyces cerevisiae in which all m(3)C32 depends on a single gene, TRM140, the m(3)C32 of tRNAs(Ser) and tRNAs(Thr) of the fission yeast S. pombe, are each dependent on one of two related genes, trm140(+) and trm141(+), homologs of which are found in higher eukaryotes. Interestingly, mammals and other vertebrates contain a third homolog and also contain m(3)C at new sites, positions 32 on tRNAs(Arg) and C47:3 in the variable arm of tRNAs(Ser) More significantly, by examining S. pombe mutants deficient for other modifications, we found that m(3)C32 on the three tRNAs(Ser) that contain anticodon base A36, requires N(6)-isopentenyl modification of A37 (i(6)A37). This new C32-A37 ACL circuitry indicates that i(6)A37 is a pre- or corequisite for m(3)C32 on these tRNAs. Examination of the tRNA database suggests that such circuitry may be more expansive than observed here. The results emphasize two contemporary themes, that tRNA modifications are interconnected, and that some specific modifications on tRNAs of the same anticodon identity are species-specific.
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Affiliation(s)
- Aneeshkumar G Arimbasseri
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - James Iben
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, 860-0862 Kumamoto, Japan
| | - Keshab Rijal
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, 860-0862 Kumamoto, Japan
| | - Markus Hafner
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard J Maraia
- Commissioned Corps, US Public Health Service, Washington, DC 20201, USA
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Xue L, Wang M, Li H, Wang H, Jiang F, Hou L, Geng J, Lin Z, Peng Y, Zhou H, Yu H, Jiang P, Mo JQ, Guan MX. Mitochondrial tRNA mutations in 2070 Chinese Han subjects with hypertension. Mitochondrion 2016; 30:208-21. [PMID: 27544295 DOI: 10.1016/j.mito.2016.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/21/2016] [Accepted: 08/16/2016] [Indexed: 12/28/2022]
Abstract
BACKGROUND Mitochondria have the profound impact on vascular function in both health and disease. However, mitochondrial genetic determinants for the development of hypertension remain poorly explored. METHODS AND RESULTS The Sanger sequence analysis of 22 mitochondrial tRNA genes were performed in a cohort of 2070 Han Chinese hypertensive and 512 control subjects. This analysis identified 165 variants among 22 tRNA genes. These variants were evaluated for the pathogenicity using the following criteria: (1) present in <1% of the controls; (2) evolutional conservation; (3) potential structural and functional alterations. We identified 47 (5 known and 42 novel/putative) hypertension-associated tRNA variants in 80 hypertensive subjects. These variants could have potential structural alterations and functional significance of tRNAs. By using lymphoblastoid cell lines derived from 6 probands carrying one of 6 represented variants (tRNA(Ala) 5655T>C, tRNA(Gly) 10003T>C, tRNA(Leu(UUR)) 3253T>C, tRNA(Asp) 7551A>G, tRNA(Glu) 14692A>G, tRNA(Thr) 15909A>G) and 6 control subjects lacking these variants, we showed marked reductions in the steady-state level of corresponding 5 tRNAs, but not tRNA(Thr), in mutant cell lines, compared with control cells lines. The various decreases in the activities of complexes I, III and IV were observed in mutant cells carrying one of five tRNA variants, except tRNA(Thr) 15909A>G variant. The deficient respirations were responsible for the decrease in the mitochondrial ATP production and increasing production of reactive oxygen species in mutant cell lines carrying one of five tRNA variants. CONCLUSION Mitochondrial tRNA variants are the important causes of hypertension, accounting for 3.9% cases of 2070 Han Chinese hypertensive subjects. Our findings may provide new insights into the pathophysiology of hypertension that were manifested by mitochondrial dysfunction.
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Affiliation(s)
- Ling Xue
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Meng Wang
- Institute of Genetics, Zhejiang University, Department of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Haiying Li
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Department of Cardiology, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Heng Wang
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Feng Jiang
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Lingling Hou
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Junwei Geng
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zhi Lin
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yanyan Peng
- Institute of Genetics, Zhejiang University, Department of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Hong Zhou
- Institute of Genetics, Zhejiang University, Department of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Han Yu
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Pingping Jiang
- Institute of Genetics, Zhejiang University, Department of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jun Qin Mo
- Department of Pathology, Rady Children's Hospital, University of California San Diego School of Medicine, San Diego, CA, USA
| | - Min-Xin Guan
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Institute of Genetics, Zhejiang University, Department of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China; Joining Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang, China.
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80
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Duechler M, Leszczyńska G, Sochacka E, Nawrot B. Nucleoside modifications in the regulation of gene expression: focus on tRNA. Cell Mol Life Sci 2016; 73:3075-95. [PMID: 27094388 PMCID: PMC4951516 DOI: 10.1007/s00018-016-2217-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Both, DNA and RNA nucleoside modifications contribute to the complex multi-level regulation of gene expression. Modified bases in tRNAs modulate protein translation rates in a highly dynamic manner. Synonymous codons, which differ by the third nucleoside in the triplet but code for the same amino acid, may be utilized at different rates according to codon-anticodon affinity. Nucleoside modifications in the tRNA anticodon loop can favor the interaction with selected codons by stabilizing specific base pairs. Similarly, weakening of base pairing can discriminate against binding to near-cognate codons. mRNAs enriched in favored codons are translated in higher rates constituting a fine-tuning mechanism for protein synthesis. This so-called codon bias establishes a basic protein level, but sometimes it is necessary to further adjust the production rate of a particular protein to actual requirements, brought by, e.g., stages in circadian rhythms, cell cycle progression or exposure to stress. Such an adjustment is realized by the dynamic change of tRNA modifications resulting in the preferential translation of mRNAs coding for example for stress proteins to facilitate cell survival. Furthermore, tRNAs contribute in an entirely different way to another, less specific stress response consisting in modification-dependent tRNA cleavage that contributes to the general down-regulation of protein synthesis. In this review, we summarize control functions of nucleoside modifications in gene regulation with a focus on recent findings on protein synthesis control by tRNA base modifications.
