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Zhao X, Ma D, Ishiguro K, Saito H, Akichika S, Matsuzawa I, Mito M, Irie T, Ishibashi K, Wakabayashi K, Sakaguchi Y, Yokoyama T, Mishima Y, Shirouzu M, Iwasaki S, Suzuki T, Suzuki T. Glycosylated queuosines in tRNAs optimize translational rate and post-embryonic growth. Cell 2023; 186:5517-5535.e24. [PMID: 37992713 DOI: 10.1016/j.cell.2023.10.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 08/14/2023] [Accepted: 10/26/2023] [Indexed: 11/24/2023]
Abstract
Transfer RNA (tRNA) modifications are critical for protein synthesis. Queuosine (Q), a 7-deaza-guanosine derivative, is present in tRNA anticodons. In vertebrate tRNAs for Tyr and Asp, Q is further glycosylated with galactose and mannose to generate galQ and manQ, respectively. However, biogenesis and physiological relevance of Q-glycosylation remain poorly understood. Here, we biochemically identified two RNA glycosylases, QTGAL and QTMAN, and successfully reconstituted Q-glycosylation of tRNAs using nucleotide diphosphate sugars. Ribosome profiling of knockout cells revealed that Q-glycosylation slowed down elongation at cognate codons, UAC and GAC (GAU), respectively. We also found that galactosylation of Q suppresses stop codon readthrough. Moreover, protein aggregates increased in cells lacking Q-glycosylation, indicating that Q-glycosylation contributes to proteostasis. Cryo-EM of human ribosome-tRNA complex revealed the molecular basis of codon recognition regulated by Q-glycosylations. Furthermore, zebrafish qtgal and qtman knockout lines displayed shortened body length, implying that Q-glycosylation is required for post-embryonic growth in vertebrates.
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Affiliation(s)
- Xuewei Zhao
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Ding Ma
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Kensuke Ishiguro
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa 230-0045, Japan
| | - Hironori Saito
- RNA System Biochemistry Laboratory, Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Shinichiro Akichika
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Ikuya Matsuzawa
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Mari Mito
- RNA System Biochemistry Laboratory, Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Toru Irie
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Kota Ishibashi
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Kimi Wakabayashi
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan
| | - Takeshi Yokoyama
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa 230-0045, Japan; Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Yuichiro Mishima
- Faculty of Life Sciences, Kyoto Sangyo University, Kita-ku, Kyoto 603-8555, Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa 230-0045, Japan
| | - Shintaro Iwasaki
- RNA System Biochemistry Laboratory, Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan.
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2
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Shtolz N, Mishmar D. The metazoan landscape of mitochondrial DNA gene order and content is shaped by selection and affects mitochondrial transcription. Commun Biol 2023; 6:93. [PMID: 36690686 PMCID: PMC9871016 DOI: 10.1038/s42003-023-04471-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 01/12/2023] [Indexed: 01/25/2023] Open
Abstract
Mitochondrial DNA (mtDNA) harbors essential genes in most metazoans, yet the regulatory impact of the multiple evolutionary mtDNA rearrangements has been overlooked. Here, by analyzing mtDNAs from ~8000 metazoans we found high gene content conservation (especially of protein and rRNA genes), and codon preferences for mtDNA-encoded tRNAs across most metazoans. In contrast, mtDNA gene order (MGO) was selectively constrained within but not between phyla, yet certain gene stretches (ATP8-ATP6, ND4-ND4L) were highly conserved across metazoans. Since certain metazoans with different MGOs diverge in mtDNA transcription, we hypothesized that evolutionary mtDNA rearrangements affected mtDNA transcriptional patterns. As a first step to test this hypothesis, we analyzed available RNA-seq data from 53 metazoans. Since polycistron mtDNA transcripts constitute a small fraction of the steady-state RNA, we enriched for polycistronic boundaries by calculating RNA-seq read densities across junctions between gene couples encoded either by the same strand (SSJ) or by different strands (DSJ). We found that organisms whose mtDNA is organized in alternating reverse-strand/forward-strand gene blocks (mostly arthropods), displayed significantly reduced DSJ read counts, in contrast to organisms whose mtDNA genes are preferentially encoded by one strand (all chordates). Our findings suggest that mtDNA rearrangements are selectively constrained and likely impact mtDNA regulation.
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Affiliation(s)
- Noam Shtolz
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dan Mishmar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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3
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Li A, Sun X, Arguello AE, Kleiner RE. Chemical Method to Sequence 5-Formylcytosine on RNA. ACS Chem Biol 2022; 17:503-508. [PMID: 35212224 PMCID: PMC9357364 DOI: 10.1021/acschembio.1c00707] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Epitranscriptomic RNA modifications can regulate biological processes, but there remains a major gap in our ability to identify and measure individual modifications at nucleotide resolution. Here we present Mal-Seq, a chemical method for sequencing 5-formylcytosine (f5C) modifications on RNA based on the selective and efficient malononitrile-mediated labeling of f5C residues to generate adducts that are read as C-to-T mutations upon reverse transcription and polymerase chain reaction amplification. We apply Mal-Seq to characterize the prevalence of f5C at the wobble position of mt-tRNA(Met) in different organisms and tissue types and find that high-level f5C modification is present in mammals but lacking in lower eukaryotes. Our work sheds light on mitochondrial tRNA modifications throughout eukaryotic evolution and provides a general platform for characterizing the f5C epitranscriptome.
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Affiliation(s)
- Ang Li
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Xuemeng Sun
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - A Emilia Arguello
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Ralph E Kleiner
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Xu XD, Guan JY, Zhang ZY, Cao YR, Cai YY, Storey KB, Yu DN, Zhang JY. Insight into the Phylogenetic Relationships among Three Subfamilies within Heptageniidae (Insecta: Ephemeroptera) along with Low-Temperature Selection Pressure Analyses Using Mitogenomes. INSECTS 2021; 12:656. [PMID: 34357316 PMCID: PMC8307263 DOI: 10.3390/insects12070656] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 12/12/2022]
Abstract
We determined 15 complete and two nearly complete mitogenomes of Heptageniidae belonging to three subfamilies (Heptageniinae, Rhithrogeninae, and Ecdyonurinae) and six genera (Afronurus, Epeorus, Leucrocuta, Maccaffertium, Stenacron, and Stenonema). Species of Rhithrogeninae and Ecdyonurinae had the same gene rearrangement of CR-I-M-Q-M-ND2, whereas a novel gene rearrangement of CR-I-M-Q-NCR-ND2 was found in Heptageniinae. Non-coding regions (NCRs) of 25-47 bp located between trnA and trnR were observed in all mayflies of Heptageniidae, which may be a synapomorphy for Heptageniidae. Both the BI and ML phylogenetic analyses supported the monophyly of Heptageniidae and its subfamilies (Heptageniinae, Rhithrogeninae, and Ecdyonurinae). The phylogenetic results combined with gene rearrangements and NCR locations confirmed the relationship of the subfamilies as (Heptageniinae + (Rhithrogeninae + Ecdyonurinae)). To assess the effects of low-temperature stress on Heptageniidae species from Ottawa, Canada, we found 27 positive selection sites in eight protein-coding genes (PCGs) using the branch-site model. The selection pressure analyses suggested that mitochondrial PCGs underwent positive selection to meet the energy requirements under low-temperature stress.
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Affiliation(s)
- Xiao-Dong Xu
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
| | - Jia-Yin Guan
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
| | - Zi-Yi Zhang
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
| | - Yu-Rou Cao
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
| | - Yin-Yin Cai
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
| | - Kenneth B. Storey
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada;
| | - Dan-Na Yu
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
- Key Lab of Wildlife Biotechnology, Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua 321004, China
| | - Jia-Yong Zhang
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China; (X.-D.X.); (J.-Y.G.); (Z.-Y.Z.); (Y.-R.C.); (Y.-Y.C.)
