The 2 Å crystal structure of leucyl-tRNA synthetase and its complex with a leucyl-adenylate analogue
The 2 Å crystal structure of leucyl-tRNA synthetase and its complex with a leucyl-adenylate analogue
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DOI：
10.1093/emboj/19.10.2351
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发表时间：
2000-05-15
期刊：
影响因子：
11.4
通讯作者：
Tukalo, M
中科院分区：
文献类型：
--
作者：
Cusack, S;Yaremchuk, A;Tukalo, M
亮氨酸、异亮氨酸和谷氨酸trna合成酶是密切相关的大单体I类合成酶。每一个都包含一个类似于200个残基的同源插入域，这被认为允许它们水解（“编辑”）同源tRNA，这些tRNA已经被化学上相似但非同源的氨基酸错配。我们在2.0埃的分辨率下描述了来自嗜热菌Thermus thermophilus的第一个亮基- trna合成酶的晶体结构。其整体结构与异亮基trna合成酶相似，只是假定的编辑结构域插入在初级结构的不同位置。这种特征是原核细胞样亮基trna合成酶所特有的，因为存在一种新的附加灵活插入结构域。天然酶和配合物与亮氨酸和亮氨酸类似物的比较表明，结合亮氨酸-腺苷酸的腺苷部分会导致氨基酸激活和腺苷酸紧密结合所需的活性位点发生显着的构象变化。这些变化被传播到酶的更远的区域，导致一个更有序的结构，为随后的氨基酰化和/或编辑步骤做好准备。
Leucyl-, isoleucyl- and valyl-tRNA synthetases are closely related large monomeric class I synthetases. Each contains a homologous insertion domain of similar to 200 residues, which is thought to permit them to hydrolyse ('edit') cognate tRNA that has been mischarged with a chemically similar but non-cognate amino acid. We describe the first crystal structure of a leucyl-tRNA synthetase, from the hyperthermophile Thermus thermophilus, at 2.0 Angstrom resolution. The overall architecture is similar to that of isoleucyl-tRNA synthetase, except that the putative editing domain is inserted at a different position in the primary structure. This feature is unique to prokaryote-like leucyl-tRNA synthetases, as is the presence of a novel additional flexibly inserted domain. Comparison of native enzyme and complexes with leucine and a leucyladenylate analogue shows that binding of the adenosine moiety of leucyl-adenylate causes significant conformational changes in the active site required for amino acid activation and tight binding of the adenylate. These changes are propagated to more distant regions of the enzyme, leading to a significantly more ordered structure ready for the subsequent aminoacylation and/or editing steps.