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Affiliation(s)
- Markus Duechler
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland.
| | - Grażyna Leszczyńska
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Elzbieta Sochacka
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Barbara Nawrot
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
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81
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Schweizer U, Fradejas‐Villar N. Why 21? The significance of selenoproteins for human health revealed by inborn errors of metabolism. FASEB J 2016; 30:3669-3681. [DOI: 10.1096/fj.201600424] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 07/18/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Ulrich Schweizer
- Institut für Biochemie und MolekularbiologieRheinische Friedrich‐Wilhelms‐Universitfät Bonn Bonn Germany
| | - Noelia Fradejas‐Villar
- Institut für Biochemie und MolekularbiologieRheinische Friedrich‐Wilhelms‐Universitfät Bonn Bonn Germany
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82
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Wedatilake Y, Niazi R, Fassone E, Powell CA, Pearce S, Plagnol V, Saldanha JW, Kleta R, Chong WK, Footitt E, Mills PB, Taanman JW, Minczuk M, Clayton PT, Rahman S. TRNT1 deficiency: clinical, biochemical and molecular genetic features. Orphanet J Rare Dis 2016; 11:90. [PMID: 27370603 PMCID: PMC4930608 DOI: 10.1186/s13023-016-0477-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/24/2016] [Indexed: 11/10/2022] Open
Abstract
Background TRNT1 (CCA-adding transfer RNA nucleotidyl transferase) enzyme deficiency is a new metabolic disease caused by defective post-transcriptional modification of mitochondrial and cytosolic transfer RNAs (tRNAs). Results We investigated four patients from two families with infantile-onset cyclical, aseptic febrile episodes with vomiting and diarrhoea, global electrolyte imbalance during these episodes, sideroblastic anaemia, B lymphocyte immunodeficiency, retinitis pigmentosa, hepatosplenomegaly, exocrine pancreatic insufficiency and renal tubulopathy. Other clinical features found in children include sensorineural deafness, cerebellar atrophy, brittle hair, partial villous atrophy and nephrocalcinosis. Whole exome sequencing and bioinformatic filtering were utilised to identify recessive compound heterozygous TRNT1 mutations (missense mutation c.668T>C, p.Ile223Thr and a novel splice mutation c.342+5G>T) segregating with disease in the first family. The second family was found to have a homozygous TRNT1 mutation (c.569G>T), p.Arg190Ile, (previously published). We found normal mitochondrial translation products using passage matched controls and functional perturbation of 3’ CCA addition to mitochondrial tRNAs (tRNACys, tRNALeuUUR and tRNAHis) in fibroblasts from two patients, demonstrating a pathomechanism affecting the CCA addition to mt-tRNAs. Acute management of these patients included transfusion for anaemia, fluid and electrolyte replacement and immunoglobulin therapy. We also describe three-year follow-up findings after treatment by bone marrow transplantation in one patient, with resolution of fever and reversal of the abnormal metabolic profile. Conclusions Our report highlights that TRNT1 mutations cause a spectrum of disease ranging from a childhood-onset complex disease with manifestations in most organs to an adult-onset isolated retinitis pigmentosa presentation. Systematic review of all TRNT1 cases and mutations reported to date revealed a distinctive phenotypic spectrum and metabolic and other investigative findings, which will facilitate rapid clinical recognition of future cases.
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Affiliation(s)
- Yehani Wedatilake
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Rojeen Niazi
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Elisa Fassone
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | | | | | | | - José W Saldanha
- Division of Mathematical Biology, National Institute for Medical Research, Mill Hill, London, UK
| | - Robert Kleta
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK.,UCL Genetics Institute, London, UK.,Division of Medicine, UCL, London, UK
| | - W Kling Chong
- Radiology Department, Great Ormond Street Hospital, London, UK
| | - Emma Footitt
- Metabolic medicine department, Great Ormond Street Hospital, London, UK
| | - Philippa B Mills
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK
| | | | - Peter T Clayton
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Shamima Rahman
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK. .,Mitochondrial Research Group, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, 30, Guilford Street, London, WC1N 1EH, UK.
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83
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Zhou M, Long T, Fang ZP, Zhou XL, Liu RJ, Wang ED. Identification of determinants for tRNA substrate recognition by Escherichia coli C/U34 2'-O-methyltransferase. RNA Biol 2016; 12:900-11. [PMID: 26106808 PMCID: PMC4615657 DOI: 10.1080/15476286.2015.1050576] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Post-transcriptional modifications bring chemical diversity to tRNAs, especially at positions 34 and 37 of the anticodon stem-loop (ASL). TrmL is the prokaryotic methyltransferase that catalyzes the transfer of the methyl group from S-adenosyl-L-methionine to the wobble base of tRNALeuCAA and tRNALeuUAA isoacceptors. This Cm34/Um34 modification affects codon-anticodon interactions and is essential for translational fidelity. TrmL-catalyzed 2′-O-methylation requires its homodimerization; however, understanding of the tRNA recognition mechanism by TrmL remains elusive. In the current study, by measuring tRNA methylation by TrmL and performing kinetic analysis of tRNA mutants, we found that TrmL exhibits a fine-tuned tRNA substrate recognition mechanism. Anticodon stem-loop minihelices with an extension of 2 base pairs are the minimal substrate for EcTrmL methylation. A35 is a key residue for TrmL recognition, while A36-A37-A38 are important either via direct interaction with TrmL or due to the necessity for prior isopentenylation (i6) at A37. In addition, TrmL only methylates pyrimidines but not purine residues at the wobble position, and the 2′-O-methylation relies on prior N6-isopentenyladenosine modification at position 37.