- Key Lab of Wildlife Biotechnology, Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua 321004, China
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5
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Noutahi E, Calderon V, Blanchette M, El-Mabrouk N, Lang BF. Rapid Genetic Code Evolution in Green Algal Mitochondrial Genomes. Mol Biol Evol 2019; 36:766-783. [PMID: 30698742 PMCID: PMC6551751 DOI: 10.1093/molbev/msz016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Genetic code deviations involving stop codons have been previously reported in mitochondrial genomes of several green plants (Viridiplantae), most notably chlorophyte algae (Chlorophyta). However, as changes in codon recognition from one amino acid to another are more difficult to infer, such changes might have gone unnoticed in particular lineages with high evolutionary rates that are otherwise prone to codon reassignments. To gain further insight into the evolution of the mitochondrial genetic code in green plants, we have conducted an in-depth study across mtDNAs from 51 green plants (32 chlorophytes and 19 streptophytes). Besides confirming known stop-to-sense reassignments, our study documents the first cases of sense-to-sense codon reassignments in Chlorophyta mtDNAs. In several Sphaeropleales, we report the decoding of AGG codons (normally arginine) as alanine, by tRNA(CCU) of various origins that carry the recognition signature for alanine tRNA synthetase. In Chromochloris, we identify tRNA variants decoding AGG as methionine and the synonymous codon CGG as leucine. Finally, we find strong evidence supporting the decoding of AUA codons (normally isoleucine) as methionine in Pycnococcus. Our results rely on a recently developed conceptual framework (CoreTracker) that predicts codon reassignments based on the disparity between DNA sequence (codons) and the derived protein sequence. These predictions are then validated by an evaluation of tRNA phylogeny, to identify the evolution of new tRNAs via gene duplication and loss, and structural modifications that lead to the assignment of new tRNA identities and a change in the genetic code.
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Affiliation(s)
- Emmanuel Noutahi
- Département d'Informatique et de Recherche opérationnelle (DIRO), Université de Montréal, CP 6128 succursale Centre-Ville, Montreal, QC, Canada
| | - Virginie Calderon
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec, Canada
| | - Mathieu Blanchette
- School of Computer Science, McGill University, McConnell Engineering Bldg., Montréal, QC H3A 0E9, Canada
- McGill Centre for Bioinformatics, McGill University, Montréal, QC, Canada
| | - Nadia El-Mabrouk
- Département d'Informatique et de Recherche opérationnelle (DIRO), Université de Montréal, CP 6128 succursale Centre-Ville, Montreal, QC, Canada
| | - Bernd Franz Lang
- Département de Biochimie, Centre Robert Cedergren, Université de Montréal, CP 6128 succursale Centre-Ville, Montreal, QC, Canada
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6
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Martinez A, Yamashita S, Nagaike T, Sakaguchi Y, Suzuki T, Tomita K. Human BCDIN3D monomethylates cytoplasmic histidine transfer RNA. Nucleic Acids Res 2017; 45:5423-5436. [PMID: 28119416 PMCID: PMC5435960 DOI: 10.1093/nar/gkx051] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 01/19/2017] [Indexed: 11/13/2022] Open
Abstract
Human RNA methyltransferase BCDIN3D is overexpressed in breast cancer cells, and is related to the tumorigenic phenotype and poor prognosis of breast cancer. Here, we show that cytoplasmic tRNAHis is the primary target of BCDIN3D in human cells. Recombinant human BCDIN3D, expressed in Escherichia coli, monomethylates the 5΄-monophosphate of cytoplasmic tRNAHis efficiently in vitro. In BCDN3D-knockout cells, established by CRISPR/Cas9 editing, the methyl moiety at the 5΄-monophosphate of cytoplasmic tRNAHis is lost, and the exogenous expression of BCDIN3D in the knockout cells restores the modification in cytoplasmic tRNAHis. BCIDN3D recognizes the 5΄-guanosine nucleoside at position -1 (G-1) and the eight-nucleotide acceptor helix with the G-1-A73 mis-pair at the top of the acceptor stem of cytoplasmic tRNAHis, which are exceptional structural features among cytoplasmic tRNA species. While the monomethylation of the 5΄-monophosphate of cytoplasmic tRNAHis affects neither the overall aminoacylation process in vitro nor the steady-state level of cytoplasmic tRNAHisin vivo, it protects the cytoplasmic tRNAHis transcript from degradation in vitro. Thus, BCDIN3D acts as a cytoplasmic tRNAHis-specific 5΄-methylphosphate capping enzyme. The present results also suggest the possible involvement of the monomethylation of the 5΄-monophosphate of cytoplasmic tRNAHis and/or cytoplasmic tRNAHis itself in the tumorigenesis of breast cancer cells.
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Affiliation(s)
- Anna Martinez
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Seisuke Yamashita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Takashi Nagaike
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kozo Tomita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan
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7
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Nagao A, Ohara M, Miyauchi K, Yokobori SI, Yamagishi A, Watanabe K, Suzuki T. Hydroxylation of a conserved tRNA modification establishes non-universal genetic code in echinoderm mitochondria. Nat Struct Mol Biol 2017; 24:778-782. [PMID: 28783151 DOI: 10.1038/nsmb.3449] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/11/2017] [Indexed: 12/13/2022]
Abstract
The genetic code is not frozen but still evolving, which can result in the acquisition of 'dialectal' codons that deviate from the universal genetic code. RNA modifications in the anticodon region of tRNAs play a critical role in establishing such non-universal genetic codes. In echinoderm mitochondria, the AAA codon specifies asparagine instead of lysine. By analyzing mitochondrial (mt-) tRNALys isolated from the sea urchin (Mesocentrotus nudus), we discovered a novel modified nucleoside, hydroxy-N6-threonylcarbamoyladenosine (ht6A), 3' adjacent to the anticodon (position 37). Biochemical analysis revealed that ht6A37 has the ability to prevent mt-tRNALys from misreading AAA as lysine, thereby indicating that hydroxylation of N6-threonylcarbamoyladenosine (t6A) contributes to the establishment of the non-universal genetic code in echinoderm mitochondria.
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Affiliation(s)
- Asuteka Nagao
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Mitsuhiro Ohara
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Shin-Ichi Yokobori
- Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Akihiko Yamagishi
- Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Kimitsuna Watanabe
- Department of Applied Life Sciences, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
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8
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Agris PF, Narendran A, Sarachan K, Väre VYP, Eruysal E. The Importance of Being Modified: The Role of RNA Modifications in Translational Fidelity. Enzymes 2017; 41:1-50. [PMID: 28601219 DOI: 10.1016/bs.enz.2017.03.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The posttranscriptional modifications of tRNA's anticodon stem and loop (ASL) domain represent a third level, a third code, to the accuracy and efficiency of translating mRNA codons into the correct amino acid sequence of proteins. Modifications of tRNA's ASL domain are enzymatically synthesized and site specifically located at the anticodon wobble position-34 and 3'-adjacent to the anticodon at position-37. Degeneracy of the 64 Universal Genetic Codes and the limitation in the number of tRNA species require some tRNAs to decode more than one codon. The specific modification chemistries and their impact on the tRNA's ASL structure and dynamics enable one tRNA to decode cognate and "wobble codons" or to expand recognition to synonymous codons, all the while maintaining the translational reading frame. Some modified nucleosides' chemistries prestructure tRNA to read the two codons of a specific amino acid that shares a twofold degenerate codon box, and other chemistries allow a different tRNA to respond to all four codons of a fourfold degenerate codon box. Thus, tRNA ASL modifications are critical and mutations in genes for the modification enzymes and tRNA, the consequences of which is a lack of modification, lead to mistranslation and human disease. By optimizing tRNA anticodon chemistries, structure, and dynamics in all organisms, modifications ensure translational fidelity of mRNA transcripts.
