Global Conformational Change Associated with the Two-step Reaction Catalyzed by Escherichia coli Lipoate-Protein Ligase A
Global Conformational Change Associated with the Two-step Reaction Catalyzed by Escherichia coli Lipoate-Protein Ligase A
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DOI：
10.1074/jbc.m109.078717
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发表时间：
2010-03-26
影响因子：
4.8
通讯作者：
Taniguchi, Hisaaki
中科院分区：
文献类型：
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作者：
Fujiwara, Kazuko;Maita, Nobuo;Taniguchi, Hisaaki
硫辛酸蛋白连接酶 A (LplA) 通过两步反应催化硫辛酸与硫辛酸依赖性酶的附着：首先是硫辛酸腺苷酸化反应，其次是硫辛酸转移反应。我们之前确定了大肠杆菌 LplA 的未配体形式和与硫辛酸的二元复合物的晶体结构（Fujiwara, K.、Toma, S.、Okamura-Ikeda, K.、Motokawa, Y.、Nakakawa, A. 和 Taniguchi, H. (2005) J Biol. Chem. 280, 33645-33651）。在这里，我们报道了两种新的LplA结构，LplA.lipoyl-5'-AMP和LplA.octyl-5'-AMP.apoH-蛋白质复合物，它们分别代表硫辛酸腺苷化后中间状态和硫辛酸转移前中间状态。这些结构展示了硫辛酸腺苷酸化反应完成后的三个大规模构象变化：腺苷酸结合环和硫辛酸结合环的运动以维持硫辛酸-5'-AMP反应中间体以及C端结构域旋转约180度。这些变化是 LplA 适应脱辅基蛋白进行第二次反应的先决条件。 Lys(133) 残基在硫辛酸腺苷酸化和硫辛酸转移反应中起着重要作用。基于结构和动力学数据，我们提出了一种由构象变化驱动的反应机制。
Lipoate-protein ligase A (LplA) catalyzes the attachment of lipoic acid to lipoate-dependent enzymes by a two-step reaction: first the lipoate adenylation reaction and, second, the lipoate transfer reaction. We previously determined the crystal structure of Escherichia coli LplA in its unliganded form and a binary complex with lipoic acid (Fujiwara, K., Toma, S., Okamura-Ikeda, K., Motokawa, Y., Nakagawa, A., and Taniguchi, H. (2005) J Biol. Chem. 280, 33645-33651). Here, we report two new LplA structures, LplA.lipoyl-5'-AMP and LplA.octyl-5'-AMP.apoH-protein complexes, which represent the post-lipoate adenylation intermediate state and the pre-lipoate transfer intermediate state, respectively. These structures demonstrate three large scale conformational changes upon completion of the lipoate adenylation reaction: movements of the adenylate-binding and lipoate-binding loops to maintain the lipoyl-5'-AMP reaction intermediate and rotation of the C-terminal domain by about 180 degrees. These changes are prerequisites for LplA to accommodate apoprotein for the second reaction. The Lys(133) residue plays essential roles in both lipoate adenylation and lipoate transfer reactions. Based on structural and kinetic data, we propose a reaction mechanism driven by conformational changes.