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Affiliation(s)
- Mi Zhou
- a State Key Laboratory of Molecular Biology ; Institute of Biochemistry and Cell Biology; Shanghai Institutes for Biological Sciences ; Chinese Academy of Sciences ; Shanghai , PR China
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Metodiev M, Thompson K, Alston C, Morris A, He L, Assouline Z, Rio M, Bahi-Buisson N, Pyle A, Griffin H, Siira S, Filipovska A, Munnich A, Chinnery P, McFarland R, Rötig A, Taylor R. Recessive Mutations in TRMT10C Cause Defects in Mitochondrial RNA Processing and Multiple Respiratory Chain Deficiencies. Am J Hum Genet 2016; 98:993-1000. [PMID: 27132592 PMCID: PMC4863561 DOI: 10.1016/j.ajhg.2016.03.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/14/2016] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial disorders are clinically and genetically diverse, with mutations in mitochondrial or nuclear genes able to cause defects in mitochondrial gene expression. Recently, mutations in several genes encoding factors involved in mt-tRNA processing have been identified to cause mitochondrial disease. Using whole-exome sequencing, we identified mutations in TRMT10C (encoding the mitochondrial RNase P protein 1 [MRPP1]) in two unrelated individuals who presented at birth with lactic acidosis, hypotonia, feeding difficulties, and deafness. Both individuals died at 5 months after respiratory failure. MRPP1, along with MRPP2 and MRPP3, form the mitochondrial ribonuclease P (mt-RNase P) complex that cleaves the 5′ ends of mt-tRNAs from polycistronic precursor transcripts. Additionally, a stable complex of MRPP1 and MRPP2 has m1R9 methyltransferase activity, which methylates mt-tRNAs at position 9 and is vital for folding mt-tRNAs into their correct tertiary structures. Analyses of fibroblasts from affected individuals harboring TRMT10C missense variants revealed decreased protein levels of MRPP1 and an increase in mt-RNA precursors indicative of impaired mt-RNA processing and defective mitochondrial protein synthesis. The pathogenicity of the detected variants—compound heterozygous c.542G>T (p.Arg181Leu) and c.814A>G (p.Thr272Ala) changes in subject 1 and a homozygous c.542G>T (p.Arg181Leu) variant in subject 2—was validated by the functional rescue of mt-RNA processing and mitochondrial protein synthesis defects after lentiviral transduction of wild-type TRMT10C. Our study suggests that these variants affect MRPP1 protein stability and mt-tRNA processing without affecting m1R9 methyltransferase activity, identifying mutations in TRMT10C as a cause of mitochondrial disease and highlighting the importance of RNA processing for correct mitochondrial function.
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85
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Aubee JI, Olu M, Thompson KM. The i6A37 tRNA modification is essential for proper decoding of UUX-Leucine codons during rpoS and iraP translation. RNA (NEW YORK, N.Y.) 2016; 22:729-742. [PMID: 26979278 PMCID: PMC4836647 DOI: 10.1261/rna.053165.115] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/05/2016] [Indexed: 06/05/2023]
Abstract
The translation of rpoS(σ(S)), the general stress/stationary phase sigma factor, is tightly regulated at the post-transcriptional level by several factors via mechanisms that are not clearly defined. One of these factors is MiaA, the enzyme necessary for the first step in theN(6)-isopentyl-2-thiomethyl adenosinemethyl adenosine 37 (ms(2)i(6)A37) tRNA modification. We tested the hypothesis that an elevated UUX-Leucine/total leucine codon ratio can be used to identify transcripts whose translation would be sensitive to loss of the MiaA-dependent modification. We identified iraPas another candidate MiaA-sensitive gene, based on the UUX-Leucine/total leucine codon ratio. AniraP-lacZ fusion was significantly decreased in the abse nce of MiaA, consistent with our predictive model. To determine the role of MiaA in UUX-Leucine decoding in rpoS and iraP, we measured β-galactosidase-specific activity of miaA(-)rpo Sandira P translational fusions upon overexpression of leucine tRNAs. We observed suppression of the MiaA effect on rpoS, and notira P, via overexpression of tRNA(LeuX)but not tRNA(LeuZ) We also tested the hypothesis that the MiaA requirement for rpoS and iraP translation is due to decoding of UUX-Leucine codons within the rpoS and iraP transcripts, respectively. We observed a partial suppression of the MiaA requirement for rpoS and iraP translational fusions containing one or both UUX-Leucine codons removed. Taken together, this suggests that MiaA is necessary for rpoS and iraP translation through proper decoding of UUX-Leucine codons and that rpoS and iraP mRNAs are both modification tunable transcripts (MoTTs) via the presence of the modification.
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Affiliation(s)
- Joseph I Aubee
- Department of Microbiology, College of Medicine, Howard University, Washington, DC 20059, USA
| | - Morenike Olu
- Department of Microbiology, College of Medicine, Howard University, Washington, DC 20059, USA Department of Biology, Howard University, Washington, DC 20059, USA
| | - Karl M Thompson
- Department of Microbiology, College of Medicine, Howard University, Washington, DC 20059, USA
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86
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Lamichhane TN, Arimbasseri AG, Rijal K, Iben JR, Wei FY, Tomizawa K, Maraia RJ. Lack of tRNA-i6A modification causes mitochondrial-like metabolic deficiency in S. pombe by limiting activity of cytosolic tRNATyr, not mito-tRNA. RNA (NEW YORK, N.Y.) 2016; 22:583-96. [PMID: 26857223 PMCID: PMC4793213 DOI: 10.1261/rna.054064.115] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/28/2015] [Indexed: 05/17/2023]
Abstract
tRNA-isopentenyl transferases (IPTases) are highly conserved enzymes that form isopentenyl-N(6)-A37 (i6A37) on subsets of tRNAs, enhancing their translation activity. Nuclear-encoded IPTases modify select cytosolic (cy-) and mitochondrial (mt-) tRNAs. Mutation in human IPTase, TRIT1, causes disease phenotypes characteristic of mitochondrial translation deficiency due to mt-tRNA dysfunction. Deletion of the Schizosaccharomyces pombe IPTase (tit1-Δ) causes slow growth in glycerol, as well as in rapamycin, an inhibitor of TOR kinase that maintains metabolic homeostasis. Schizosaccharomyces pombe IPTase modifies three different cy-tRNAs(Ser) as well as cy-tRNA(Tyr), cy-tRNA(Trp), and mt-tRNA(Trp). We show that lower ATP levels in tit1-Δ relative to tit1(+) cells are also more decreased by an inhibitor of oxidative phosphorylation, indicative of mitochondrial dysfunction. Here we asked if the tit1-Δ phenotypes are due to hypomodification of cy-tRNA or mt-tRNA. A cytosol-specific IPTase that modifies cy-tRNA, but not mt-tRNA, fully rescues the tit1-Δ phenotypes. Moreover, overexpression of cy-tRNAs also rescues the phenotypes, and cy-tRNA(Tyr) alone substantially does so. Bioinformatics indicate that cy-tRNA(Tyr) is most limiting for codon demand in tit1-Δ cells and that the cytosolic mRNAs most loaded with Tyr codons encode carbon metabolilizing enzymes, many of which are known to localize to mitochondria. Thus, S. pombe i6A37 hypomodification-associated metabolic deficiency results from hypoactivity of cy-tRNA, mostly tRNA(Tyr), and unlike human TRIT1-deficiency does not impair mitochondrial translation due to mt-tRNA hypomodification. We discuss species-specific aspects of i6A37. Specifically relevant to mitochondria, we show that its hypermodified version, ms2i6A37 (2-methylthiolated), which occurs on certain mammalian mt-tRNAs (but not cy-tRNAs), is not found in yeast.