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Affiliation(s)
- Paul F Agris
- The RNA Institute, State University of New York, Albany, NY, United States.
| | - Amithi Narendran
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Kathryn Sarachan
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Ville Y P Väre
- The RNA Institute, State University of New York, Albany, NY, United States
| | - Emily Eruysal
- The RNA Institute, State University of New York, Albany, NY, United States
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Duplication of Drosophila melanogaster mitochondrial EF-Tu: pre-adaptation to T-arm truncation and exclusion of bulky aminoacyl residues. Biochem J 2017; 474:957-969. [PMID: 28130490 DOI: 10.1042/bcj20160929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/24/2017] [Accepted: 01/27/2017] [Indexed: 11/17/2022]
Abstract
Translation elongation factor Tu (EF-Tu) delivers aminoacyl-tRNA (aa-tRNA) to ribosomes in protein synthesis. EF-Tu generally recognizes aminoacyl moieties and acceptor- and T-stems of aa-tRNAs. However, nematode mitochondrial (mt) tRNAs frequently lack all or part of the T-arm that is recognized by canonical EF-Tu. We previously reported that two distinct EF-Tu species, EF-Tu1 and EF-Tu2, respectively, recognize mt tRNAs lacking T-arms and D-arms in the mitochondria of the chromadorean nematode Caenorhabditis elegansC. elegans EF-Tu2 specifically recognizes the seryl moiety of serylated D-armless tRNAs. Mitochondria of the enoplean nematode Trichinella possess three structural types of tRNAs: T-armless tRNAs, D-armless tRNAs, and cloverleaf tRNAs with a short T-arm. Trichinella mt EF-Tu1 binds to all three types and EF-Tu2 binds only to D-armless Ser-tRNAs, showing an evolutionary intermediate state from canonical EF-Tu to chromadorean nematode (e.g. C. elegans) EF-Tu species. We report here that two EF-Tu species also participate in Drosophila melanogaster mitochondria. Both D. melanogaster EF-Tu1 and EF-Tu2 bound to cloverleaf and D-armless tRNAs. D. melanogaster EF-Tu1 has the ability to recognize T-armless tRNAs that do not evidently exist in D. melanogaster mitochondria, but do exist in related arthropod species. In addition, D. melanogaster EF-Tu2 preferentially bound to aa-tRNAs carrying small amino acids, but not to aa-tRNAs carrying bulky amino acids. These results suggest that the Drosophila mt translation system could be another intermediate state between the canonical and nematode mitochondria-type translation systems.
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10
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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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11
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Wang R, Luo Z, He K, Delaney MO, Chen D, Sheng J. Base pairing and structural insights into the 5-formylcytosine in RNA duplex. Nucleic Acids Res 2016; 44:4968-77. [PMID: 27079978 PMCID: PMC4889945 DOI: 10.1093/nar/gkw235] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/24/2016] [Indexed: 12/20/2022] Open
Abstract
5-Formylcytidine (f5C), a previously discovered natural nucleotide in the mitochondrial tRNA of many species including human, has been recently detected as the oxidative product of 5-methylcytidine (m5C) through 5-hydroxymethylcytidine (hm5C) in total RNA of mammalian cells. The discovery indicated that these cytosine derivatives in RNA might also play important epigenetic roles similar as in DNA, which has been intensively investigated in the past few years. In this paper, we studied the base pairing specificity of f5C in different RNA duplex contexts. We found that the 5-formyl group could increase duplex thermal stability and enhance base pairing specificity. We present three high-resolution crystal structures of an octamer RNA duplex [5′-GUA(f5C)GUAC-3′]2 that have been solved under three crystallization conditions with different buffers and pH values. Our results showed that the 5-formyl group is located in the same plane as the cytosine base and forms an intra-residue hydrogen bond with the amino group in the N4 position. In addition, this modification increases the base stacking between the f5C and the neighboring bases while not causing significant global and local structure perturbations. This work provides insights into the effects of 5-formylcytosine on RNA duplex.
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Affiliation(s)
- Rui Wang
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Zhipu Luo
- Synchrotron Radiation Research Section, MCL National Cancer Institute, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Kaizhang He
- Dharmacon, GE Healthcare, Lafayette, CO 80026, USA
| | | | - Doris Chen
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Jia Sheng
- Department of Chemistry, University at Albany, State University of New York, Albany, NY 12222, USA The RNA Institute, University at Albany, State University of New York, Albany, NY 12222, USA
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12
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Patra AK, Kwon YM, Kang SG, Fujiwara Y, Kim SJ. The complete mitochondrial genome sequence of the tubeworm Lamellibrachia satsuma and structural conservation in the mitochondrial genome control regions of Order Sabellida. Mar Genomics 2016; 26:63-71. [PMID: 26776396 DOI: 10.1016/j.margen.2015.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/30/2015] [Accepted: 12/30/2015] [Indexed: 11/18/2022]
Abstract
The control region of the mitochondrial genomes shows high variation in conserved sequence organizations, which follow distinct evolutionary patterns in different species or taxa. In this study, we sequenced the complete mitochondrial genome of Lamellibrachia satsuma from the cold-seep region of Kagoshima Bay, as a part of whole genome study and extensively studied the structural features and patterns of the control region sequences. We obtained 15,037 bp of mitochondrial genome using Illumina sequencing and identified the non-coding AT-rich region or control region (354 bp, AT=83.9%) located between trnH and trnR. We found 7 conserved sequence blocks (CSB), scattered throughout the control region of L. satsuma and other taxa of Annelida. The poly-TA stretches, which commonly form the stem of multiple stem-loop structures, are most conserved in the CSB-I and CSB-II regions. The mitochondrial genome of L. satsuma encodes a unique repetitive sequence in the control region, which forms a unique secondary structure in comparison to Lamellibrachia luymesi. Phylogenetic analyses of all protein-coding genes indicate that L. satsuma forms a monophyletic clade with L. luymesi along with other tubeworms found in cold-seep regions (genera: Lamellibrachia, Escarpia, and Seepiophila). In general, the control region sequences of Annelida could be aligned with certainty within each genus, and to some extent within the family, but with a higher rate of variation in conserved regions.
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Affiliation(s)
- Ajit Kumar Patra
- Marine Biotechnology Research Center, Korea Institute of Ocean Science & Technology, Ansan 426-744, Republic of Korea; Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon 305-333, Republic of Korea.
| | - Yong Min Kwon
- Marine Biotechnology Research Center, Korea Institute of Ocean Science & Technology, Ansan 426-744, Republic of Korea.
| | - Sung Gyun Kang
- Marine Biotechnology Research Center, Korea Institute of Ocean Science & Technology, Ansan 426-744, Republic of Korea; Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon 305-333, Republic of Korea.
| | - Yoshihiro Fujiwara
- Department of Marine Biodiversity Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan.
| | - Sang-Jin Kim
- Marine Biotechnology Research Center, Korea Institute of Ocean Science & Technology, Ansan 426-744, Republic of Korea; Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon 305-333, Republic of Korea; National Marine Biodiversity Institute of Korea, Seocheon 325-902, Republic of Korea.
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13
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Bezerra AR, Guimarães AR, Santos MAS. Non-Standard Genetic Codes Define New Concepts for Protein Engineering. Life (Basel) 2015; 5:1610-28. [PMID: 26569314 PMCID: PMC4695839 DOI: 10.3390/life5041610] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/12/2015] [Accepted: 10/21/2015] [Indexed: 11/16/2022] Open
Abstract
The essential feature of the genetic code is the strict one-to-one correspondence between codons and amino acids. The canonical code consists of three stop codons and 61 sense codons that encode 20% of the amino acid repertoire observed in nature. It was originally designated as immutable and universal due to its conservation in most organisms, but sequencing of genes from the human mitochondrial genomes revealed deviations in codon assignments. Since then, alternative codes have been reported in both nuclear and mitochondrial genomes and genetic code engineering has become an important research field. Here, we review the most recent concepts arising from the study of natural non-standard genetic codes with special emphasis on codon re-assignment strategies that are relevant to engineering genetic code in the laboratory. Recent tools for synthetic biology and current attempts to engineer new codes for incorporation of non-standard amino acids are also reviewed in this article.
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Affiliation(s)
- Ana R Bezerra
- Health Sciences Department, Institute for Biomedicine-iBiMED, University of Aveiro, Campus de Santiago, Aveiro 3810-193, Portugal.
| | - Ana R Guimarães
- Health Sciences Department, Institute for Biomedicine-iBiMED, University of Aveiro, Campus de Santiago, Aveiro 3810-193, Portugal.
| | - Manuel A S Santos
- Health Sciences Department, Institute for Biomedicine-iBiMED, University of Aveiro, Campus de Santiago, Aveiro 3810-193, Portugal.
