51
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Charging the code - tRNA modification complexes. Curr Opin Struct Biol 2019; 55:138-146. [PMID: 31102979 DOI: 10.1016/j.sbi.2019.03.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 03/08/2019] [Indexed: 02/06/2023]
Abstract
All types of cellular RNAs are post-transcriptionally modified, constituting the so called 'epitranscriptome'. In particular, tRNAs and their anticodon stem loops represent major modification hotspots. The attachment of small chemical groups at the heart of the ribosomal decoding machinery can directly affect translational rates, reading frame maintenance, co-translational folding dynamics and overall proteome stability. The variety of tRNA modification patterns is driven by the activity of specialized tRNA modifiers and large modification complexes. Notably, the absence or dysfunction of these cellular machines is correlated with several human pathophysiologies. In this review, we aim to highlight the most recent scientific progress and summarize currently available structural information of the most prominent eukaryotic tRNA modifiers.
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52
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Dixit S, Henderson JC, Alfonzo JD. Multi-Substrate Specificity and the Evolutionary Basis for Interdependence in tRNA Editing and Methylation Enzymes. Front Genet 2019; 10:104. [PMID: 30838029 PMCID: PMC6382703 DOI: 10.3389/fgene.2019.00104] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/30/2019] [Indexed: 12/12/2022] Open
Abstract
Among tRNA modification enzymes there is a correlation between specificity for multiple tRNA substrates and heteromultimerization. In general, enzymes that modify a conserved residue in different tRNA sequences adopt a heterodimeric structure. Presumably, such changes in the oligomeric state of enzymes, to gain multi-substrate recognition, are driven by the need to accommodate and catalyze a particular reaction in different substrates while maintaining high specificity. This review focuses on two classes of enzymes where the case for multimerization as a way to diversify molecular recognition can be made. We will highlight several new themes with tRNA methyltransferases and will also discuss recent findings with tRNA editing deaminases. These topics will be discussed in the context of several mechanisms by which heterodimerization may have been achieved during evolution and how these mechanisms might impact modifications in different systems.
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Affiliation(s)
| | | | - Juan D. Alfonzo
- Department of Microbiology, The Ohio State Biochemistry Program, The Center for RNA Biology, The Ohio State University, Columbus, OH, United States
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53
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Han L, Phizicky EM. A rationale for tRNA modification circuits in the anticodon loop. RNA (NEW YORK, N.Y.) 2018; 24:1277-1284. [PMID: 30026310 PMCID: PMC6140457 DOI: 10.1261/rna.067736.118] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The numerous post-transcriptional modifications of tRNA play a crucial role in tRNA function. While most modifications are introduced to tRNA independently, several sets of modifications are found to be interconnected such that the presence of one set of modifications drives the formation of another modification. The vast majority of these modification circuits are found in the anticodon loop (ACL) region where the largest variety and highest density of modifications occur compared to the other parts of the tRNA and where there is relatively limited sequence and structural information. We speculate here that the modification circuits in the ACL region arise to enhance enzyme modification specificity by direct or indirect use of the first modification in the circuit as an additional recognition element for the second modification. We also describe the five well-studied modification circuits in the ACL, and outline possible mechanisms by which they may act. The prevalence of these modification circuits in the ACL and the phylogenetic conservation of some of them suggest that a number of other modification circuits will be found in this region in different organisms.
