1
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Li ZH, Zhou XL. Eukaryotic AlaX provides multiple checkpoints for quality and quantity of aminoacyl-tRNAs in translation. Nucleic Acids Res 2024; 52:7825-7842. [PMID: 38869066 PMCID: PMC11260482 DOI: 10.1093/nar/gkae486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/27/2024] [Indexed: 06/14/2024] Open
Abstract
Translational fidelity relies critically on correct aminoacyl-tRNA supply. The trans-editing factor AlaX predominantly hydrolyzes Ser-tRNAAla, functioning as a third sieve of alanyl-tRNA synthetase (AlaRS). Despite extensive studies in bacteria and archaea, the mechanism of trans-editing in mammals remains largely unknown. Here, we show that human AlaX (hAlaX), which is exclusively distributed in the cytoplasm, is an active trans-editing factor with strict Ser-specificity. In vitro, both hAlaX and yeast AlaX (ScAlaX) were capable of hydrolyzing nearly all Ser-mischarged cytoplasmic and mitochondrial tRNAs; and robustly edited cognate Ser-charged cytoplasmic and mitochondrial tRNASers. In vivo or cell-based studies revealed that loss of ScAlaX or hAlaX readily induced Ala- and Thr-to-Ser misincorporation. Overexpression of hAlaX impeded the decoding efficiency of consecutive Ser codons, implying its regulatory role in Ser codon decoding. Remarkably, yeast cells with ScAlaX deletion responded differently to translation inhibitor treatment, with a gain in geneticin resistance, but sensitivity to cycloheximide, both of which were rescued by editing-capable ScAlaX, alanyl- or threonyl-tRNA synthetase. Altogether, our results demonstrated the previously undescribed editing peculiarities of eukaryotic AlaXs, which provide multiple checkpoints to maintain the speed and fidelity of genetic decoding.
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Affiliation(s)
- Zi-Han Li
- Key Laboratory of RNA Innovation, Science and Engineering, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Xiao-Long Zhou
- Key Laboratory of RNA Innovation, Science and Engineering, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
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2
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McCutcheon JP, Garber AI, Spencer N, Warren JM. How do bacterial endosymbionts work with so few genes? PLoS Biol 2024; 22:e3002577. [PMID: 38626194 PMCID: PMC11020763 DOI: 10.1371/journal.pbio.3002577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024] Open
Abstract
The move from a free-living environment to a long-term residence inside a host eukaryotic cell has profound effects on bacterial function. While endosymbioses are found in many eukaryotes, from protists to plants to animals, the bacteria that form these host-beneficial relationships are even more diverse. Endosymbiont genomes can become radically smaller than their free-living relatives, and their few remaining genes show extreme compositional biases. The details of how these reduced and divergent gene sets work, and how they interact with their host cell, remain mysterious. This Unsolved Mystery reviews how genome reduction alters endosymbiont biology and highlights a "tipping point" where the loss of the ability to build a cell envelope coincides with a marked erosion of translation-related genes.
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Affiliation(s)
- John P. McCutcheon
- Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Arkadiy I. Garber
- Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Noah Spencer
- Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Jessica M. Warren
- Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
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3
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Antika TR, Nazilah KR, Chrestella DJ, Wang TL, Tseng YK, Wang SC, Hsu HL, Wang SW, Chuang TH, Pan HC, Horng JC, Wang CC. Sequence-specific targeting of Caenorhabditis elegans C-Ala to the D-loop of tRNA Ala. J Biol Chem 2023; 299:105149. [PMID: 37567477 PMCID: PMC10485164 DOI: 10.1016/j.jbc.2023.105149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/13/2023] Open
Abstract
Alanyl-tRNA synthetase retains a conserved prototype structure throughout its biology. Nevertheless, its C-terminal domain (C-Ala) is highly diverged and has been shown to play a role in either tRNA or DNA binding. Interestingly, we discovered that Caenorhabditis elegans cytoplasmic C-Ala (Ce-C-Alac) robustly binds both ligands. How Ce-C-Alac targets its cognate tRNA and whether a similar feature is conserved in its mitochondrial counterpart remain elusive. We show that the N- and C-terminal subdomains of Ce-C-Alac are responsible for DNA and tRNA binding, respectively. Ce-C-Alac specifically recognized the conserved invariant base G18 in the D-loop of tRNAAla through a highly conserved lysine residue, K934. Despite bearing little resemblance to other C-Ala domains, C. elegans mitochondrial C-Ala robustly bound both tRNAAla and DNA and maintained targeting specificity for the D-loop of its cognate tRNA. This study uncovers the underlying mechanism of how C. elegans C-Ala specifically targets the D-loop of tRNAAla.
