Structure of the AlaX-M trans-editing enzyme from Pyrococcus horikoshii
Structure of the AlaX-M trans-editing enzyme from Pyrococcus horikoshii
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DOI：
10.1107/s090744490605640x
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发表时间：
2007-03-01
期刊：
影响因子：
--
通讯作者：
Yokoyama, Shigeyuki
中科院分区：
文献类型：
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作者：
Fukunaga, Ryuya;Yokoyama, Shigeyuki
丙氨酰-tRNA合成酶（AlaRS）的编辑结构域通过水解（编辑）不正确的产物Ser-tRNA（Ala）和Gly-tRNA（Ala）（顺式编辑）而有助于高保真氨酰化。AlaX蛋白与AlaRS的编辑结构域具有序列同源性。存在三种类型的AlaX蛋白，具有不同数量的氨基酸残基（AlaX-S、AlaX-M和AlaX-L）。在本报告中，来自Pyrococcus horikoshii的AlaX-M显示出脱酰化Ser-tRNA（Ala）和Gly-tRNA（Ala）（反式编辑）。已在2.7埃分辨率下测定了P. horikoshii AlaX-M的晶体结构。AlaX-M由N-末端结构域（N-domain）和C-末端结构域（C-domain）组成。锌离子由C-结构域中的保守锌结合簇配位，这被预期为酶活性位点。富含甘氨酸的基序由N-结构域中的连续保守甘氨酸残基组成，形成环（“富含甘氨酸的环”）。富含甘氨酸的环位于活性位点附近，并且可能参与底物识别和/或催化。
The editing domain of alanyl-tRNA synthetase (AlaRS) contributes to high-fidelity aminoacylation by hydrolyzing (editing) the incorrect products Ser-tRNA(Ala) and Gly-tRNA(Ala) (cis-editing). The AlaX protein shares sequence homology to the editing domain of AlaRS. There are three types of AlaX proteins, with different numbers of amino-acid residues (AlaX-S, AlaX-M and AlaX-L). In this report, AlaX-M from Pyrococcus horikoshii is shown to deacylate Ser-tRNA(Ala) and Gly-tRNA(Ala) (trans-editing). The crystal structure of P. horikoshii AlaX-M has been determined at 2.7 angstrom resolution. AlaX-M consists of an N-terminal domain (N-domain) and a C-terminal domain (C-domain). A zinc ion is coordinated by the conserved zinc-binding cluster in the C-domain, which is expected to be the enzymatic active site. The glycine-rich motif, consisting of successive conserved glycine residues in the N-domain, forms a loop (the 'glycine-rich loop'). The glycine-rich loop is located near the active site and may be involved in substrate recognition and/or catalysis.