title: A minimalist mitochondrial threonyl-tRNA synthetase exhibits tRNA-isoacceptor specificity during proofreading.
abstract: Yeast mitochondria contain a minimalist threonyl-tRNA synthetase (ThrRS) composed only of the catalytic core and tRNA binding domain but lacking the entire editing domain. Besides the usual tRNA(Thr)2, some budding yeasts, such as Saccharomyces cerevisiae, also contain a non-canonical tRNA(Thr)1 with an enlarged 8-nucleotide anticodon loop, reprograming the usual leucine CUN codons to threonine. This raises interesting questions about the aminoacylation fidelity of such ThrRSs and the possible contribution of the two tRNA(Thr)s during editing. Here, we found that, despite the absence of the editing domain, S. cerevisiae mitochondrial ThrRS (ScmtThrRS) harbors a tRNA-dependent pre-transfer editing activity. Remarkably, only the usual tRNA(Thr)2 stimulated pre-transfer editing, thus, establishing the first example of a synthetase exhibiting tRNA-isoacceptor specificity during pre-transfer editing. We also showed that the failure of tRNA(Thr)1 to stimulate tRNA-dependent pre-transfer editing was due to the lack of an editing domain. Using assays of the complementation of a ScmtThrRS gene knockout strain, we showed that the catalytic core and tRNA binding domain of ScmtThrRS co-evolved to recognize the unusual tRNA(Thr)1. In combination, the results provide insights into the tRNA-dependent editing process and suggest that tRNA-dependent pre-transfer editing takes place in the aminoacylation catalytic core.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Ruan
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Zhi-Peng
authors.initials: ZP
authors.lastname: Fang
authors.affiliation: School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, 200031 Shanghai, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China.
authors.forename: Ru-Juan
authors.initials: RJ
authors.lastname: Liu
authors.affiliation: Architecture et Réactivité de l'ARN, Université de Strasbourg, UPR9002 CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg, France.
authors.forename: Gilbert
authors.initials: G
authors.lastname: Eriani
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, China School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, 200031 Shanghai, China edwang@sibs.ac.cn.
authors.forename: En-Duo
authors.initials: ED
authors.lastname: Wang
mesh_terms: D000926:Anticodon; D019143:Evolution, Molecular; D017353:Gene Deletion; D008928:Mitochondria / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D012363:RNA, Transfer, Thr / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013914:Threonine-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046249:Transfer RNA Aminoacylation
chemical_list: D000926:Anticodon; D012363:RNA, Transfer, Thr; D013914:Threonine-tRNA Ligase