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Affiliation(s)
- Titi Rindi Antika
- Department of Life Sciences, National Central University, Taoyuan, Taiwan
| | | | | | - Tzu-Ling Wang
- Graduate Institute of Mathematics and Science Education, National Tsing Hua University, Hsinchu City, Taiwan
| | - Yi-Kuan Tseng
- Graduate Institute of Statistics, National Central University, Taoyuan, Taiwan
| | - Sun-Chong Wang
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan
| | - Hsin-Ling Hsu
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan
| | - Shao-Win Wang
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan
| | - Tsung-Hsien Chuang
- Immunology Research Center, National Health Research Institutes, Miaoli, Taiwan
| | - Hung-Chuan Pan
- Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Jia-Cherng Horng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Chien-Chia Wang
- Department of Life Sciences, National Central University, Taoyuan, Taiwan.
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4
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Kuhle B, Hirschi M, Doerfel LK, Lander GC, Schimmel P. Structural basis for a degenerate tRNA identity code and the evolution of bimodal specificity in human mitochondrial tRNA recognition. Nat Commun 2023; 14:4794. [PMID: 37558671 PMCID: PMC10412605 DOI: 10.1038/s41467-023-40354-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 07/22/2023] [Indexed: 08/11/2023] Open
Abstract
Animal mitochondrial gene expression relies on specific interactions between nuclear-encoded aminoacyl-tRNA synthetases and mitochondria-encoded tRNAs. Their evolution involves an antagonistic interplay between strong mutation pressure on mtRNAs and selection pressure to maintain their essential function. To understand the molecular consequences of this interplay, we analyze the human mitochondrial serylation system, in which one synthetase charges two highly divergent mtRNASer isoacceptors. We present the cryo-EM structure of human mSerRS in complex with mtRNASer(UGA), and perform a structural and functional comparison with the mSerRS-mtRNASer(GCU) complex. We find that despite their common function, mtRNASer(UGA) and mtRNASer(GCU) show no constrain to converge on shared structural or sequence identity motifs for recognition by mSerRS. Instead, mSerRS evolved a bimodal readout mechanism, whereby a single protein surface recognizes degenerate identity features specific to each mtRNASer. Our results show how the mutational erosion of mtRNAs drove a remarkable innovation of intermolecular specificity rules, with multiple evolutionary pathways leading to functionally equivalent outcomes.
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Affiliation(s)
- Bernhard Kuhle
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA.
- Department of Cellular Biochemistry, University Medical Center Göttingen, 37073, Göttingen, Germany.
| | - Marscha Hirschi
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Lili K Doerfel
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA
- The Scripps Florida Research Institute at the University of Florida, Jupiter, FL, 33458, USA
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5
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Antika TR, Chrestella DJ, Tseng YK, Yeh YH, Hsiao CD, Wang CC. A naturally occurring mini-alanyl-tRNA synthetase. Commun Biol 2023; 6:314. [PMID: 36959394 PMCID: PMC10036535 DOI: 10.1038/s42003-023-04699-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 03/13/2023] [Indexed: 03/25/2023] Open
Abstract
Alanyl-tRNA synthetase (AlaRS) retains a conserved prototype structure throughout its biology, consisting of catalytic, tRNA-recognition, editing, and C-Ala domains. The catalytic and tRNA-recognition domains catalyze aminoacylation, the editing domain hydrolyzes mischarged tRNAAla, and C-Ala-the major tRNA-binding module-targets the elbow of the L-shaped tRNAAla. Interestingly, a mini-AlaRS lacking the editing and C-Ala domains is recovered from the Tupanvirus of the amoeba Acanthamoeba castellanii. Here we show that Tupanvirus AlaRS (TuAlaRS) is phylogenetically related to its host's AlaRS. Despite lacking the conserved amino acid residues responsible for recognition of the identity element of tRNAAla (G3:U70), TuAlaRS still specifically recognized G3:U70-containing tRNAAla. In addition, despite lacking C-Ala, TuAlaRS robustly binds and charges microAla (an RNA substrate corresponding to the acceptor stem of tRNAAla) as well as tRNAAla, indicating that TuAlaRS exclusively targets the acceptor stem. Moreover, this mini-AlaRS could functionally substitute for yeast AlaRS in vivo. This study suggests that TuAlaRS has developed a new tRNA-binding mode to compensate for the loss of C-Ala.