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Ling J, O'Donoghue P, Söll D. Genetic code flexibility in microorganisms: novel mechanisms and impact on physiology. Nat Rev Microbiol 2015; 13:707-721. [PMID: 26411296 DOI: 10.1038/nrmicro3568] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The genetic code, initially thought to be universal and immutable, is now known to contain many variations, including biased codon usage, codon reassignment, ambiguous decoding and recoding. As a result of recent advances in the areas of genome sequencing, biochemistry, bioinformatics and structural biology, our understanding of genetic code flexibility has advanced substantially in the past decade. In this Review, we highlight the prevalence, evolution and mechanistic basis of genetic code variations in microorganisms, and we discuss how this flexibility of the genetic code affects microbial physiology.
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Affiliation(s)
- Jiqiang Ling
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Patrick O'Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada.,Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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15
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Pathways of Genetic Code Evolution in Ancient and Modern Organisms. J Mol Evol 2015; 80:229-43. [DOI: 10.1007/s00239-015-9686-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/03/2015] [Indexed: 10/23/2022]
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16
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Jones TE, Ribas de Pouplana L, Alexander RW. Evidence for late resolution of the aux codon box in evolution. J Biol Chem 2013; 288:19625-32. [PMID: 23696642 DOI: 10.1074/jbc.m112.449249] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Recognition strategies for tRNA aminoacylation are ancient and highly conserved, having been selected very early in the evolution of the genetic code. In most cases, the trinucleotide anticodons of tRNA are important identity determinants for aminoacylation by cognate aminoacyl-tRNA synthetases. However, a degree of ambiguity exists in the recognition of certain tRNA(Ile) isoacceptors that are initially transcribed with the methionine-specifying CAU anticodon. In most organisms, the C34 wobble position in these tRNA(Ile) precursors is rapidly modified to lysidine to prevent recognition by methionyl-tRNA synthetase (MRS) and production of a chimeric Met-tRNA(Ile) that would compromise translational fidelity. In certain bacteria, however, lysidine modification is not required for MRS rejection, indicating that this recognition strategy is not universally conserved and may be relatively recent. To explore the actual distribution of lysidine-dependent tRNA(Ile) rejection by MRS, we have investigated the ability of bacterial MRSs from different clades to differentiate cognate tRNACAU(Met) from near-cognate tRNACAU(Ile). Discrimination abilities vary greatly and appear unrelated to phylogenetic or structural features of the enzymes or sequence determinants of the tRNA. Our data indicate that tRNA(Ile) identity elements were established late and independently in different bacterial groups. We propose that the observed variation in MRS discrimination ability reflects differences in the evolution of genetic code machineries of emerging bacterial clades.
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Affiliation(s)
- Thomas E Jones
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109-7486, USA
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17
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Ohira T, Suzuki T, Miyauchi K, Suzuki T, Yokobori SI, Yamagishi A, Watanabe K. Decoding mechanism of non-universal genetic codes in Loligo bleekeri mitochondria. J Biol Chem 2013; 288:7645-7652. [PMID: 23362261 DOI: 10.1074/jbc.m112.439554] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-universal genetic codes are frequently found in animal mitochondrial decoding systems. In squid mitochondria, four codons deviate from the universal genetic code, namely AUA, UGA, and AGA/AGG (AGR) for Met, Trp, and Ser, respectively. To understand the molecular basis for establishing the non-universal genetic code, we isolated and analyzed five mitochondrial tRNAs from a squid, Loligo bleekeri. Primary structures of the isolated tRNAs, including their post-transcriptional modifications, were analyzed by mass spectrometry. tRNA(Met)(AUR) possessed an unmodified cytidine at the first position of the anticodon, suggesting that the AUA codon is deciphered by CAU anticodon via non-canonical A-C pairing. We identified 5-taurinomethyluridine (τm(5)U) at the first position of the anticodon in tRNA(Trp)(UGR). τm(5)U enables tRNA(Trp) to decipher UGR codons as Trp. In addition, 5-taurinomethyl-2-thiouridine (τm(5)s(2)U) was found in mitochondrial tRNAs for Leu(UUR) and Lys in L. bleekeri. This is the first discovery of τm(5)U and τm(5)s(2)U in molluscan mitochondrial tRNAs.
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Affiliation(s)
- Takayuki Ohira
- Department of Chemistry and Biotechnology, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Shin-Ichi Yokobori
- Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Akihiko Yamagishi
- Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Kimitsuna Watanabe
- Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan; Department of Biotechnology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Hyogo 679-5148, Japan.
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18
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Watanabe K, Yokobori SI. tRNA Modification and Genetic Code Variations in Animal Mitochondria. J Nucleic Acids 2011; 2011:623095. [PMID: 22007289 PMCID: PMC3191813 DOI: 10.4061/2011/623095] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/04/2011] [Indexed: 12/03/2022] Open
Abstract
In animal mitochondria, six codons have been known as nonuniversal genetic codes, which vary in the course of animal evolution. They are UGA (termination codon in the universal genetic code changes to Trp codon in all animal mitochondria), AUA (Ile to Met in most metazoan mitochondria), AAA (Lys to Asn in echinoderm and some platyhelminth mitochondria), AGA/AGG (Arg to Ser in most invertebrate, Arg to Gly in tunicate, and Arg to termination in vertebrate mitochondria), and UAA (termination to Tyr in a planaria and a nematode mitochondria, but conclusive evidence is lacking in this case). We have elucidated that the anticodons of tRNAs deciphering these nonuniversal codons (tRNATrp for UGA, tRNAMet for AUA, tRNAAsn for AAA, and tRNASer and tRNAGly for AGA/AGG) are all modified; tRNATrp has 5-carboxymethylaminomethyluridine or 5-taurinomethyluridine, tRNAMet has 5-formylcytidine or 5-taurinomethyluridine, tRNASer has 7-methylguanosine and tRNAGly has 5-taurinomethyluridine in their anticodon wobble position, and tRNAAsn has pseudouridine in the anticodon second position. This review aims to clarify the structural relationship between these nonuniversal codons and the corresponding tRNA anticodons including modified nucleosides and to speculate on the possible mechanisms for explaining the evolutional changes of these nonuniversal codons in the course of animal evolution.
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Affiliation(s)
- Kimitsuna Watanabe
- Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
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Cheng R, Zheng X, Lin X, Yang J, Li Q. Determination of the complete mitochondrial DNA sequence of Octopus minor. Mol Biol Rep 2011; 39:3461-70. [PMID: 21710247 DOI: 10.1007/s11033-011-1118-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 06/20/2011] [Indexed: 01/31/2023]
Abstract
In this study, we have determined the complete nucleotide sequence of the mitochondrial genome of Octopus minor. It is 15,974 nucleotide pairs and encodes 13 proteins, two ribosomal RNAs and 22 tRNAs of the mitochondrion's own protein synthesizing system. Seven of thirteen proteins are encoded by the H-strand, while the other six proteins, as well as the two ribosomal RNAs are encoded by the L-strand. The nucleotide composition of the proteins showed a nucleotide bias against G encoded by the H-strand, while they showed a nucleotide bias against A and C encoded by the L-strand. Two of the 13 protein coding genes of O. minor began with the unorthodox translation initiation codon ATA and all others use the standard ATG. In addition, six of thirteen mt proteins of O. minor have unambiguous termination codons. There are four cases where tRNA genes appear to overlap. The long noncoding region (LNCR) of O. minor was 930 nucleotides and no repeated sequences were found in this LNCR. The gene arrangements of O. minor showed remarkable similarity to that of O. ocellatus and O. vulgaris. Phylogenetic analysis demonstrated that O. minor appears as sister taxan to the monophyletic group combined by O. ocellatus and O. vulgaris, suggesting a relative distant genetic relationship between O. minor and the other two octopus species.
