Insights into the respiratory electron transfer pathway from the structure of nitrate reductase A
Insights into the respiratory electron transfer pathway from the structure of nitrate reductase A
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DOI：
10.1038/nsb969
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发表时间：
2003-09-01
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影响因子：
--
通讯作者：
Strynadka, NCJ
中科院分区：
文献类型：
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作者：
Bertero, MG;Rothery, RA;Strynadka, NCJ
兼性厌氧菌大肠杆菌能够通过合成适当的呼吸酶和还原酶来组装特定的呼吸链，以响应特定底物的可用性。在厌氧条件下，在硝酸盐存在下，E.大肠杆菌合成细胞质膜结合的喹啉-硝酸盐氧化还原酶（硝酸盐还原酶A; NarGHI），其将硝酸盐还原为亚硝酸盐并形成产生质子动力的氧化还原环的一部分。我们在这里提出了NarGHI的晶体结构，分辨率为1.9埃。NarGHI结构确定了氧化还原活性辅基的数量、配位方案和环境、钼原子的独特配位、开放双环形式的双（蝶呤鸟嘌呤二核苷酸）（Mo-bisMGD）辅因子在催化机制中的作用的第一个结构证据以及膜锚亚基的新折叠。我们的研究结果提供了基本的分子细节，了解质子动力产生的氧化还原回路的机制。
The facultative anaerobe Escherichia coli is able to assemble specific respiratory chains by synthesis of appropriate dehydrogenases and reductases in response to the availability of specific substrates. Under anaerobic conditions in the presence of nitrate, E. coli synthesizes the cytoplasmic membrane-bound quinol-nitrate oxidoreductase ( nitrate reductase A; NarGHI), which reduces nitrate to nitrite and forms part of a redox loop generating a proton-motive force. We present here the crystal structure of NarGHI at a resolution of 1.9 Angstrom. The NarGHI structure identifies the number, coordination scheme and environment of the redox-active prosthetic groups, a unique coordination of the molybdenum atom, the first structural evidence for the role of an open bicyclic form of the molybdo-bis( molybdopterin guanine dinucleotide) (Mo-bisMGD) cofactor in the catalytic mechanism and a novel fold of the membrane anchor subunit. Our findings provide fundamental molecular details for understanding the mechanism of proton-motive force generation by a redox loop.