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Affiliation(s)
- Titi Rindi Antika
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan, 320317, Taiwan
| | - Dea Jolie Chrestella
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan, 320317, Taiwan
| | - Yi-Kuan Tseng
- Graduate Institute of Statistics, National Central University, Zhongli District, Taoyuan, 320317, Taiwan
| | - Yi-Hung Yeh
- Institute of Molecular Biology, Academia Sinica, Nankang District, Taipei, 11529, Taiwan
| | - Chwan-Deng Hsiao
- Institute of Molecular Biology, Academia Sinica, Nankang District, Taipei, 11529, Taiwan
| | - Chien-Chia Wang
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan, 320317, Taiwan.
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6
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Giegé R, Eriani G. The tRNA identity landscape for aminoacylation and beyond. Nucleic Acids Res 2023; 51:1528-1570. [PMID: 36744444 PMCID: PMC9976931 DOI: 10.1093/nar/gkad007] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 12/21/2022] [Accepted: 01/03/2023] [Indexed: 02/07/2023] Open
Abstract
tRNAs are key partners in ribosome-dependent protein synthesis. This process is highly dependent on the fidelity of tRNA aminoacylation by aminoacyl-tRNA synthetases and relies primarily on sets of identities within tRNA molecules composed of determinants and antideterminants preventing mischarging by non-cognate synthetases. Such identity sets were discovered in the tRNAs of a few model organisms, and their properties were generalized as universal identity rules. Since then, the panel of identity elements governing the accuracy of tRNA aminoacylation has expanded considerably, but the increasing number of reported functional idiosyncrasies has led to some confusion. In parallel, the description of other processes involving tRNAs, often well beyond aminoacylation, has progressed considerably, greatly expanding their interactome and uncovering multiple novel identities on the same tRNA molecule. This review highlights key findings on the mechanistics and evolution of tRNA and tRNA-like identities. In addition, new methods and their results for searching sets of multiple identities on a single tRNA are discussed. Taken together, this knowledge shows that a comprehensive understanding of the functional role of individual and collective nucleotide identity sets in tRNA molecules is needed for medical, biotechnological and other applications.
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Affiliation(s)
- Richard Giegé
- Correspondence may also be addressed to Richard Giegé.
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7
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Kuhle B, Hirschi M, Doerfel LK, Lander GC, Schimmel P. Structural basis for shape-selective recognition and aminoacylation of a D-armless human mitochondrial tRNA. Nat Commun 2022; 13:5100. [PMID: 36042193 PMCID: PMC9427863 DOI: 10.1038/s41467-022-32544-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/04/2022] [Indexed: 02/05/2023] Open
Abstract
Human mitochondrial gene expression relies on the specific recognition and aminoacylation of mitochondrial tRNAs (mtRNAs) by nuclear-encoded mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs). Despite their essential role in cellular energy homeostasis, strong mutation pressure and genetic drift have led to an unparalleled sequence erosion of animal mtRNAs. The structural and functional consequences of this erosion are not understood. Here, we present cryo-EM structures of the human mitochondrial seryl-tRNA synthetase (mSerRS) in complex with mtRNASer(GCU). These structures reveal a unique mechanism of substrate recognition and aminoacylation. The mtRNASer(GCU) is highly degenerated, having lost the entire D-arm, tertiary core, and stable L-shaped fold that define canonical tRNAs. Instead, mtRNASer(GCU) evolved unique structural innovations, including a radically altered T-arm topology that serves as critical identity determinant in an unusual shape-selective readout mechanism by mSerRS. Our results provide a molecular framework to understand the principles of mito-nuclear co-evolution and specialized mechanisms of tRNA recognition in mammalian mitochondrial gene expression.