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Affiliation(s)
- Rubin Cheng
- Fisheries College, Ocean University of China, Qingdao, 266003, China
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20
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Yu H, Li Q. Mutation and selection on the wobble nucleotide in tRNA anticodons in marine bivalve mitochondrial genomes. PLoS One 2011; 6:e16147. [PMID: 21267462 PMCID: PMC3022732 DOI: 10.1371/journal.pone.0016147] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 12/07/2010] [Indexed: 11/19/2022] Open
Abstract
Background Animal mitochondrial genomes typically encode one tRNA for each synonymous codon family, so that each tRNA anticodon essentially has to wobble to recognize two or four synonymous codons. Several factors have been hypothesized to determine the nucleotide at the wobble site of a tRNA anticodon in mitochondrial genomes, such as the codon-anticodon adaptation hypothesis, the wobble versatility hypothesis, the translation initiation and elongation conflict hypothesis, and the wobble cost hypothesis. Principal Findings In this study, we analyzed codon usage and tRNA anticodon wobble sites of 29 marine bivalve mitochondrial genomes to evaluate features of the wobble nucleotides in tRNA anticodons. The strand-specific mutation bias favors G and T on the H strand in all the 29 marine bivalve mitochondrial genomes. A bias favoring G and T is also visible in the third codon positions of protein-coding genes and the wobble sites of anticodons, rejecting that codon usage bias drives the wobble sites of tRNA anticodons or tRNA anticodon bias drives the evolution of codon usage. Almost all codon families (98.9%) from marine bivalve mitogenomes support the wobble versatility hypothesis. There are a few interesting exceptions involving tRNATrp with an anticodon CCA fixed in Pectinoida species, tRNASer with a GCU anticodon fixed in Mytiloida mitogenomes, and the uniform anticodon CAU of tRNAMet translating the AUR codon family. Conclusions/Significance These results demonstrate that most of the nucleotides at the wobble sites of tRNA anticodons in marine bivalve mitogenomes are determined by wobble versatility. Other factors such as the translation initiation and elongation conflict, and the cost of wobble translation may contribute to the determination of the wobble nucleotide in tRNA anticodons. The finding presented here provides valuable insights into the previous hypotheses of the wobble nucleotide in tRNA anticodons by adding some new evidence.
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Affiliation(s)
- Hong Yu
- Fisheries College, Ocean University of China, Qingdao, Shandong, China
| | - Qi Li
- Fisheries College, Ocean University of China, Qingdao, Shandong, China
- * E-mail:
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21
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Yu H, Li Q. Mutation and selection on the wobble nucleotide in tRNA anticodons in marine bivalve mitochondrial genomes. PLoS One 2011; 6:e16147. [PMID: 21267462 DOI: 10.1371/journal.pone0016147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 12/07/2010] [Indexed: 05/26/2023] Open
Abstract
BACKGROUND Animal mitochondrial genomes typically encode one tRNA for each synonymous codon family, so that each tRNA anticodon essentially has to wobble to recognize two or four synonymous codons. Several factors have been hypothesized to determine the nucleotide at the wobble site of a tRNA anticodon in mitochondrial genomes, such as the codon-anticodon adaptation hypothesis, the wobble versatility hypothesis, the translation initiation and elongation conflict hypothesis, and the wobble cost hypothesis. PRINCIPAL FINDINGS In this study, we analyzed codon usage and tRNA anticodon wobble sites of 29 marine bivalve mitochondrial genomes to evaluate features of the wobble nucleotides in tRNA anticodons. The strand-specific mutation bias favors G and T on the H strand in all the 29 marine bivalve mitochondrial genomes. A bias favoring G and T is also visible in the third codon positions of protein-coding genes and the wobble sites of anticodons, rejecting that codon usage bias drives the wobble sites of tRNA anticodons or tRNA anticodon bias drives the evolution of codon usage. Almost all codon families (98.9%) from marine bivalve mitogenomes support the wobble versatility hypothesis. There are a few interesting exceptions involving tRNA(Trp) with an anticodon CCA fixed in Pectinoida species, tRNA(Ser) with a GCU anticodon fixed in Mytiloida mitogenomes, and the uniform anticodon CAU of tRNA(Met) translating the AUR codon family. CONCLUSIONS/SIGNIFICANCE These results demonstrate that most of the nucleotides at the wobble sites of tRNA anticodons in marine bivalve mitogenomes are determined by wobble versatility. Other factors such as the translation initiation and elongation conflict, and the cost of wobble translation may contribute to the determination of the wobble nucleotide in tRNA anticodons. The finding presented here provides valuable insights into the previous hypotheses of the wobble nucleotide in tRNA anticodons by adding some new evidence.
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Affiliation(s)
- Hong Yu
- Fisheries College, Ocean University of China, Qingdao, Shandong, China
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22
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The human mitochondrial tRNAMet: structure/function relationship of a unique modification in the decoding of unconventional codons. J Mol Biol 2010; 406:257-74. [PMID: 21168417 DOI: 10.1016/j.jmb.2010.11.042] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 11/18/2010] [Accepted: 11/22/2010] [Indexed: 11/21/2022]
Abstract
Human mitochondrial mRNAs utilize the universal AUG and the unconventional isoleucine AUA codons for methionine. In contrast to translation in the cytoplasm, human mitochondria use one tRNA, hmtRNA(Met)(CAU), to read AUG and AUA codons at both the peptidyl- (P-), and aminoacyl- (A-) sites of the ribosome. The hmtRNA(Met)(CAU) has a unique post-transcriptional modification, 5-formylcytidine, at the wobble position 34 (f(5)C(34)), and a cytidine substituting for the invariant uridine at position 33 of the canonical U-turn in tRNAs. The structure of the tRNA anticodon stem and loop domain (hmtASL(Met)(CAU)), determined by NMR restrained molecular modeling, revealed how the f(5)C(34) modification facilitates the decoding of AUA at the P- and the A-sites. The f(5)C(34) defined a reduced conformational space for the nucleoside, in what appears to have restricted the conformational dynamics of the anticodon bases of the modified hmtASL(Met)(CAU). The hmtASL(Met)(CAU) exhibited a C-turn conformation that has some characteristics of the U-turn motif. Codon binding studies with both Escherichia coli and bovine mitochondrial ribosomes revealed that the f(5)C(34) facilitates AUA binding in the A-site and suggested that the modification favorably alters the ASL binding kinetics. Mitochondrial translation by many organisms, including humans, sometimes initiates with the universal isoleucine codons AUU and AUC. The f(5)C(34) enabled P-site codon binding to these normally isoleucine codons. Thus, the physicochemical properties of this one modification, f(5)C(34), expand codon recognition from the traditional AUG to the non-traditional, synonymous codons AUU and AUC as well as AUA, in the reassignment of universal codons in the mitochondria.
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Yang JS, Nagasawa H, Fujiwara Y, Tsuchida S, Yang WJ. The complete mitogenome of the hydrothermal vent crab Gandalfus yunohana (Crustacea: Decapoda: Brachyura): a link between the Bythograeoidea and Xanthoidea. ZOOL SCR 2010. [DOI: 10.1111/j.1463-6409.2010.00442.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Watanabe K. Unique features of animal mitochondrial translation systems. The non-universal genetic code, unusual features of the translational apparatus and their relevance to human mitochondrial diseases. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:11-39. [PMID: 20075606 PMCID: PMC3417567 DOI: 10.2183/pjab.86.11] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 11/17/2009] [Indexed: 05/17/2023]
Abstract
In animal mitochondria, several codons are non-universal and their meanings differ depending on the species. In addition, the tRNA structures that decipher codons are sometimes unusually truncated. These features seem to be related to the shortening of mitochondrial (mt) genomes, which occurred during the evolution of mitochondria. These organelles probably originated from the endosymbiosis of an aerobic eubacterium into an ancestral eukaryote. It is plausible that these events brought about the various characteristic features of animal mt translation systems, such as genetic code variations, unusually truncated tRNA and rRNA structures, unilateral tRNA recognition mechanisms by aminoacyl-tRNA synthetases, elongation factors and ribosomes, and compensation for RNA deficits by enlarged proteins. In this article, we discuss molecular mechanisms for these phenomena. Finally, we describe human mt diseases that are caused by modification defects in mt tRNAs.
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Affiliation(s)
- Kimitsuna Watanabe
- Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo, Japan.
