Large Conformational Changes of Insertion 3 in Human Glycyl-tRNA Synthetase (hGlyRS) during Catalysis
Large Conformational Changes of Insertion 3 in Human Glycyl-tRNA Synthetase (hGlyRS) during Catalysis
复制标题
人甘氨酰-tRNA 合成酶 (hGlyRS) 催化过程中插入 3 的大构象变化
DOI：
10.1074/jbc.m115.679126
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发表时间：
2016-03-11
影响因子：
4.8
通讯作者：
Xie, Wei
中科院分区：
文献类型：
--
作者：
Deng, Xiangyu;Qin, Xiangjing;Xie, Wei
甘氨酰-tRNA合成酶（GlyRS）是将甘氨酸共价连接至同源tRNA以进行翻译的酶。由于其非保守的四级结构，独特的物种特异性氨酰化特性以及在神经系统疾病中的非典型功能，它具有很大的研究兴趣，但这些都没有被完全理解。我们报告了两种晶体结构的人GlyRS变体，在自由形式和复杂的tRNA（甘氨酸）分别，并揭示了新的方面的甘氨酰化机制。我们发现，插入3在催化中的构象有很大的不同，它就像一个开关，完全打开，允许tRNA以交叉亚基的方式结合。蛋白质的灵活性得到分子动力学模拟以及酶活性测定的支持。生物物理和生物化学研究表明，人类GlyRS可能利用其灵活性实现传统功能（调节tRNA结合）和替代功能（在疾病中的作用）。
Glycyl-tRNA synthetase (GlyRS) is the enzyme that covalently links glycine to cognate tRNA for translation. It is of great research interest because of its nonconserved quaternary structures, unique species-specific aminoacylation properties, and noncanonical functions in neurological diseases, but none of these is fully understood. We report two crystal structures of human GlyRS variants, in the free form and in complex with tRNA(Gly) respectively, and reveal new aspects of the glycylation mechanism. We discover that insertion 3 differs considerably in conformation in catalysis and that it acts like a switch and fully opens to allow tRNA to bind in a cross-subunit fashion. The flexibility of the protein is supported by molecular dynamics simulation, as well as enzymatic activity assays. The biophysical and biochemical studies suggest that human GlyRS may utilize its flexibility for both the traditional function (regulate tRNA binding) and alternative functions (roles in diseases).