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Affiliation(s)
- Bernhard Kuhle
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | - Marscha Hirschi
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Lili K Doerfel
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92121, USA
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92037, USA
- The Scripps Florida Research Institute at the University of Florida, Jupiter, FL, 33458, USA
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8
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Antika TR, Chrestella DJ, Ivanesthi IR, Rida G, Chen KY, Liu FG, Lee YC, Chen YW, Tseng YK, Wang CC. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2190-2200. [PMID: 35100402 PMCID: PMC8887476 DOI: 10.1093/nar/gkac026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/14/2021] [Accepted: 01/11/2022] [Indexed: 11/14/2022] Open
Abstract
Unlike many other aminoacyl-tRNA synthetases, alanyl-tRNA synthetase (AlaRS) retains a conserved prototype structure throughout biology. While Caenorhabditis elegans cytoplasmic AlaRS (CeAlaRSc) retains the prototype structure, its mitochondrial counterpart (CeAlaRSm) contains only a residual C-terminal domain (C-Ala). We demonstrated herein that the C-Ala domain from CeAlaRSc robustly binds both tRNA and DNA. It bound different tRNAs but preferred tRNAAla. Deletion of this domain from CeAlaRSc sharply reduced its aminoacylation activity, while fusion of this domain to CeAlaRSm selectively and distinctly enhanced its aminoacylation activity toward the elbow-containing (or L-shaped) tRNAAla. Phylogenetic analysis showed that CeAlaRSm once possessed the C-Ala domain but later lost most of it during evolution, perhaps in response to the deletion of the T-arm (part of the elbow) from its cognate tRNA. This study underscores the evolutionary gain of C-Ala for docking AlaRS to the L-shaped tRNAAla.
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Affiliation(s)
- Titi Rindi Antika
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Dea Jolie Chrestella
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Indira Rizqita Ivanesthi
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Gita Riswana Nawung Rida
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Kuan-Yu Chen
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Fu-Guo Liu
- Department of Life Sciences, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Taipei Veterans General Hospital, Beitou District, Taipei 11217, Taiwan
| | - Yu-Wei Chen
- Department of Neurology, Landseed International Hospital, Pingzhen District, Taoyuan 32449, Taiwan
| | - Yi-Kuan Tseng
- Graduate Institute of Statistics, National Central University, Zhongli District, Taoyuan 32001, Taiwan
| | - Chien-Chia Wang
- To whom correspondence should be addressed. Tel: +886 3 426 0840; Fax: +886 3 422 8482;
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9
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Mechanistic insights into mitochondrial tRNA Ala 3'-end metabolism deficiency. J Biol Chem 2021; 297:100816. [PMID: 34023389 PMCID: PMC8212662 DOI: 10.1016/j.jbc.2021.100816] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/10/2021] [Accepted: 05/19/2021] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial tRNA 3’-end metabolism is critical for the formation of functional tRNAs. Deficient mitochondrial tRNA 3’-end metabolism is linked to an array of human diseases, including optic neuropathy, but their pathophysiology remains poorly understood. In this report, we investigated the molecular mechanism underlying the Leber’s hereditary optic neuropathy (LHON)-associated tRNAAla 5587A>G mutation, which changes a highly conserved adenosine at position 73 (A73) to guanine (G73) on the 3’-end of the tRNA acceptor stem. The m.5587A>G mutation was identified in three Han Chinese families with suggested maternal inheritance of LHON. We hypothesized that the m.5587A>G mutation altered tRNAAla 3’-end metabolism and mitochondrial function. In vitro processing experiments showed that the m.5587A>G mutation impaired the 3’-end processing of tRNAAla precursors by RNase Z and inhibited the addition of CCA by tRNA nucleotidyltransferase (TRNT1). Northern blot analysis revealed that the m.5587A>G mutation perturbed tRNAAla aminoacylation, as evidenced by decreased efficiency of aminoacylation and faster electrophoretic mobility of mutated tRNAAla in these cells. The impact of m.5587A>G mutation on tRNAAla function was further supported by increased melting temperature, conformational changes, and reduced levels of this tRNA. Failures in tRNAAla metabolism impaired mitochondrial translation, perturbed assembly and activity of oxidative phosphorylation complexes, diminished ATP production and membrane potential, and increased production of reactive oxygen species. These pleiotropic defects elevated apoptotic cell death and promoted mitophagy in cells carrying the m.5587A>G mutation, thereby contributing to visual impairment. Our findings may provide new insights into the pathophysiology of LHON arising from mitochondrial tRNA 3’-end metabolism deficiency.