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25
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Yokogawa T, Kitamura Y, Nakamura D, Ohno S, Nishikawa K. Optimization of the hybridization-based method for purification of thermostable tRNAs in the presence of tetraalkylammonium salts. Nucleic Acids Res 2009; 38:e89. [PMID: 20040572 PMCID: PMC2847242 DOI: 10.1093/nar/gkp1182] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We found that both tetramethylammonium chloride (TMA-Cl) and tetra-ethylammonium chloride (TEA-Cl), which are used as monovalent cations for northern hybridization, drastically destabilized the tertiary structures of tRNAs and enhanced the formation of tRNA*oligoDNA hybrids. These effects are of great advantage for the hybridization-based method for purification of specific tRNAs from unfractionated tRNA mixtures through the use of an immobilized oligoDNA complementary to the target tRNA. Replacement of NaCl by TMA-Cl or TEA-Cl in the hybridization buffer greatly improved the recovery of a specific tRNA, even from unfractionated tRNAs derived from a thermophile. Since TEA-Cl destabilized tRNAs more strongly than TMA-Cl, it was necessary to lower the hybridization temperature at the sacrifice of the purity of the recovered tRNA when using TEA-Cl. Therefore, we propose two alternative protocols, depending on the desired properties of the tRNA to be purified. When the total recovery of the tRNA is important, hybridization should be carried out in the presence of TEA-Cl. However, if the purity of the recovered tRNA is important, TMA-Cl should be used for the hybridization. In principle, this procedure for tRNA purification should be applicable to any small-size RNA whose gene sequence is already known.
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Affiliation(s)
- Takashi Yokogawa
- Department of Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
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Takemoto C, Spremulli LL, Benkowski LA, Ueda T, Yokogawa T, Watanabe K. Unconventional decoding of the AUA codon as methionine by mitochondrial tRNAMet with the anticodon f5CAU as revealed with a mitochondrial in vitro translation system. Nucleic Acids Res 2009; 37:1616-27. [PMID: 19151083 PMCID: PMC2655697 DOI: 10.1093/nar/gkp001] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mitochondrial (mt) tRNAMet has the unusual modified nucleotide 5-formylcytidine (f5C) in the first position of the anticodon. This tRNA must translate both AUG and AUA as methionine. By constructing an in vitro translation system from bovine liver mitochondria, we examined the decoding properties of the native mt tRNAMet carrying f5C in the anticodon compared to a transcript that lacks the modification. The native mt Met-tRNA could recognize both AUA and AUG codons as Met, but the corresponding synthetic tRNAMet lacking f5C (anticodon CAU), recognized only the AUG codon in both the codon-dependent ribosomal binding and in vitro translation assays. Furthermore, the Escherichia coli elongator tRNAMetm with the anticodon ac4CAU (ac4C = 4-acetylcytidine) and the bovine cytoplasmic initiator tRNAMet (anticodon CAU) translated only the AUG codon for Met on mt ribosome. The codon recognition patterns of these tRNAs were the same on E. coli ribosomes. These results demonstrate that the f5C modification in mt tRNAMet plays a crucial role in decoding the nonuniversal AUA codon as Met, and that the genetic code variation is compensated by a change in the tRNA anticodon, not by a change in the ribosome. Base pairing models of f5C-G and f5C-A based on the chemical properties of f5C are presented.
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Affiliation(s)
- Chie Takemoto
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
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27
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Lusic H, Gustilo EM, Vendeix FAP, Kaiser R, Delaney MO, Graham WD, Moye VA, Cantara WA, Agris PF, Deiters A. Synthesis and investigation of the 5-formylcytidine modified, anticodon stem and loop of the human mitochondrial tRNAMet. Nucleic Acids Res 2008; 36:6548-57. [PMID: 18927116 PMCID: PMC2582600 DOI: 10.1093/nar/gkn703] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Human mitochondrial methionine transfer RNA (hmtRNA(Met)(CAU)) has a unique post-transcriptional modification, 5-formylcytidine, at the wobble position-34 (f(5)C(34)). The role of this modification in (hmtRNA(Met)(CAU)) for the decoding of AUA, as well as AUG, in both the peptidyl- and aminoacyl-sites of the ribosome in either chain initiation or chain elongation is still unknown. We report the first synthesis and analyses of the tRNA's anticodon stem and loop domain containing the 5-formylcytidine modification. The modification contributes to the tRNA's anticodon domain structure, thermodynamic properties and its ability to bind codons AUA and AUG in translational initiation and elongation.
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Affiliation(s)
- Hrvoje Lusic
- Department of Chemistry, Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695 and Dharmacon, 2650 Crescent Drive #100, Lafayette, CO 80026, USA
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Yang JS, Nagasawa H, Fujiwara Y, Tsuchida S, Yang WJ. The complete mitochondrial genome sequence of the hydrothermal vent galatheid crab Shinkaia crosnieri (Crustacea: Decapoda: Anomura): a novel arrangement and incomplete tRNA suite. BMC Genomics 2008; 9:257. [PMID: 18510775 PMCID: PMC2442616 DOI: 10.1186/1471-2164-9-257] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2008] [Accepted: 05/30/2008] [Indexed: 11/10/2022] Open
Abstract
Background Metazoan mitochondrial genomes usually consist of the same 37 genes. Such genes contain useful information for phylogenetic analyses and evolution modelling. Although complete mitochondrial genomes have been determined for over 1,000 animals to date, hydrothermal vent species have, thus far, remained excluded due to the scarcity of collected specimens. Results The mitochondrial genome of the hydrothermal vent galatheid crab Shinkaia crosnieri is 15,182 bp in length, and is composed of 13 protein-coding genes, two ribosomal RNA genes and only 18 transfer RNA genes. The total AT content of the genome, as is typical for decapods, is 72.9%. We identified a non-coding control region of 327 bp according to its location and AT-richness. This is the smallest control region discovered in crustaceans so far. A mechanism of cytoplasmic tRNA import was addressed to compensate for the four missing tRNAs. The S. crosnieri mitogenome exhibits a novel arrangement of mitochondrial genes. We investigated the mitochondrial gene orders and found that at least six rearrangements from the ancestral pancrustacean (crustacean + hexapod) pattern have happened successively. The codon usage, nucleotide composition and bias show no substantial difference with other decapods. Phylogenetic analyses using the concatenated nucleotide and amino acid sequences of the 13 protein-coding genes prove consistent with the previous classification based upon their morphology. Conclusion The present study will supply considerable data of use for both genomic and evolutionary research on hydrothermal vent ecosystems. The mitochondrial genetic characteristics of decapods are sustained in this case of S. crosnieri despite the absence of several tRNAs and a number of dramatic rearrangements. Our results may provide evidence for the immigrating hypothesis about how vent species originate.
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Affiliation(s)
- Jin-Shu Yang
- Institute of Cell Biology and Genetics, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang 310058, PR China.
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Jones TE, Brown CL, Geslain R, Alexander RW, Ribas de Pouplana L. An operational RNA code for faithful assignment of AUG triplets to methionine. Mol Cell 2008; 29:401-7. [PMID: 18280245 DOI: 10.1016/j.molcel.2007.12.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/26/2007] [Accepted: 12/03/2007] [Indexed: 12/01/2022]
Abstract
The assignment of AUG codons to methionine remains a central question of the evolution of the genetic code. We have unveiled a strategy for the discrimination among tRNAs containing CAU (AUG-decoding) anticodons. Mycoplasma penetrans methionyl-tRNA synthetase can directly differentiate between tRNA(Ile)(CAU) and tRNA(Met)(CAU) transcripts (a recognition normally achieved through the modification of anticodon bases). This discrimination mechanism is based only on interactions with the acceptor stems of tRNA(Ile)(CAU) and tRNA(Met)(CAU). Thus, in certain species, the fidelity of translation of methionine codons requires a discrimination mechanism that is independent of the information contained in the anticodon.
