Kinetic discrimination of tRNA identity by the conserved motif 2 loop of a class II aminoacyl-tRNA synthetase
Kinetic discrimination of tRNA identity by the conserved motif 2 loop of a class II aminoacyl-tRNA synthetase
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DOI：
10.1016/j.molcel.2007.01.015
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发表时间：
2007-02-23
期刊：
影响因子：
16
通讯作者：
Francklyn, Christopher S.
中科院分区：
文献类型：
--
作者：
Guth, Ethan C.;Francklyn, Christopher S.
通过同源氨酰-tRNA 合成酶选择 tRNA 对于确保蛋白质合成的保真度至关重要。虽然组成 tRNA 身份集的核苷酸已很容易被识别，但它们在氨酰化基本步骤中的具体作用却知之甚少。通过使用 tRNA H 及其同源氨酰基-tRNA 合成酶中的突变体进行快速动力学分析，研究了 tRNA 同一性在氨酰化中的作用。虽然 tRNA 反密码子的突变优先影响初始复合物形成的热力学，但 tRNA 合成酶的受体茎或保守基序 2 环的突变对氨酰基转移施加了特定的动力学阻断，并减少了 tRNA 介导的氨基酸激活的动力学控制。 tRNA 同一性的机制基础类似于 DNA 聚合酶和核糖体的保真度控制，其反应也要求高精度。
The selection of tRNAs by their cognate aminoacyl-tRNA synthetases is critical for ensuring the fidelity of protein synthesis. While nucleotides that comprise tRNA identity sets have been readily identified, their specific role in the elementary steps of aminoacylation is poorly understood. By use of a rapid kinetics analysis employing mutants in tRNA H's and its cognate aminoacyl-tRNA synthetase, the role of tRNA identity in aminoacylation was investigated. While mutations in the tRNA anticodon preferentially affected the thermodynamics of initial complex formation, mutations in the acceptor stem or the conserved motif 2 loop of the tRNA synthetase imposed a specific kinetic block on aminoacyl transfer and decreased tRNA-mediated kinetic control of amino acid activation. The mechanistic basis of tRNA identity is analogous to fidelity control by DNA polymerases and the ribosome, whose reactions also demand high accuracy.