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Affiliation(s)
- Tek N Lamichhane
- Section on Molecular and Cell Biology, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Aneeshkumar G Arimbasseri
- Section on Molecular and Cell Biology, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Keshab Rijal
- Section on Molecular and Cell Biology, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - James R Iben
- Molecular Genetics Laboratory, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Fan Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, 860-0862 Kumamoto, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, 860-0862 Kumamoto, Japan
| | - Richard J Maraia
- Section on Molecular and Cell Biology, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA Commissioned Corps, US Public Health Service, Rockville, Maryland 20016, USA
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87
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Oláhová M, Hardy SA, Hall J, Yarham JW, Haack TB, Wilson WC, Alston CL, He L, Aznauryan E, Brown RM, Brown GK, Morris AAM, Mundy H, Broomfield A, Barbosa IA, Simpson MA, Deshpande C, Moeslinger D, Koch J, Stettner GM, Bonnen PE, Prokisch H, Lightowlers RN, McFarland R, Chrzanowska-Lightowlers ZMA, Taylor RW. LRPPRC mutations cause early-onset multisystem mitochondrial disease outside of the French-Canadian population. Brain 2015; 138:3503-19. [PMID: 26510951 PMCID: PMC4655343 DOI: 10.1093/brain/awv291] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/11/2015] [Indexed: 12/27/2022] Open
Abstract
The French-Canadian variant of COX-deficient Leigh syndrome (LSFC) is unique to Québec and caused by a founder mutation in the LRPPRC gene. Using whole exome sequencing, Oláhová et al. identify mutations in this gene associated with multisystem mitochondrial disease and early-onset neurodevelopmental problems in ten patients from different ethnic backgrounds. Mitochondrial Complex IV [cytochrome c oxidase (COX)] deficiency is one of the most common respiratory chain defects in humans. The clinical phenotypes associated with COX deficiency include liver disease, cardiomyopathy and Leigh syndrome, a neurodegenerative disorder characterized by bilateral high signal lesions in the brainstem and basal ganglia. COX deficiency can result from mutations affecting many different mitochondrial proteins. The French-Canadian variant of COX-deficient Leigh syndrome is unique to the Saguenay-Lac-Saint-Jean region of Québec and is caused by a founder mutation in the LRPPRC gene. This encodes the leucine-rich pentatricopeptide repeat domain protein (LRPPRC), which is involved in post-transcriptional regulation of mitochondrial gene expression. Here, we present the clinical and molecular characterization of novel, recessive LRPPRC gene mutations, identified using whole exome and candidate gene sequencing. The 10 patients come from seven unrelated families of UK-Caucasian, UK-Pakistani, UK-Indian, Turkish and Iraqi origin. They resemble the French-Canadian Leigh syndrome patients in having intermittent severe lactic acidosis and early-onset neurodevelopmental problems with episodes of deterioration. In addition, many of our patients have had neonatal cardiomyopathy or congenital malformations, most commonly affecting the heart and the brain. All patients who were tested had isolated COX deficiency in skeletal muscle. Functional characterization of patients’ fibroblasts and skeletal muscle homogenates showed decreased levels of mutant LRPPRC protein and impaired Complex IV enzyme activity, associated with abnormal COX assembly and reduced steady-state levels of numerous oxidative phosphorylation subunits. We also identified a Complex I assembly defect in skeletal muscle, indicating different roles for LRPPRC in post-transcriptional regulation of mitochondrial mRNAs between tissues. Patient fibroblasts showed decreased steady-state levels of mitochondrial mRNAs, although the length of poly(A) tails of mitochondrial transcripts were unaffected. Our study identifies LRPPRC as an important disease-causing gene in an early-onset, multisystem and neurological mitochondrial disease, which should be considered as a cause of COX deficiency even in patients originating outside of the French-Canadian population.
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Affiliation(s)
- Monika Oláhová
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Steven A Hardy
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Julie Hall
- 2 Department of Neuroradiology, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 3BZ, UK
| | - John W Yarham
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Tobias B Haack
- 3 Institute of Human Genetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany 4 Institut für Humangenetik, Technische Universität München, Arcisstrasse 21, 80333 Munich, Germany
| | - William C Wilson
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Charlotte L Alston
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Langping He
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Erik Aznauryan
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Ruth M Brown
- 5 Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Garry K Brown
- 5 Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Andrew A M Morris
- 6 Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL, UK
| | - Helen Mundy
- 7 Centre for Inherited Metabolic Disease, Evelina Children's Hospital, Guy's and St. Thomas' NHS Foundation Trust, London, SE1 7EH, UK
| | - Alex Broomfield
- 6 Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Central Manchester University Hospitals NHS Foundation Trust, Manchester, M13 9WL, UK
| | - Ines A Barbosa
- 8 Division of Genetics and Molecular Medicine, King's College London School of Medicine, London, SE1 9RY, UK
| | - Michael A Simpson
- 8 Division of Genetics and Molecular Medicine, King's College London School of Medicine, London, SE1 9RY, UK
| | - Charu Deshpande
- 9 Department of Genetics, Guy's and St. Thomas' NHS Foundation Trust, London, SE1 9RT, UK
| | - Dorothea Moeslinger
- 10 Department of Paediatrics, University Children's Hospital, A-1090 Vienna, Austria
| | - Johannes Koch
- 11 Department of Paediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria
| | - Georg M Stettner
- 12 Department of Paediatric Neurology, Georg August University, 37075 Göttingen, Germany
| | - Penelope E Bonnen
- 13 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Holger Prokisch
- 3 Institute of Human Genetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany 4 Institut für Humangenetik, Technische Universität München, Arcisstrasse 21, 80333 Munich, Germany
| | - Robert N Lightowlers
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | | | - Robert W Taylor
- 1 Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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88
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Shaheen R, Abdel-Salam GMH, Guy MP, Alomar R, Abdel-Hamid MS, Afifi HH, Ismail SI, Emam BA, Phizicky EM, Alkuraya FS. Mutation in WDR4 impairs tRNA m(7)G46 methylation and causes a distinct form of microcephalic primordial dwarfism. Genome Biol 2015; 16:210. [PMID: 26416026 PMCID: PMC4587777 DOI: 10.1186/s13059-015-0779-x] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/14/2015] [Indexed: 04/13/2023] Open
Abstract