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Affiliation(s)
- Lu Han
- 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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54
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Zimmerman SM, Kon Y, Hauke AC, Ruiz BY, Fields S, Phizicky EM. Conditional accumulation of toxic tRNAs to cause amino acid misincorporation. Nucleic Acids Res 2018; 46:7831-7843. [PMID: 30007351 PMCID: PMC6125640 DOI: 10.1093/nar/gky623] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/22/2018] [Accepted: 07/01/2018] [Indexed: 12/16/2022] Open
Abstract
To develop a system for conditional amino acid misincorporation, we engineered tRNAs in the yeast Saccharomyces cerevisiae to be substrates of the rapid tRNA decay (RTD) pathway, such that they accumulate when RTD is turned off. We used this system to test the effects on growth of a library of tRNASer variants with all possible anticodons, and show that many are lethal when RTD is inhibited and the tRNA accumulates. Using mass spectrometry, we measured serine misincorporation in yeast containing each of six tRNA variants, and for five of them identified hundreds of peptides with serine substitutions at the targeted amino acid sites. Unexpectedly, we found that there is not a simple correlation between toxicity and the level of serine misincorporation; in particular, high levels of serine misincorporation can occur at cysteine residues without obvious growth defects. We also showed that toxic tRNAs can be used as a tool to identify sequence variants that reduce tRNA function. Finally, we generalized this method to another tRNA species, and generated conditionally toxic tRNATyr variants in a similar manner. This method should facilitate the study of tRNA biology and provide a tool to probe the effects of amino acid misincorporation on cellular physiology.
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Affiliation(s)
| | - Yoshiko Kon
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY 14642, USA
| | - Alayna C Hauke
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY 14642, USA
| | - Bianca Y Ruiz
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Stanley Fields
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Eric M Phizicky
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY 14642, USA
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55
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Kadumuri RV, Janga SC. Epitranscriptomic Code and Its Alterations in Human Disease. Trends Mol Med 2018; 24:886-903. [PMID: 30120023 DOI: 10.1016/j.molmed.2018.07.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 02/07/2023]
Abstract
Innovations in epitranscriptomics have resulted in the identification of more than 160 RNA modifications to date. These developments, together with the recent discovery of writers, readers, and erasers of modifications occurring across a wide range of RNAs and tissue types, have led to a surge in integrative approaches for transcriptome-wide mapping of modifications and protein-RNA interaction profiles of epitranscriptome players. RNA modification maps and crosstalk between them have begun to elucidate the role of modifications as signaling switches, entertaining the notion of an epitranscriptomic code as a driver of the post-transcriptional fate of RNA. Emerging single-molecule sequencing technologies and development of antibodies specific to various RNA modifications could enable charting of transcript-specific epitranscriptomic marks across cell types and their alterations in disease.
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Affiliation(s)
- Rajashekar Varma Kadumuri
- Department of BioHealth Informatics, School of Informatics and Computing, Walker Plaza Building, Indiana University-Purdue University Indianapolis, 719 Indiana Avenue, Suite 319, Indianapolis, IN 46202, USA
| | - Sarath Chandra Janga
- Department of BioHealth Informatics, School of Informatics and Computing, Walker Plaza Building, Indiana University-Purdue University Indianapolis, 719 Indiana Avenue, Suite 319, Indianapolis, IN 46202, USA; Department of Medical and Molecular Genetics, Medical Research and Library Building, Indiana University School of Medicine, 975 West Walnut Street, Indianapolis, IN 46202, USA; Centre for Computational Biology and Bioinformatics, 5021 Health Information and Translational Sciences, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, IN 46202, USA.
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56
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McKenney KM, Rubio MAT, Alfonzo JD. Binding synergy as an essential step for tRNA editing and modification enzyme codependence in Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2018; 24:56-66. [PMID: 29042505 PMCID: PMC5733570 DOI: 10.1261/rna.062893.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 10/02/2017] [Indexed: 05/10/2023]
Abstract
Transfer RNAs acquire a variety of naturally occurring chemical modifications during their maturation; these fine-tune their structure and decoding properties in a manner critical for protein synthesis. We recently reported that in the eukaryotic parasite, Trypanosoma brucei, a methylation and deamination event are unexpectedly interconnected, whereby the tRNA adenosine deaminase (TbADAT2/3) and the 3-methylcytosine methyltransferase (TbTrm140) strictly rely on each other for activity, leading to formation of m3C and m3U at position 32 in several tRNAs. Still however, it is not clear why these two enzymes, which work independently in other systems, are strictly codependent in T. brucei Here, we show that these enzymes exhibit binding synergism, or a mutual increase in binding affinity, that is more than the sum of the parts, when added together in a reaction. Although these enzymes interact directly with each other, tRNA binding assays using enzyme variants mutated in critical binding and catalytic sites indicate that the observed binding synergy stems from contributions from tRNA-binding domains distal to their active sites. These results provide a rationale for the known interactions of these proteins, while also speaking to the modulation of substrate specificity between seemingly unrelated enzymes. This information should be of value in furthering our understanding of how tRNA modification enzymes act together to regulate gene expression at the post-transcriptional level and provide a basis for the interdependence of such activities.