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Affiliation(s)
- Thomas E Jones
- Barcelona Institute for Research in Biomedicine, Barcelona Science Park, C/Samitier 1-5, Barcelona 08015, Catalonia, Spain
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30
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OHAMA T, INAGAKI Y, BESSHO Y, OSAWA S. Evolving genetic code. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2008; 84:58-74. [PMID: 18941287 PMCID: PMC2805505 DOI: 10.2183/pjab.84.58] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Accepted: 12/28/2007] [Indexed: 05/26/2023]
Abstract
In 1985, we reported that a bacterium, Mycoplasma capricolum, used a deviant genetic code, namely UGA, a "universal" stop codon, was read as tryptophan. This finding, together with the deviant nuclear genetic codes in not a few organisms and a number of mitochondria, shows that the genetic code is not universal, and is in a state of evolution. To account for the changes in codon meanings, we proposed the codon capture theory stating that all the code changes are non-disruptive without accompanied changes of amino acid sequences of proteins. Supporting evidence for the theory is presented in this review. A possible evolutionary process from the ancient to the present-day genetic code is also discussed.
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Affiliation(s)
- Takeshi OHAMA
- Kochi University of Technology, Department of Environmental System Engineering, 185 Miyanokuchi, Tosayamada-Cho, Kaimi-Shi, Kochi 782-8502, Japan
| | - Yuji INAGAKI
- University of Tsukuba, Center for Computational Sciences, Institute of Biological Sciences, Tsukuba, Ibaraki 305-8577, Japan
| | - Yoshitaka BESSHO
- Genomic Sciences Center, Yokohama Institute, RIKEN, 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Syozo OSAWA
- 1003, 2-4-7, Ushita-Asahi, Higashi-ku, Hiroshima 732-0067, Japan
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31
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Sengupta S, Yang X, Higgs PG. The mechanisms of codon reassignments in mitochondrial genetic codes. J Mol Evol 2007; 64:662-88. [PMID: 17541678 PMCID: PMC1894752 DOI: 10.1007/s00239-006-0284-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 03/07/2007] [Indexed: 11/26/2022]
Abstract
Many cases of nonstandard genetic codes are known in mitochondrial genomes. We carry out analysis of phylogeny and codon usage of organisms for which the complete mitochondrial genome is available, and we determine the most likely mechanism for codon reassignment in each case. Reassignment events can be classified according to the gain-loss framework. The “gain” represents the appearance of a new tRNA for the reassigned codon or the change of an existing tRNA such that it gains the ability to pair with the codon. The “loss” represents the deletion of a tRNA or the change in a tRNA so that it no longer translates the codon. One possible mechanism is codon disappearance (CD), where the codon disappears from the genome prior to the gain and loss events. In the alternative mechanisms the codon does not disappear. In the unassigned codon mechanism, the loss occurs first, whereas in the ambiguous intermediate mechanism, the gain occurs first. Codon usage analysis gives clear evidence of cases where the codon disappeared at the point of the reassignment and also cases where it did not disappear. CD is the probable explanation for stop to sense reassignments and a small number of reassignments of sense codons. However, the majority of sense-to-sense reassignments cannot be explained by CD. In the latter cases, by analysis of the presence or absence of tRNAs in the genome and of the changes in tRNA sequences, it is sometimes possible to distinguish between the unassigned codon and the ambiguous intermediate mechanisms. We emphasize that not all reassignments follow the same scenario and that it is necessary to consider the details of each case carefully.
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Affiliation(s)
- Supratim Sengupta
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 Canada
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 3J5 Canada
| | - Xiaoguang Yang
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 Canada
| | - Paul G. Higgs
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 Canada
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Takai K. Classification of the possible pairs between the first anticodon and the third codon positions based on a simple model assuming two geometries with which the pairing effectively potentiates the decoding complex. J Theor Biol 2006; 242:564-80. [PMID: 16764891 DOI: 10.1016/j.jtbi.2006.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 02/11/2006] [Accepted: 04/11/2006] [Indexed: 11/24/2022]
Abstract
Crick's wobble theory states that some specific pairs between the bases at the first position of the anticodon (position 34) and the third position of the codon (position III) are allowed and the others are disallowed during the correct codon recognition. However, later researches have shown that the pairing rule, or the wobble rule, is different from the supposed one. Despite the continuing efforts including computer-aided model building studies and analyses of three-dimensional structures in the crystals of the ribosomes, the structural backgrounds of the wobble rule are still unclear. Here, I classify the possible pairs into 6 classes according to the increases accompanying the formation of the pairs in the potential productivity of the decoding complex on the basis of a simple model that was originally proposed previously and is refined here. In the model, the conformation with the base at position 34 displaced toward the minor groove side from the position for the Watson-Crick pairs is supposed to be equivalent to the conformation with the Watson-Crick pairs. It is also reasoned and supposed that some weak pairs may sometimes be allowed depending on the structural context. It is demonstrated that most of the experimental results reported so far are consistent with the model. I discuss on which experimental facts can be reasoned with the model and which need further explanations. I expect that the model will be a good basis for further understanding of the wobble rule and its structural backgrounds.
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Affiliation(s)
- Kazuyuki Takai
- Cell-free Science and Technology Research Center, Ehime University, 3, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
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33
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Boore JL. The complete sequence of the mitochondrial genome of Nautilus macromphalus (Mollusca: Cephalopoda). BMC Genomics 2006; 7:182. [PMID: 16854241 PMCID: PMC1544340 DOI: 10.1186/1471-2164-7-182] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 07/19/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mitochondria contain small genomes that are physically separate from those of nuclei. Their comparison serves as a model system for understanding the processes of genome evolution. Although complete mitochondrial genome sequences have been reported for more than 600 animals, the taxonomic sampling is highly biased toward vertebrates and arthropods, leaving much of the diversity yet uncharacterized. RESULTS The mitochondrial genome of the bellybutton nautilus, Nautilus macromphalus, a cephalopod mollusk, is 16,258 nts in length and 59.5% A+T, both values that are typical of animal mitochondrial genomes. It contains the 37 genes that are almost universally found in animal mtDNAs, with 15 on one DNA strand and 22 on the other. The arrangement of these genes can be derived from that of the distantly related Katharina tunicata (Mollusca: Polyplacophora) by a switch in position of two large blocks of genes and transpositions of four tRNA genes. There is strong skew in the distribution of nucleotides between the two strands, and analysis of this yields insight into modes of transcription and replication. There is an unusual number of non-coding regions and their function, if any, is not known; however, several of these demark abrupt shifts in nucleotide skew, and there are several identical sequence elements at these junctions, suggesting that they may play roles in transcription and/or replication. One of the non-coding regions contains multiple repeats of a tRNA-like sequence. Some of the tRNA genes appear to overlap on the same strand, but this could be resolved if the polycistron were cleaved at the beginning of the downstream gene, followed by polyadenylation of the product of the upstream gene to form a fully paired structure. CONCLUSION Nautilus macromphalus mtDNA contains an expected gene content that has experienced few rearrangements since the evolutionary split between cephalopods and polyplacophorans. It contains an unusual number of non-coding regions, especially considering that these otherwise often are generated by the same processes that produce gene rearrangements. The skew in nucleotide composition between the two strands is strong and associated with the direction of transcription in various parts of the genomes, but a comparison with K. tunicata implies that mutational bias during replication also plays a role. This appears to be yet another case where polyadenylation of mitochondrial tRNAs restores what would otherwise be an incomplete structure.
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Affiliation(s)
- Jeffrey L Boore
- Evolutionary Genomics Program, DOE Joint Genome Institute and Lawrence Berkeley National Laboratory, Walnut Creek, CA 94598, USA.
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Abstract
Many modified genetic codes are found in specific genomes in which one or more codons have been reassigned to a different amino acid from that in the canonical code. We present a new framework for codon reassignment that incorporates two previously proposed mechanisms (codon disappearance and ambiguous intermediate) and introduces two further mechanisms (unassigned codon and compensatory change). Our theory is based on the observation that reassignment involves a gain and a loss. The loss could be the deletion or loss of function of a tRNA or release factor. The gain could be the gain of a new type of tRNA or the gain of function of an existing tRNA due to mutation or base modification. The four mechanisms are distinguished by whether the codon disappears from the genome during the reassignment and by the order of the gain and loss events. We present simulations of the gain-loss model showing that all four mechanisms can occur within the same framework as the parameters are varied. We investigate the way the frequencies of the mechanisms are influenced by selection strengths, the number of codons undergoing reassignment, directional mutation pressure, and selection for reduced genome size.