Background Primordial dwarfism is a state of extreme prenatal and postnatal growth deficiency, and is characterized by marked clinical and genetic heterogeneity. Results Two presumably unrelated consanguineous families presented with an apparently novel form of primordial dwarfism in which severe growth deficiency is accompanied by distinct facial dysmorphism, brain malformation (microcephaly, agenesis of corpus callosum, and simplified gyration), and severe encephalopathy with seizures. Combined autozygome/exome analysis revealed a novel missense mutation in WDR4 as the likely causal variant. WDR4 is the human ortholog of the yeast Trm82, an essential component of the Trm8/Trm82 holoenzyme that effects a highly conserved and specific (m7G46) methylation of tRNA. The human mutation and the corresponding yeast mutation result in a significant reduction of m7G46 methylation of specific tRNA species, which provides a potential mechanism for primordial dwarfism associated with this lesion, since reduced m7G46 modification causes a growth deficiency phenotype in yeast. Conclusion Our study expands the number of biological pathways underlying primordial dwarfism and adds to a growing list of human diseases linked to abnormal tRNA modification. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0779-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ranad Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Ghada M H Abdel-Salam
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Michael P Guy
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.,Current address: Department of Chemistry, Northern Kentucky University, Highland Heights, KY, USA
| | - Rana Alomar
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mohamed S Abdel-Hamid
- Medical Molecular Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Hanan H Afifi
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Samira I Ismail
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Bayoumi A Emam
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. .,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
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89
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Guy MP, Shaw M, Weiner CL, Hobson L, Stark Z, Rose K, Kalscheuer VM, Gecz J, Phizicky EM. Defects in tRNA Anticodon Loop 2'-O-Methylation Are Implicated in Nonsyndromic X-Linked Intellectual Disability due to Mutations in FTSJ1. Hum Mutat 2015; 36:1176-87. [PMID: 26310293 DOI: 10.1002/humu.22897] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/12/2015] [Indexed: 01/18/2023]
Abstract
tRNA modifications are crucial for efficient and accurate protein synthesis, and modification defects are frequently associated with disease. Yeast trm7Δ mutants grow poorly due to lack of 2'-O-methylated C32 (Cm32 ) and Gm34 on tRNA(Phe) , catalyzed by Trm7-Trm732 and Trm7-Trm734, respectively, which in turn results in loss of wybutosine at G37 . Mutations in human FTSJ1, the likely TRM7 homolog, cause nonsyndromic X-linked intellectual disability (NSXLID), but the role of FTSJ1 in tRNA modification is unknown. Here, we report that tRNA(Phe) from two genetically independent cell lines of NSXLID patients with loss-of-function FTSJ1 mutations nearly completely lacks Cm32 and Gm34 , and has reduced peroxywybutosine (o2yW37 ). Additionally, tRNA(Phe) from an NSXLID patient with a novel FTSJ1-p.A26P missense allele specifically lacks Gm34 , but has normal levels of Cm32 and o2yW37 . tRNA(Phe) from the corresponding Saccharomyces cerevisiae trm7-A26P mutant also specifically lacks Gm34 , and the reduced Gm34 is not due to weaker Trm734 binding. These results directly link defective 2'-O-methylation of the tRNA anticodon loop to FTSJ1 mutations, suggest that the modification defects cause NSXLID, and may implicate Gm34 of tRNA(Phe) as the critical modification. These results also underscore the widespread conservation of the circuitry for Trm7-dependent anticodon loop modification of eukaryotic tRNA(Phe) .
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Affiliation(s)
- Michael P Guy
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, New York, 14642
| | - Marie Shaw
- Robinson Research Institute, The University of Adelaide, Adelaide, South Australia 5000, Australia.,School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, South Australia 5000, Australia
| | - Catherine L Weiner
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, New York, 14642
| | - Lynne Hobson
- SA Pathology, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Zornitza Stark
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, Victoria 3052, Australia
| | - Katherine Rose
- Monash Health, Special Medicine Centre, Monash Medical Centre, Clayton, Victoria 3168, Australia
| | - Vera M Kalscheuer
- Department Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin D14195, Germany
| | - Jozef Gecz
- Robinson Research Institute, The University of Adelaide, Adelaide, South Australia 5000, Australia.,School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, South Australia 5000, Australia
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine, Rochester, New York, 14642
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90
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Powell C, Kopajtich R, D’Souza AR, Rorbach J, Kremer L, Husain R, Dallabona C, Donnini C, Alston C, Griffin H, Pyle A, Chinnery P, Strom T, Meitinger T, Rodenburg R, Schottmann G, Schuelke M, Romain N, Haller R, Ferrero I, Haack T, Taylor R, Prokisch H, Minczuk M. TRMT5 Mutations Cause a Defect in Post-transcriptional Modification of Mitochondrial tRNA Associated with Multiple Respiratory-Chain Deficiencies. Am J Hum Genet 2015; 97:319-28. [PMID: 26189817 PMCID: PMC4573257 DOI: 10.1016/j.ajhg.2015.06.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/16/2015] [Indexed: 10/29/2022] Open
Abstract
Deficiencies in respiratory-chain complexes lead to a variety of clinical phenotypes resulting from inadequate energy production by the mitochondrial oxidative phosphorylation system. Defective expression of mtDNA-encoded genes, caused by mutations in either the mitochondrial or nuclear genome, represents a rapidly growing group of human disorders. By whole-exome sequencing, we identified two unrelated individuals carrying compound heterozygous variants in TRMT5 (tRNA methyltransferase 5). TRMT5 encodes a mitochondrial protein with strong homology to members of the class I-like methyltransferase superfamily. Both affected individuals presented with lactic acidosis and evidence of multiple mitochondrial respiratory-chain-complex deficiencies in skeletal muscle, although the clinical presentation of the two affected subjects was remarkably different; one presented in childhood with failure to thrive and hypertrophic cardiomyopathy, and the other was an adult with a life-long history of exercise intolerance. Mutations in TRMT5 were associated with the hypomodification of a guanosine residue at position 37 (G37) of mitochondrial tRNA; this hypomodification was particularly prominent in skeletal muscle. Deficiency of the G37 modification was also detected in human cells subjected to TRMT5 RNAi. The pathogenicity of the detected variants was further confirmed in a heterologous yeast model and by the rescue of the molecular phenotype after re-expression of wild-type TRMT5 cDNA in cells derived from the affected individuals. Our study highlights the importance of post-transcriptional modification of mitochondrial tRNAs for faithful mitochondrial function.