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Affiliation(s)
- Katherine M McKenney
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
| | - Mary Anne T Rubio
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Juan D Alfonzo
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
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57
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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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58
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Mattijssen S, Arimbasseri AG, Iben JR, Gaidamakov S, Lee J, Hafner M, Maraia RJ. LARP4 mRNA codon-tRNA match contributes to LARP4 activity for ribosomal protein mRNA poly(A) tail length protection. eLife 2017; 6:e28889. [PMID: 28895529 PMCID: PMC5626478 DOI: 10.7554/elife.28889] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/05/2017] [Indexed: 12/12/2022] Open
Abstract
Messenger RNA function is controlled by the 3' poly(A) tail (PAT) and poly(A)-binding protein (PABP). La-related protein-4 (LARP4) binds poly(A) and PABP. LARP4 mRNA contains a translation-dependent, coding region determinant (CRD) of instability that limits its expression. Although the CRD comprises <10% of LARP4 codons, the mRNA levels vary >20 fold with synonymous CRD substitutions that accommodate tRNA dynamics. Separately, overexpression of the most limiting tRNA increases LARP4 levels and reveals its functional activity, net lengthening of the PATs of heterologous mRNAs with concomitant stabilization, including ribosomal protein (RP) mRNAs. Genetic deletion of cellular LARP4 decreases PAT length and RPmRNA stability. This LARP4 activity requires its PABP-interaction domain and the RNA-binding module which we show is sensitive to poly(A) 3'-termini, consistent with protection from deadenylation. The results indicate that LARP4 is a posttranscriptional regulator of ribosomal protein production in mammalian cells and suggest that this activity can be controlled by tRNA levels.
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Affiliation(s)
- Sandy Mattijssen
- Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaUnited States
| | | | - James R Iben
- Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaUnited States
| | - Sergei Gaidamakov
- Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaUnited States
| | - Joowon Lee
- Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaUnited States
| | - Markus Hafner
- National Institute of Arthritis and Musculoskeletal and Skin DiseasesNational Institutes of HealthBethesdaUnited States
| | - Richard J Maraia
- Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaUnited States
- Commissioned CorpsUS Public Health ServiceBethesdaUnited Staes
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59
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Gogakos T, Brown M, Garzia A, Meyer C, Hafner M, Tuschl T. Characterizing Expression and Processing of Precursor and Mature Human tRNAs by Hydro-tRNAseq and PAR-CLIP. Cell Rep 2017; 20:1463-1475. [PMID: 28793268 PMCID: PMC5564215 DOI: 10.1016/j.celrep.2017.07.029] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/15/2017] [Accepted: 07/13/2017] [Indexed: 12/20/2022] Open
Abstract
The participation of tRNAs in fundamental aspects of biology and disease necessitates an accurate, experimentally confirmed annotation of tRNA genes and curation of tRNA sequences. This has been challenging because RNA secondary structure, nucleotide modifications, and tRNA gene multiplicity complicate sequencing and mapping efforts. To address these issues, we developed hydro-tRNAseq, a method based on partial alkaline RNA hydrolysis that generates fragments amenable for sequencing. To identify transcribed tRNA genes, we further complemented this approach with photoactivatable crosslinking and immunoprecipitation (PAR-CLIP) of SSB/La, a conserved protein involved in pre-tRNA processing. Our results show that approximately half of all predicted tRNA genes are transcribed in human cells. We also report nucleotide modification sites and their order of introduction, and we identify tRNA leaders, trailers, and introns. By using complementary sequencing-based methodologies, we present a human tRNA atlas and determine expression levels of mature and processing intermediates of tRNAs in human cells.
