Crystal structure of non-redox regulated SSADH from Escherichia coli
Crystal structure of non-redox regulated SSADH from Escherichia coli
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DOI：
10.1016/j.bbrc.2010.01.014
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发表时间：
2010-01-29
影响因子：
3.1
通讯作者：
Kim, Kyung-Jin
中科院分区：
文献类型：
--
作者：
Ahn, Jae-Woo;Kim, Yeon-Gil;Kim, Kyung-Jin
SSADH参与了GABA降解的最后一步，在人类线粒体基质中将SSA转化为琥珀酸，已知其活性通过催化环氧化还原开关调节来调节。我们给出了EcSSADH的晶体结构，揭示了EcSSADH的催化环不同于人类SSADH的催化环，不会随着环境氧化还原状态的变化而发生二硫键介导的结构变化。随后利用重组蛋白进行的氧化还原改变实验证实了该蛋白的非氧化还原调节。详细的结构分析表明，连接环(β15-β16)构象的不同导致了EcSSADH中连接环和催化环之间形成了一个水分子介导的氢键网络，使EcSSADH的催化环比人SSADH的催化环更加刚性。该蛋白的胞浆定位和GABA分流的细胞功能可能导致了该蛋白的非氧化还原调节机制。(C)2010 Elsevier Inc.保留所有权利。
SSADH is involved in the final step of GABA degradation, converting SSA to succinic acid in the human mitochondrial matrix, and its activity is known to be regulated via 'redox-switch modulation' of the catalytic loop. We present the crystal structure of EcSSADH, revealing that the catalytic loop of EcSSADH, unlike that of human SSADH, does not undergo disulfide bond-mediated structural changes upon changes of environmental redox status. Subsequent redox change experiments using recombinant proteins confirm the non-redox regulation of this protein. Detailed structural analysis shows that a difference in the conformation of the connecting loop (beta 15-beta 16) causes the formation of a water molecule-mediated hydrogen bond network between the connecting loop and the catalytic loop in EcSSADH, making the catalytic loop of EcSSADH more rigid compared to that of human SSADH. The cytosolic localization of EcSSADH and the cellular function of the GABA shunt in E. coli might result in the non-redox mediated regulatory mechanisms of the Protein. (C) 2010 Elsevier Inc. All rights reserved.