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91
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Mayr JA, Haack TB, Freisinger P, Karall D, Makowski C, Koch J, Feichtinger RG, Zimmermann FA, Rolinski B, Ahting U, Meitinger T, Prokisch H, Sperl W. Spectrum of combined respiratory chain defects. J Inherit Metab Dis 2015; 38:629-40. [PMID: 25778941 PMCID: PMC4493854 DOI: 10.1007/s10545-015-9831-y] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 01/22/2023]
Abstract
Inherited disorders of mitochondrial energy metabolism form a large and heterogeneous group of metabolic diseases. More than 250 gene defects have been reported to date and this number continues to grow. Mitochondrial diseases can be grouped into (1) disorders of oxidative phosphorylation (OXPHOS) subunits and their assembly factors, (2) defects of mitochondrial DNA, RNA and protein synthesis, (3) defects in the substrate-generating upstream reactions of OXPHOS, (4) defects in relevant cofactors and (5) defects in mitochondrial homeostasis. Deficiency of more than one respiratory chain enzyme is a common finding. Combined defects are found in 49 % of the known disease-causing genes of mitochondrial energy metabolism and in 57 % of patients with OXPHOS defects identified in our diagnostic centre. Combined defects of complexes I, III, IV and V are typically due to deficiency of mitochondrial DNA replication, RNA metabolism or translation. Defects in cofactors can result in combined defects of various combinations, and defects of mitochondrial homeostasis can result in a generalised decrease of all OXPHOS enzymes. Noteworthy, identification of combined defects can be complicated by different degrees of severity of each affected enzyme. Furthermore, even defects of single respiratory chain enzymes can result in combined defects due to aberrant formation of respiratory chain supercomplexes. Combined OXPHOS defects have a great variety of clinical manifestations in terms of onset, course severity and tissue involvement. They can present as classical encephalomyopathy but also with hepatopathy, nephropathy, haematologic findings and Perrault syndrome in a subset of disorders.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University, SALK Salzburg, Salzburg, 5020, Austria,
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92
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Van Haute L, Pearce SF, Powell CA, D’Souza AR, Nicholls TJ, Minczuk M. Mitochondrial transcript maturation and its disorders. J Inherit Metab Dis 2015; 38:655-80. [PMID: 26016801 PMCID: PMC4493943 DOI: 10.1007/s10545-015-9859-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/27/2015] [Accepted: 04/29/2015] [Indexed: 11/03/2022]
Abstract
Mitochondrial respiratory chain deficiencies exhibit a wide spectrum of clinical presentations owing to defective mitochondrial energy production through oxidative phosphorylation. These defects can be caused by either mutations in the mitochondrial DNA (mtDNA) or mutations in nuclear genes coding for mitochondrially-targeted proteins. The underlying pathomechanisms can affect numerous pathways involved in mitochondrial biology including expression of mtDNA-encoded genes. Expression of the mitochondrial genes is extensively regulated at the post-transcriptional stage and entails nucleolytic cleavage of precursor RNAs, RNA nucleotide modifications, RNA polyadenylation, RNA quality and stability control. These processes ensure proper mitochondrial RNA (mtRNA) function, and are regulated by dedicated, nuclear-encoded enzymes. Recent growing evidence suggests that mutations in these nuclear genes, leading to incorrect maturation of RNAs, are a cause of human mitochondrial disease. Additionally, mutations in mtDNA-encoded genes may also affect RNA maturation and are frequently associated with human disease. We review the current knowledge on a subset of nuclear-encoded genes coding for proteins involved in mitochondrial RNA maturation, for which genetic variants impacting upon mitochondrial pathophysiology have been reported. Also, primary pathological mtDNA mutations with recognised effects upon RNA processing are described.
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Affiliation(s)
| | - Sarah F. Pearce
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | | | - Aaron R. D’Souza
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | - Thomas J. Nicholls
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
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93
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Wortmann SB, Koolen DA, Smeitink JA, van den Heuvel L, Rodenburg RJ. Whole exome sequencing of suspected mitochondrial patients in clinical practice. J Inherit Metab Dis 2015; 38:437-43. [PMID: 25735936 PMCID: PMC4432107 DOI: 10.1007/s10545-015-9823-y] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 12/04/2014] [Accepted: 02/06/2015] [Indexed: 11/25/2022]
Abstract
Mitochondrial disorders are characterized by a broad clinical spectrum. Identical clinical signs and symptoms can be caused by mutations in different mitochondrial or nuclear genes. Vice versa, the same mutation can lead to different phenotypes. Genetic syndromes and neuromuscular disorders mimicking mitochondrial disorders further complicate the diagnostic process. Whole exome sequencing (WES) is the state of the art next generation sequencing technique to identify genetic defects in mitochondrial disorders. Until recently it has mainly been used as a research tool. In this study, the use of WES in routine diagnostics is described. The WES data of 109 patients, referred under the suspicion of a mitochondrial disorder, were examined in two steps. First, the data were filtered using a virtual gene panel of genes known to be associated with mitochondrial disease. If negative, the entire exome was examined. A molecular diagnosis was achieved in 39% of the heterogeneous cohort, and in 57% of the subgroup of 42 patients with the highest suspicion for a mitochondrial disease. In addition to mutations in genes known to be associated with mitochondrial disorders (e.g. TUFM, MTFMT, FBXL4), in the subgroup of patients with the lowest suspicion for a mitochondrial disorder we found mutations in several genes associated with neuromuscular disorders (e.g. SEPN1, ACTA1) and genetic syndrome (e.g. SETBP1, ARID1B). Our results show that WES technology has been successfully implemented as a state-of-the-art, molecular diagnostic test for mitochondrial disorders as well as for the mimicking disorders in daily clinical practice. It also illustrates that clinical and biochemical phenotyping is essential for successful application of WES to diagnose individual patients.