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Affiliation(s)
- Tasos Gogakos
- Howard Hughes Medical Institute and Laboratory for RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10065, USA
| | - Miguel Brown
- Howard Hughes Medical Institute and Laboratory for RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10065, USA
| | - Aitor Garzia
- Howard Hughes Medical Institute and Laboratory for RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10065, USA
| | - Cindy Meyer
- Howard Hughes Medical Institute and Laboratory for RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10065, USA
| | - Markus Hafner
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute for Arthritis and Musculoskeletal and Skin Diseases, 50 South Drive, MSC 8024, Bethesda, MD 20892, USA
| | - Thomas Tuschl
- Howard Hughes Medical Institute and Laboratory for RNA Molecular Biology, The Rockefeller University, 1230 York Avenue, Box 186, New York, NY 10065, USA.
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60
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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: 89] [Impact Index Per Article: 12.7] [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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61
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Xu L, Liu X, Sheng N, Oo KS, Liang J, Chionh YH, Xu J, Ye F, Gao YG, Dedon PC, Fu XY. Three distinct 3-methylcytidine (m 3C) methyltransferases modify tRNA and mRNA in mice and humans. J Biol Chem 2017; 292:14695-14703. [PMID: 28655767 DOI: 10.1074/jbc.m117.798298] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/23/2017] [Indexed: 01/05/2023] Open
Abstract
Chemical RNA modifications are central features of epitranscriptomics, highlighted by the discovery of modified ribonucleosides in mRNA and exemplified by the critical roles of RNA modifications in normal physiology and disease. Despite a resurgent interest in these modifications, the biochemistry of 3-methylcytidine (m3C) formation in mammalian RNAs is still poorly understood. However, the recent discovery of trm141 as the second gene responsible for m3C presence in RNA in fission yeast raises the possibility that multiple enzymes are involved in m3C formation in mammals as well. Here, we report the discovery and characterization of three distinct m3C-contributing enzymes in mice and humans. We found that methyltransferase-like (METTL) 2 and 6 contribute m3C in specific tRNAs and that METTL8 only contributes m3C to mRNA. MS analysis revealed that there is an ∼30-40% and ∼10-15% reduction, respectively, in METTL2 and -6 null-mutant cells, of m3C in total tRNA, and primer extension analysis located METTL2-modified m3C at position 32 of tRNAThr isoacceptors and tRNAArg(CCU) We also noted that METTL6 interacts with seryl-tRNA synthetase in an RNA-dependent manner, suggesting a role for METTL6 in modifying serine tRNA isoacceptors. METTL8, however, modified only mRNA, as determined by biochemical and genetic analyses in Mettl8 null-mutant mice and two human METTL8 mutant cell lines. Our findings provide the first evidence of the existence of m3C modification in mRNA, and the discovery of METTL8 as an mRNA m3C writer enzyme opens the door to future studies of other m3C epitranscriptomic reader and eraser functions.
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Affiliation(s)
- Luang Xu
- From the Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, 117599 Singapore
| | - Xinyu Liu
- From the Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, 117599 Singapore
| | - Na Sheng
- the Model Animal Research Center of Nanjing University, 12 Xuefu Road, 210032 Nanjing, China
| | - Kyaw Soe Oo
- From the Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, 117599 Singapore
| | - Junxin Liang
- the Department of Biochemistry, National University of Singapore, 8 Medical Drive, 117596 Singapore
| | - Yok Hian Chionh
- the Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, 138602 Singapore
| | - Juan Xu
- the Model Animal Research Center of Nanjing University, 12 Xuefu Road, 210032 Nanjing, China
| | - Fuzhou Ye
- the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore, and
| | - Yong-Gui Gao
- the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore, and
| | - Peter C Dedon
- the Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, 138602 Singapore, .,the Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Xin-Yuan Fu
- From the Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, 117599 Singapore, .,the Model Animal Research Center of Nanjing University, 12 Xuefu Road, 210032 Nanjing, China.,the Department of Biochemistry, National University of Singapore, 8 Medical Drive, 117596 Singapore
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62
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Abstract
All types of nucleic acids in cells undergo naturally occurring chemical modifications, including DNA, rRNA, mRNA, snRNA, and most prominently tRNA. Over 100 different modifications have been described and every position in the purine and pyrimidine bases can be modified; often the sugar is also modified [1]. In tRNA, the function of modifications varies; some modulate global and/or local RNA structure, and others directly impact decoding and may be essential for viability. Whichever the case, the overall importance of modifications is highlighted by both their evolutionary conservation and the fact that organisms use a substantial portion of their genomes to encode modification enzymes, far exceeding what is needed for the de novo synthesis of the canonical nucleotides themselves [2]. Although some modifications occur at exactly the same nucleotide position in tRNAs from the three domains of life, many can be found at various positions in a particular tRNA and their location may vary between and within different tRNAs. With this wild array of chemical diversity and substrate specificities, one of the big challenges in the tRNA modification field has been to better understand at a molecular level the modes of substrate recognition by the different modification enzymes; in this realm RNA binding rests at the heart of the problem. This chapter will focus on several examples of modification enzymes where their mode of RNA binding is well understood; from these, we will try to draw general conclusions and highlight growing themes that may be applicable to the RNA modification field at large.