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10
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Plazzi F, Puccio G, Passamonti M. HERMES: An improved method to test mitochondrial genome molecular synapomorphies among clades. Mitochondrion 2021; 58:285-295. [PMID: 33639269 DOI: 10.1016/j.mito.2021.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/10/2021] [Accepted: 02/12/2021] [Indexed: 02/06/2023]
Abstract
Mitochondrial chromosomes have diversified among eukaryotes and many different architectures and features are now acknowledged for this genome. Here we present the improved HERMES index, which can measure and quantify the amount of molecular change experienced by mitochondrial genomes. We test the improved approach with ten molecular phylogenetic studies based on complete mitochondrial genomes, representing six bilaterian Phyla. In most cases, HERMES analysis spotted out clades or single species with peculiar molecular synapomorphies, allowing to identify phylogenetic and ecological patterns. The software presented herein handles linear, circular, and multi-chromosome genomes, thus widening the HERMES scope to the complete eukaryotic domain.
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Affiliation(s)
- Federico Plazzi
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
| | - Guglielmo Puccio
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
| | - Marco Passamonti
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
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11
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Richter U, McFarland R, Taylor RW, Pickett SJ. The molecular pathology of pathogenic mitochondrial tRNA variants. FEBS Lett 2021; 595:1003-1024. [PMID: 33513266 PMCID: PMC8600956 DOI: 10.1002/1873-3468.14049] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 12/16/2022]
Abstract
Mitochondrial diseases are clinically and genetically heterogeneous disorders, caused by pathogenic variants in either the nuclear or mitochondrial genome. This heterogeneity is particularly striking for disease caused by variants in mitochondrial DNA‐encoded tRNA (mt‐tRNA) genes, posing challenges for both the treatment of patients and understanding the molecular pathology. In this review, we consider disease caused by the two most common pathogenic mt‐tRNA variants: m.3243A>G (within MT‐TL1, encoding mt‐tRNALeu(UUR)) and m.8344A>G (within MT‐TK, encoding mt‐tRNALys), which together account for the vast majority of all mt‐tRNA‐related disease. We compare and contrast the clinical disease they are associated with, as well as their molecular pathologies, and consider what is known about the likely molecular mechanisms of disease. Finally, we discuss the role of mitochondrial–nuclear crosstalk in the manifestation of mt‐tRNA‐associated disease and how research in this area not only has the potential to uncover molecular mechanisms responsible for the vast clinical heterogeneity associated with these variants but also pave the way to develop treatment options for these devastating diseases.
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Affiliation(s)
- Uwe Richter
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland.,Newcastle University Biosciences Institute, Newcastle University, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
| | - Sarah J Pickett
- Wellcome Centre for Mitochondrial Research, The Medical School, Newcastle University, UK.,Newcastle University Translational and Clinical Research Institute, Newcastle University, UK
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12
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Abstract
Among the 20 cytoplasmic aminoacyl-tRNA synthetases (aaRSs), alanyl-tRNA synthetase (AlaRS) has unique features. AlaRS is the only aaRS that exclusively recognizes a single G3:U70 wobble base pair in the acceptor stem of tRNA, which serves as the identity element for both the synthetic and the proofreading activities of the synthetase. The recognition is relaxed during evolution and eukaryotic AlaRS can mis-aminoacylate noncognate tRNAs with a G4:U69 base pair seemingly as a deliberate gain of function for unknown reasons. Unlike other class II aaRSs, dimerization of AlaRS is not necessarily required for aminoacylation possibly due to functional compensations from the C-terminal domain (C-Ala). In contrast to other 19 cytoplasmic aaRSs that append additional domains or motifs to acquire new functions during evolution, the functional expansion of AlaRS is likely achieved through transformations of the existing C-Ala. Given both essential canonical and diverse non-canonical roles of AlaRS, dysfunction of AlaRS leads to neurodegenerative disorders in human and various pathological phenotypes in mouse models. In this review, the uniqueness of AlaRS in both physiological and pathological events is systematically discussed, with a particular focus on its novel functions gained in evolution.
