Cocrystal Structures of Glycyl-tRNA Synthetase in Complex with tRNA Suggest Multiple Conformational States in Glycylation
Cocrystal Structures of Glycyl-tRNA Synthetase in Complex with tRNA Suggest Multiple Conformational States in Glycylation
复制标题
甘氨酰-tRNA 合成酶与 tRNA 复合物的共晶结构表明甘氨酰化存在多种构象状态
DOI：
10.1074/jbc.m114.557249
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发表时间：
2014-07-18
影响因子：
4.8
通讯作者：
Xie, Wei
中科院分区：
文献类型：
--
作者：
Qin, Xiangjing;Hao, Zhitai;Xie, Wei
氨酰-tRNA合成酶是一个古老的酶家族，其特异性地将tRNA分子与同源氨基酸结合用于蛋白质合成。甘氨酰-tRNA合成酶（GlyRS）由于其独特的四级结构和异常的电荷性质而成为最有趣的氨酰-tRNA合成酶之一。在过去的十年中，人类GlyRS（hGlyRS）的突变也被发现与腓骨肌萎缩症相关。然而，由于缺乏分子基础上的研究，对hGlyRS的传统和替代功能的机制知之甚少。在这项研究中，我们报告的晶体结构的野生型和突变hGlyRS与tRNA和小底物的复合物，并描述了在受体茎和反密码子环的关键tRNA身份元素的酶识别的分子细节。共晶结构表明，插入1和3一起工作的活性位点在一个合作的方式，以促进有效的底物结合。在甘氨酰化过程中，酶和tRNA分子都发生了显著的构象变化。基于晶体学和生物化学研究，提出了hGlyRS催化的多构象工作模型。这项研究提供了深入了解hGlyRS的催化途径，也可能有助于我们了解腓骨肌萎缩症。
Aminoacyl-tRNA synthetases are an ancient enzyme family that specifically charges tRNA molecules with cognate amino acids for protein synthesis. Glycyl-tRNA synthetase (GlyRS) is one of the most intriguing aminoacyl-tRNA synthetases due to its divergent quaternary structure and abnormal charging properties. In the past decade, mutations of human GlyRS (hGlyRS) were also found to be associated with Charcot-Marie-Tooth disease. However, the mechanisms of traditional and alternative functions of hGlyRS are poorly understood due to a lack of studies at the molecular basis. In this study we report crystal structures of wild type and mutant hGlyRS in complex with tRNA and with small substrates and describe the molecular details of enzymatic recognition of the key tRNA identity elements in the acceptor stem and the anticodon loop. The cocrystal structures suggest that insertions 1 and 3 work together with the active site in a cooperative manner to facilitate efficient substrate binding. Both the enzyme and tRNA molecules undergo significant conformational changes during glycylation. A working model of multiple conformations for hGlyRS catalysis is proposed based on the crystallographic and biochemical studies. This study provides insights into the catalytic pathway of hGlyRS and may also contribute to our understanding of Charcot-Marie-Tooth disease.