title: Translational fidelity maintenance preventing Ser mis-incorporation at Thr codon in protein from eukaryote.
abstract: Aminoacyl-tRNA synthetase (aaRS) catalyzes the first step of protein synthesis, producing aminoacyl-tRNAs as building blocks. Eukaryotic aaRS differs from its prokaryotic counterpart in terminal extension or insertion. Moreover, the editing function of aaRSs is an indispensable checkpoint excluding non-cognate amino acids at a given codon and ensuring overall translational fidelity. We found higher eukaryotes encode two cytoplasmic threonyl-tRNA synthetases (ThrRSs) with difference in N-terminus. The longer isoform is more closely related to the ThrRSs of higher eukaryotes than to those of lower eukaryotes. A yeast strain was generated to include deletion of the thrS gene encoding ThrRS. Combining in vitro biochemical and in vivo genetic data, ThrRSs from eukaryotic cytoplasm were systematically analyzed, and role of the eukaryotic cytoplasmic ThrRS-specific N-terminal extension was elucidated. Furthermore, the mechanisms of aminoacylation and editing activity mediated by Saccharomyces cerevisiae ThrRS (ScThrRS) were clarified. Interestingly, yeast cells were tolerant of variation at the editing active sites of ScThrRS without significant Thr-to-Ser conversion in the proteome even under significant environmental stress, implying checkpoints downstream of aminoacylation to provide a further quality control mechanism for the yeast translation system. This study has provided the first comprehensive elucidation of the translational fidelity control mechanism of eukaryotic ThrRS.
authors.affiliation: Center for RNA research, 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 200031, China.
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Zhou
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Ruan
authors.forename: Qian
authors.initials: Q
authors.lastname: Huang
authors.forename: Min
authors.initials: M
authors.lastname: Tan
authors.forename: En-Duo
authors.initials: ED
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000926:Anticodon / Q000737:chemistry; D001120:Arginine / Q000737:chemistry; D001483:Base Sequence; D003062:Codon; D003593:Cytoplasm / Q000201:enzymology; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D017393:RNA Editing; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012363:RNA, Transfer, Thr / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016415:Sequence Alignment; D012694:Serine / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism*; D013914:Threonine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D046249:Transfer RNA Aminoacylation; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000926:Anticodon; D003062:Codon; D007527:Isoenzymes; D012363:RNA, Transfer, Thr; D013912:Threonine; D014443:Tyrosine; D012694:Serine; D012343:RNA, Transfer; D001120:Arginine; D013914:Threonine-tRNA Ligase