Aminoacylation catalyzed by aminoacyl-tRNA synthetases (aaRSs) involves covalent linkage of amino acids with their cognate tRNAs and represents the initiating step in the complex process of translation. However, the mechanism of amino acid selection and editing by eukaryotic cytoplasmic ThrRSs remains to be elucidated. Now, a new study from Chinese Academy of Sciences provides the first comprehensive elucidation of the translational fidelity control mechanism of eukaryotic Threonyl-tRNA synthetase (ThrRS).
Dr. ZHOU Xiaolong and other researchers in Prof. WANG Enduo's lab at the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences systematically analyzed the evolution of cytoplasmic ThrRSs from eukaryotes, role of the eukaryote-specific N-extension of ThrRSs, and mis-activation of Ser, Val, Cys, Gly, Ala by S. cerevisiae ThrRS (ScThrRS).
They clarified the editing mechanism of ScThrRS and quantified the relative contribution of various editing pathways in total editing activity, identified the crucial nucleic acid and amino acid determinants for the editing reaction, constructed the first yeast thrS gene knockout strain and used it as a platform for the in vivo genetic assays. They also found yeast cells are 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 entitled "Translational fidelity maintenance preventing Ser mis-incorporation at Thr codon in protein from eukaryote" was published online in Nucleic Acids Research on October 23, 2012. The work was funded by the National Natural Science Foundation of China, Ministry of Science and Technology and Chinese Academy of Sciences. CONTACT:
WANG Enduo
Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences,
Shanghai, China
Phone: 86-21-54921241
E-mail: edwang@sibcb.ac.cn 
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Beijing, China (100864)
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