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63
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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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64
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Han L, Marcus E, D'Silva S, Phizicky EM. S. cerevisiae Trm140 has two recognition modes for 3-methylcytidine modification of the anticodon loop of tRNA substrates. RNA (NEW YORK, N.Y.) 2017; 23:406-419. [PMID: 28003514 PMCID: PMC5311504 DOI: 10.1261/rna.059667.116] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/12/2016] [Indexed: 05/25/2023]
Abstract
The 3-methylcytidine (m3C) modification is ubiquitous in eukaryotic tRNA, widely found at C32 in the anticodon loop of tRNAThr, tRNASer, and some tRNAArg species, as well as in the variable loop (V-loop) of certain tRNASer species. In the yeast Saccharomyces cerevisiae, formation of m3C32 requires Trm140 for six tRNA substrates, including three tRNAThr species and three tRNASer species, whereas in Schizosaccharomyces pombe, two Trm140 homologs are used, one for tRNAThr and one for tRNASer The occurrence of a single Trm140 homolog is conserved broadly among Ascomycota, whereas multiple Trm140-related homologs are found in metazoans and other fungi. We investigate here how S. cerevisiae Trm140 protein recognizes its six tRNA substrates. We show that Trm140 has two modes of tRNA substrate recognition. Trm140 recognizes G35-U36-t6A37 of the anticodon loop of tRNAThr substrates, and this sequence is an identity element because it can be used to direct m3C modification of tRNAPhe However, Trm140 recognition of tRNASer substrates is different, since their anticodons do not share G35-U36 and do not have any nucleotides in common. Rather, specificity of Trm140 for tRNASer is achieved by seryl-tRNA synthetase and the distinctive tRNASer V-loop, as well as by t6A37 and i6A37 We provide evidence that all of these components are important in vivo and that seryl-tRNA synthetase greatly stimulates m3C modification of tRNASer(CGA) and tRNASer(UGA) in vitro. In addition, our results show that Trm140 binding is a significant driving force for tRNA modification and suggest separate contributions from each recognition element for the modification.
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MESH Headings
- Anticodon/chemistry
- Anticodon/metabolism
- Base Sequence
- Binding Sites
- Cloning, Molecular
- Cytidine/analogs & derivatives
- Cytidine/genetics
- Cytidine/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression
- Microfilament Proteins/genetics
- Microfilament Proteins/metabolism
- Nucleic Acid Conformation
- Protein Binding
- Protein Biosynthesis
- Protein Domains
- RNA, Transfer, Phe/chemistry
- RNA, Transfer, Phe/genetics
- RNA, Transfer, Phe/metabolism
- RNA, Transfer, Ser/chemistry
- RNA, Transfer, Ser/genetics
- RNA, Transfer, Ser/metabolism
- RNA, Transfer, Thr/chemistry
- RNA, Transfer, Thr/genetics
- RNA, Transfer, Thr/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
- Substrate Specificity
- tRNA Methyltransferases/genetics
- tRNA Methyltransferases/metabolism
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Affiliation(s)
- Lu Han
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Erin Marcus
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
| | - Sonia D'Silva
- 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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