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Affiliation(s)
- Supratim Sengupta
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
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35
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Gissi C, Iannelli F, Pesole G. Complete mtDNA of Ciona intestinalis reveals extensive gene rearrangement and the presence of an atp8 and an extra trnM gene in ascidians. J Mol Evol 2004; 58:376-89. [PMID: 15114417 DOI: 10.1007/s00239-003-2559-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Accepted: 10/23/2003] [Indexed: 11/25/2022]
Abstract
The complete mitochondrial genome (mtDNA) of the model organism Ciona intestinalis (Urochordata, Ascidiacea) has been amplified by long-PCR using specific primers designed on putative mitochondrial transcripts identified from publicly available mitochondrial-like expressed sequence tags. The C. intestinalis mtDNA encodes 39 genes: 2 rRNAs, 13 subunits of the respiratory complexes, including ATPase subunit 8 ( atp8), and 24 tRNAs, including 2 tRNA-Met with anticodons 5'-UAU-3'and 5'-CAU-3', respectively. All genes are transcribed from the same strand. This gene content seems to be a common feature of ascidian mtDNAs, as we have verified the presence of a previously undetected atp8 and of two trnM genes in the two other sequenced ascidian mtDNAs. Extensive gene rearrangement has been found in C. intestinalis with respect not only to the common Vertebrata/Cephalochordata/Hemichordata gene organization but also to other ascidian mtDNAs, including the cogeneric Ciona savignyi. Other features such as the absence of long noncoding regions, the shortness of rRNA genes, the low GC content (21.4%), and the absence of asymmetric base distribution between the two strands suggest that this genome is more similar to those of some protostomes than to deuterostomes.
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Affiliation(s)
- Carmela Gissi
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università di Milano, Via Celoria 26, 20133 Milan, Italy
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Grosjean H, Björk GR. Enzymatic conversion of cytidine to lysidine in anticodon of bacterial tRNAIle – an alternative way of RNA editing. Trends Biochem Sci 2004; 29:165-8. [PMID: 15124629 DOI: 10.1016/j.tibs.2004.02.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Henri Grosjean
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique, 1 avenue de la Terrasse, F-91198 Gif-sur-Yvette, France.
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37
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Agris PF. Decoding the genome: a modified view. Nucleic Acids Res 2004; 32:223-38. [PMID: 14715921 PMCID: PMC384350 DOI: 10.1093/nar/gkh185] [Citation(s) in RCA: 270] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Revised: 12/02/2003] [Accepted: 12/02/2003] [Indexed: 11/12/2022] Open
Abstract
Transfer RNA's role in decoding the genome is critical to the accuracy and efficiency of protein synthesis. Though modified nucleosides were identified in RNA 50 years ago, only recently has their importance to tRNA's ability to decode cognate and wobble codons become apparent. RNA modifications are ubiquitous. To date, some 100 different posttranslational modifications have been identified. Modifications of tRNA are the most extensively investigated; however, many other RNAs have modified nucleosides. The modifications that occur at the first, or wobble position, of tRNA's anticodon and those 3'-adjacent to the anticodon are of particular interest. The tRNAs most affected by individual and combinations of modifications respond to codons in mixed codon boxes where distinction of the third codon base is important for discriminating between the correct cognate or wobble codons and the incorrect near-cognate codons (e.g. AAA/G for lysine versus AAU/C asparagine). In contrast, other modifications expand wobble codon recognition, such as U*U base pairing, for tRNAs that respond to multiple codons of a 4-fold degenerate codon box (e.g. GUU/A/C/G for valine). Whether restricting codon recognition, expanding wobble, enabling translocation, or maintaining the messenger RNA, reading frame modifications appear to reduce anticodon loop dynamics to that accepted by the ribosome. Therefore, we suggest that anticodon stem and loop domain nucleoside modifications allow a limited number of tRNAs to accurately and efficiently decode the 61 amino acid codons by selectively restricting some anticodon-codon interactions and expanding others.
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Affiliation(s)
- Paul F Agris
- Department of Molecular and Structural Biochemistry, 128 Polk Hall, Campus Box 7622, North Carolina State University, Raleigh, NC 27695-7622, USA.
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38
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Hanada T, Suzuki T, Yokogawa T, Takemoto-Hori C, Sprinzl M, Watanabe K. Translation ability of mitochondrial tRNAsSer with unusual secondary structures in an in vitro translation system of bovine mitochondria. Genes Cells 2001; 6:1019-30. [PMID: 11737263 DOI: 10.1046/j.1365-2443.2001.00491.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Metazoan mitochondrial (mt) tRNAs are structurally quite different from the canonical cloverleaf secondary structure. The mammalian mt tRNASerGCU for AGY codons (Y = C or U) lacks the entire D arm, whereas tRNASerUGA for UCN codons (N = A, G, C or U) has an extended anti-codon stem. It has been a long-standing problem to prove experimentally how these tRNAsSer work in the mt translation system. RESULTS To solve the above-mentioned problem, we examined their translational abilities in an in vitro bovine mitochondrial translation system using transcripts of altered tRNASer analogues derived from bovine mitochondria. Both tRNASer analogues had almost the same ability to form ternary complexes with mt EF-Tu and GTP. The D-arm-lacking tRNASer GCU analogue had considerably lower translational activity than the tRNASerUGA analogue and produced mostly short oligopeptides, up to a tetramer. In addition, tRNASerGCU analogue was disfavoured by the ribosome when other tRNAs capable of decoding the cognate codon were available. CONCLUSION Both mt tRNASerGCU and tRNASerUGA analogues with unusual secondary structure were found to be capable of translation on the ribosome. However, the tRNASerGCU analogue has some molecular disadvantage on the ribosome, which probably derives from the lack of a D arm.
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Affiliation(s)
- T Hanada
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Lim VI, Curran JF. Analysis of codon:anticodon interactions within the ribosome provides new insights into codon reading and the genetic code structure. RNA (NEW YORK, N.Y.) 2001; 7:942-957. [PMID: 11453067 PMCID: PMC1370147 DOI: 10.1017/s135583820100214x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Although the decoding rules have been largely elucidated, the physical-chemical reasons for the "correctness" of codon:anticodon duplexes have never been clear. In this work, on the basis of the available data, we propose that the correct codon:anticodon duplexes are those whose formation and interaction with the ribosomal decoding center are not accompanied by uncompensated losses of hydrogen and ionic bonds. Other factors such as proofreading, base-base stacking and aminoacyl-tRNA concentration contribute to the efficiency and accuracy of aminoacyl-tRNA selection, and certainly these factors are important; but we suggest that analyses of hydrogen and ionic bonding alone provides a robust first-order approximation of decoding accuracy. Thus our model can simplify predictions about decoding accuracy and error. The model can be refined with data, but is already powerful enough to explain all of the available data on decoding accuracy. Here we predict which duplexes should be considered correct, which duplexes are responsible for virtually all misreading, and we suggest an evolutionary scheme that gave rise to the mixed boxes of the genetic code.
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Affiliation(s)
- V I Lim
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow
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40
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Knight RD, Freeland SJ, Landweber LF. Rewiring the keyboard: evolvability of the genetic code. Nat Rev Genet 2001; 2:49-58. [PMID: 11253070 DOI: 10.1038/35047500] [Citation(s) in RCA: 264] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The genetic code evolved in two distinct phases. First, the 'canonical' code emerged before the last universal ancestor; subsequently, this code diverged in numerous nuclear and organelle lineages. Here, we examine the distribution and causes of these secondary deviations from the canonical genetic code. The majority of non-standard codes arise from alterations in the tRNA, with most occurring by post-transcriptional modifications, such as base modification or RNA editing, rather than by substitutions within tRNA anticodons.
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Affiliation(s)
- R D Knight
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.
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Affiliation(s)
- R D Knight
- Department of Ecology and Evolutionary Biology, Princeton University, New Jersey 08544, USA.
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