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Affiliation(s)
- Saskia B. Wortmann
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - David A. Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan A. Smeitink
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lambert van den Heuvel
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
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94
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Powell CA, Nicholls TJ, Minczuk M. Nuclear-encoded factors involved in post-transcriptional processing and modification of mitochondrial tRNAs in human disease. Front Genet 2015; 6:79. [PMID: 25806043 PMCID: PMC4354410 DOI: 10.3389/fgene.2015.00079] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/16/2015] [Indexed: 11/29/2022] Open
Abstract
The human mitochondrial genome (mtDNA) encodes 22 tRNAs (mt-tRNAs) that are necessary for the intraorganellar translation of the 13 mtDNA-encoded subunits of the mitochondrial respiratory chain complexes. Maturation of mt-tRNAs involves 5′ and 3′ nucleolytic excision from precursor RNAs, as well as extensive post-transcriptional modifications. Recent data suggest that over 7% of all mt-tRNA residues in mammals undergo post-transcriptional modification, with over 30 different modified mt-tRNA positions so far described. These processing and modification steps are necessary for proper mt-tRNA function, and are performed by dedicated, nuclear-encoded enzymes. Recent growing evidence suggests that mutations in these nuclear genes (nDNA), leading to incorrect maturation of mt-tRNAs, are a cause of human mitochondrial disease. Furthermore, mtDNA mutations in mt-tRNA genes, which may also affect mt-tRNA function, processing, and modification, are also frequently associated with human disease. In theory, all pathogenic mt-tRNA variants should be expected to affect only a single process, which is mitochondrial translation, albeit to various extents. However, the clinical manifestations of mitochondrial disorders linked to mutations in mt-tRNAs are extremely heterogeneous, ranging from defects of a single tissue to complex multisystem disorders. This review focuses on the current knowledge of nDNA coding for proteins involved in mt-tRNA maturation that have been linked to human mitochondrial pathologies. We further discuss the possibility that tissue specific regulation of mt-tRNA modifying enzymes could play an important role in the clinical heterogeneity observed for mitochondrial diseases caused by mutations in mt-tRNA genes.
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Affiliation(s)
- Christopher A Powell
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
| | - Thomas J Nicholls
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
| | - Michal Minczuk
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
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95
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Abstract
Protein synthesis is critically dependent on transfer (t)-RNAs, but the factors regulating tRNA function are poorly understood. In this issue of Cell Metabolism, Wei et al. (2015) show that Cdk5 regulatory subunit-associated protein-like-1 synchronizes mitochondrial and cytosolic translation in response to external stress, providing key insight into the pathogenesis of a common inherited mitochondrial disease.
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Affiliation(s)
- Rita Horvath
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Patrick F Chinnery
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK.
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96
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Sasarman F, Thiffault I, Weraarpachai W, Salomon S, Maftei C, Gauthier J, Ellazam B, Webb N, Antonicka H, Janer A, Brunel-Guitton C, Elpeleg O, Mitchell G, Shoubridge EA. The 3' addition of CCA to mitochondrial tRNASer(AGY) is specifically impaired in patients with mutations in the tRNA nucleotidyl transferase TRNT1. Hum Mol Genet 2015; 24:2841-7. [PMID: 25652405 DOI: 10.1093/hmg/ddv044] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 02/02/2015] [Indexed: 11/14/2022] Open
Abstract
Addition of the trinucleotide cytosine/cytosine/adenine (CCA) to the 3' end of transfer RNAs (tRNAs) is essential for translation and is catalyzed by the enzyme TRNT1 (tRNA nucleotidyl transferase), which functions in both the cytoplasm and mitochondria. Exome sequencing revealed TRNT1 mutations in two unrelated subjects with different clinical features. The first presented with acute lactic acidosis at 3 weeks of age and developed severe developmental delay, hypotonia, microcephaly, seizures, progressive cortical atrophy, neurosensorial deafness, sideroblastic anemia and renal Fanconi syndrome, dying at 21 months. The second presented at 3.5 years with gait ataxia, dysarthria, gross motor regression, hypotonia, ptosis and ophthalmoplegia and had abnormal signals in brainstem and dentate nucleus. In subject 1, muscle biopsy showed combined oxidative phosphorylation (OXPHOS) defects, but there was no OXPHOS deficiency in fibroblasts from either subject, despite a 10-fold-reduction in TRNT1 protein levels in fibroblasts of the first subject. Furthermore, in normal controls, TRNT1 protein levels are 10-fold lower in muscle than in fibroblasts. High resolution northern blots of subject fibroblast RNA suggested incomplete CCA addition to the non-canonical mitochondrial tRNA(Ser(AGY)), but no obvious qualitative differences in other mitochondrial or cytoplasmic tRNAs. Complete knockdown of TRNT1 in patient fibroblasts rendered mitochondrial tRNA(Ser(AGY)) undetectable, and markedly reduced mitochondrial translation, except polypeptides lacking Ser(AGY) codons. These data suggest that the clinical phenotypes associated with TRNT1 mutations are largely due to impaired mitochondrial translation, resulting from defective CCA addition to mitochondrial tRNA(Ser(AGY)), and that the severity of this biochemical phenotype determines the severity and tissue distribution of clinical features.
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Affiliation(s)
- Florin Sasarman
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada, Division of Medical Genetics, Department of Pediatrics, and
| | - Isabelle Thiffault
- Division of Medical Genetics, Department of Pediatrics, and Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO, USA and
| | - Woranontee Weraarpachai
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Steven Salomon
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | | | - Julie Gauthier
- Division of Medical Genetics, Department of Pediatrics, and
| | - Benjamin Ellazam
- Department of Pathology, CHU Sainte-Justine and Université de Montréal, Montreal, QC, Canada
| | - Neil Webb
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada, Division of Medical Genetics, Department of Pediatrics, and
| | - Hana Antonicka
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Alexandre Janer
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | | | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel
| | - Grant Mitchell
- Division of Medical Genetics, Department of Pediatrics, and
| | - Eric A Shoubridge
- Montreal Neurological Institute and Department of Human Genetics, McGill University, Montreal, QC, Canada,
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97
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Guy MP, Phizicky EM. Conservation of an intricate circuit for crucial modifications of the tRNAPhe anticodon loop in eukaryotes. RNA (NEW YORK, N.Y.) 2015; 21:61-74. [PMID: 25404562 PMCID: PMC4274638 DOI: 10.1261/rna.047639.114] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Post-transcriptional tRNA modifications are critical for efficient and accurate translation, and have multiple different roles. Lack of modifications often leads to different biological consequences in different organisms, and in humans is frequently associated with neurological disorders. We investigate here the conservation of a unique circuitry for anticodon loop modification required for healthy growth in the yeast Saccharomyces cerevisiae. S. cerevisiae Trm7 interacts separately with Trm732 and Trm734 to 2'-O-methylate three substrate tRNAs at anticodon loop residues C₃₂ and N₃₄, and these modifications are required for efficient wybutosine formation at m(1)G₃₇ of tRNA(Phe). Moreover, trm7Δ and trm732Δ trm734Δ mutants grow poorly due to lack of functional tRNA(Phe). It is unknown if this circuitry is conserved and important for tRNA(Phe) modification in other eukaryotes, but a likely human TRM7 ortholog is implicated in nonsyndromic X-linked intellectual disability. We find that the distantly related yeast Schizosaccharomyces pombe has retained this circuitry for anticodon loop modification, that S. pombe trm7Δ and trm734Δ mutants have more severe phenotypes than the S. cerevisiae mutants, and that tRNA(Phe) is the major biological target. Furthermore, we provide evidence that Trm7 and Trm732 function is widely conserved throughout eukaryotes, since human FTSJ1 and THADA, respectively, complement growth defects of S. cerevisiae trm7Δ and trm732Δ trm734Δ mutants by modifying C₃₂ of tRNA(Phe), each working with the corresponding S. cerevisiae partner protein. These results suggest widespread importance of 2'-O-methylation of the tRNA anticodon loop, implicate tRNA(Phe) as the crucial substrate, and suggest that this modification circuitry is important for human neuronal development.
