中文摘要：本研究发现，与典型的苏氨酰-tRNA合成酶相比，支原体不同类型苏氨酰-tRNA合成酶在结构组成和编辑活性位点方面存在很大差异。支原体可移性苏氨酰-tRNA合成酶天然缺失N1结构域，表现出高效的转录后编辑活性；而丝状支原体苏氨酰-tRNA合成酶包含了一个N1结构域和退化的N2结构域，则不具备编辑活性。只有具有编辑活性的苏氨酰-tRNA合成酶才能保证酿酒酵母ScmtThrRS基因敲除株（Sc Δ thrS）的正常生长，因而Sc Δ thrS是研究细菌性苏氨酰-tRNA合成酶体外编辑活性的优秀材料。基于对N1结构域或者缺失现象的认识，研究进一步揭示了N1结构域唯一的绝对保守残基的重要功能，即通过介导大肠杆菌苏氨酰-tRNA合成酶N1-N2区域的互作来调节编辑活性。该研究揭示了不同苏氨酰-tRNA合成酶对翻译质量的控制及N1结构域在翻译保真性方面的重要作用。
外文摘要：Translational fidelity mediated by aminoacyl-tRNA synthetases ensures the generation of the correct aminoacyl-tRNAs, which is critical for most species. Threonyl-tRNA synthetase (ThrRS) contains multiple domains, including an N2 editing domain. Of the ThrRS domains, N1 is the last to be assigned a function. Here, we found that ThrRSs from Mycoplasma species exhibit differences in their domain composition and editing active sites compared with the canonical ThrRSs. The Mycoplasma mobile ThrRS, the first example of a ThrRS naturally lacking the N1 domain, displays efficient post-transfer editing activity. In contrast, the Mycoplasma capricolum ThrRS, which harbors an N1 domain and a degenerate N2 domain, is editing-defective. Only editing-capable ThrRSs were able to support the growth of a yeast thrS deletion strain (Sc Delta thrS), thus suggesting that Sc Delta thrS is an excellent tool for studying the in vivo editing of introduced bacterial ThrRSs. On the basis of the presence or absence of an N1 domain, we further revealed the crucial importance of the only absolutely conserved residue within the N1 domain in regulating editing by mediating an N1-N2 domain interaction in Escherichia coli ThrRS. Our results reveal the translational quality control of various ThrRSs and the role of the N1 domain in translational fidelity.
外文关键词：GENETIC-CODE； PROTEIN-BIOSYNTHESIS； AMINOACYLATION；DOMAIN； MISTRANSLATION； TRNA(LEU)； COMPLEX；YEAST； DISCRIMINATION； RECOGNITION
作者：Zhou XL；Chen Y；Fang ZP等
作者单位：中国科学院上海生命科学研究院生物化学与细胞生物学研究所
期刊名称：JOURNAL OF BIOLOGICAL CHEMISTRY
期刊影响因子：4.258
出版年份：2016
出版刊次：9
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