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Affiliation(s)
- Han Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, Yunnan, China
| | - Xiang-Lei Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - Litao Sun
- School of Public Health (Shenzhen), Sun Yat-sen University, Guangdong, China
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13
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Mukai T. Rational Design of Aptamer-Tagged tRNAs. Int J Mol Sci 2020; 21:ijms21207793. [PMID: 33096801 PMCID: PMC7590224 DOI: 10.3390/ijms21207793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 11/16/2022] Open
Abstract
Reprogramming of the genetic code system is limited by the difficulty in creating new tRNA structures. Here, I developed translationally active tRNA variants tagged with a small hairpin RNA aptamer, using Escherichia coli reporter assay systems. As the tRNA chassis for engineering, I employed amber suppressor variants of allo-tRNAs having the 9/3 composition of the 12-base pair amino-acid acceptor branch as well as a long variable arm (V-arm). Although their V-arm is a strong binding site for seryl-tRNA synthetase (SerRS), insertion of a bulge nucleotide in the V-arm stem region prevented allo-tRNA molecules from being charged by SerRS with serine. The SerRS-rejecting allo-tRNA chassis were engineered to have another amino-acid identity of either alanine, tyrosine, or histidine. The tip of the V-arms was replaced with diverse hairpin RNA aptamers, which were recognized by their cognate proteins expressed in E. coli. A high-affinity interaction led to the sequestration of allo-tRNA molecules, while a moderate-affinity aptamer moiety recruited histidyl-tRNA synthetase variants fused with the cognate protein domain. The new design principle for tRNA-aptamer fusions will enhance radical and dynamic manipulation of the genetic code.
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Affiliation(s)
- Takahito Mukai
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
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14
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Garin S, Levi O, Cohen B, Golani-Armon A, Arava YS. Localization and RNA Binding of Mitochondrial Aminoacyl tRNA Synthetases. Genes (Basel) 2020; 11:genes11101185. [PMID: 33053729 PMCID: PMC7600831 DOI: 10.3390/genes11101185] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/05/2020] [Accepted: 10/08/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria contain a complete translation machinery that is used to translate its internally transcribed mRNAs. This machinery uses a distinct set of tRNAs that are charged with cognate amino acids inside the organelle. Interestingly, charging is executed by aminoacyl tRNA synthetases (aaRS) that are encoded by the nuclear genome, translated in the cytosol, and need to be imported into the mitochondria. Here, we review import mechanisms of these enzymes with emphasis on those that are localized to both mitochondria and cytosol. Furthermore, we describe RNA recognition features of these enzymes and their interaction with tRNA and non-tRNA molecules. The dual localization of mitochondria-destined aaRSs and their association with various RNA types impose diverse impacts on cellular physiology. Yet, the breadth and significance of these functions are not fully resolved. We highlight here possibilities for future explorations.
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15
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Hill GE. Mitonuclear Compensatory Coevolution. Trends Genet 2020; 36:403-414. [PMID: 32396834 DOI: 10.1016/j.tig.2020.03.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/27/2020] [Accepted: 03/08/2020] [Indexed: 01/03/2023]
Abstract
In bilaterian animals, the mitochondrial genome is small, haploid, does not typically recombine, and is subject to accumulation of deleterious alleles via Muller's ratchet. These basic features of the genomic architecture present a paradox: mutational erosion of these genomes should lead to decline in mitochondrial function over time, yet no such decline is observed. Compensatory coevolution, whereby the nuclear genome evolves to compensate for the deleterious alleles in the mitochondrial genome, presents a potential solution to the paradox of Muller's ratchet without loss of function. Here, I review different proposed forms of mitonuclear compensatory coevolution. Empirical evidence from diverse eukaryotic taxa supports the mitonuclear compensatory coevolution hypothesis, but the ubiquity and importance of such compensatory coevolution remains a topic of debate.
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Affiliation(s)
- Geoffrey E Hill
- Department of Biological Science, 331 Funchess Hall, Auburn University, Auburn, AL 36849-5414, USA.
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16
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Mitochondrial aminoacyl-tRNA synthetases. Enzymes 2020. [PMID: 33837704 DOI: 10.1016/bs.enz.2020.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
Abstract
In all eukaryotic cells, protein synthesis occurs not only in the cytosol, but also in the mitochondria. Translation of mitochondrial genes requires a set of aminoacyl-tRNA synthetases, many of which are often specialized for organellar function. These enzymes have evolved unique mechanisms for tRNA recognition and for ensuring fidelity of translation. Mutations of human mitochondrial synthetases are associated with a wide range of pathogenic phenotypes, both highlighting the importance of their role in maintaining the cellular "powerhouse" and suggesting additional cellular roles.
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