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Affiliation(s)
- Michael P Guy
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
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98
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Mutations in GTPBP3 cause a mitochondrial translation defect associated with hypertrophic cardiomyopathy, lactic acidosis, and encephalopathy. Am J Hum Genet 2014; 95:708-20. [PMID: 25434004 DOI: 10.1016/j.ajhg.2014.10.017] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/29/2014] [Indexed: 11/22/2022] Open
Abstract
Respiratory chain deficiencies exhibit a wide variety of clinical phenotypes resulting from defective mitochondrial energy production through oxidative phosphorylation. These defects can be caused by either mutations in the mtDNA or mutations in nuclear genes coding for mitochondrial proteins. The underlying pathomechanisms can affect numerous pathways involved in mitochondrial physiology. By whole-exome and candidate gene sequencing, we identified 11 individuals from 9 families carrying compound heterozygous or homozygous mutations in GTPBP3, encoding the mitochondrial GTP-binding protein 3. Affected individuals from eight out of nine families presented with combined respiratory chain complex deficiencies in skeletal muscle. Mutations in GTPBP3 are associated with a severe mitochondrial translation defect, consistent with the predicted function of the protein in catalyzing the formation of 5-taurinomethyluridine (τm(5)U) in the anticodon wobble position of five mitochondrial tRNAs. All case subjects presented with lactic acidosis and nine developed hypertrophic cardiomyopathy. In contrast to individuals with mutations in MTO1, the protein product of which is predicted to participate in the generation of the same modification, most individuals with GTPBP3 mutations developed neurological symptoms and MRI involvement of thalamus, putamen, and brainstem resembling Leigh syndrome. Our study of a mitochondrial translation disorder points toward the importance of posttranscriptional modification of mitochondrial tRNAs for proper mitochondrial function.
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99
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Rijal K, Maraia RJ, Arimbasseri AG. A methods review on use of nonsense suppression to study 3' end formation and other aspects of tRNA biogenesis. Gene 2014; 556:35-50. [PMID: 25447915 DOI: 10.1016/j.gene.2014.11.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 12/26/2022]
Abstract
Suppressor tRNAs bear anticodon mutations that allow them to decode premature stop codons in metabolic marker gene mRNAs, that can be used as in vivo reporters of functional tRNA biogenesis. Here, we review key components of a suppressor tRNA system specific to Schizosaccharomyces pombe and its adaptations for use to study specific steps in tRNA biogenesis. Eukaryotic tRNA biogenesis begins with transcription initiation by RNA polymerase (pol) III. The nascent pre-tRNAs must undergo folding, 5' and 3' processing to remove the leader and trailer, nuclear export, and splicing if applicable, while multiple complex chemical modifications occur throughout the process. We review evidence that precursor-tRNA processing begins with transcription termination at the oligo(T) terminator element, which forms a 3' oligo(U) tract on the nascent RNA, a sequence-specific binding site for the RNA chaperone, La protein. The processing pathway bifurcates depending on a poorly understood property of pol III termination that determines the 3' oligo(U) length and therefore the affinity for La. We thus review the pol III termination process and the factors involved including advances using gene-specific random mutagenesis by dNTP analogs that identify key residues important for transcription termination in certain pol III subunits. The review ends with a 'technical approaches' section that includes a parts lists of suppressor-tRNA alleles, strains and plasmids, and graphic examples of its diverse uses.
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Affiliation(s)
- Keshab Rijal
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Richard J Maraia
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Aneeshkumar G Arimbasseri
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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100
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Smaldino PJ, Read DF, Pratt-Hyatt M, Hopper AK, Engelke DR. The cytoplasmic and nuclear populations of the eukaryote tRNA-isopentenyl transferase have distinct functions with implications in human cancer. Gene 2014; 556:13-8. [PMID: 25261850 DOI: 10.1016/j.gene.2014.09.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 12/29/2022]
Abstract
Mod5 is the yeast tRNA isopentenyl transferase, an enzyme that is conserved from bacteria to humans. Mod5 is primarily cytoplasmic where it modifies the A37 position of a few tRNAs, and the yeast enzyme has been shown capable of forming heritable, amyloid-like aggregates that confer a selective advantage in the presence of specific antifungal agents. A subpopulation of Mod5 is also found associated with nuclear tRNA genes, where it contributes tRNA-gene mediated (tgm) silencing of local transcription by RNA polymerase II. The tgm-silencing function of Mod5 has been observed in yeast and a Mod5-deletion in yeast can be complemented by the plant and human tRNA isopentenyl transferases, but not the bacterial enzymes, possibly due to the lack of an extended C-terminal domain found in eukaryotes. In light of this additional nuclear role for Mod5 we discuss the proposed role of the human homologue of Mod5, TRIT1, as a tumor suppressor protein.
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Affiliation(s)
- P J Smaldino
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
| | - D F Read
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - M Pratt-Hyatt
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; The Great Plains Laboratory, 11813W. 77th St. Lenexa KS 66214, USA
| | - A K Hopper
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - D R Engelke
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
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