Three-dimensional structure of AzoR from Escherichia coli -: An oxidereductase conserved in microorganisms
Three-dimensional structure of AzoR from Escherichia coli -: An oxidereductase conserved in microorganisms
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DOI：
10.1074/jbc.m513345200
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发表时间：
2006-07-21
影响因子：
4.8
通讯作者：
Tanokura, Masaru
中科院分区：
文献类型：
--
作者：
Ito, Kosuke;Nakanishi, Masayuki;Tanokura, Masaru
偶氮还原酶（AzoR）在1.8埃和2.2埃分辨率下用FMN络合物测定了两种不同晶型的晶体结构。AzoR是从大肠杆菌中分离出来的氧化还原酶，是一种负责偶氮化合物降解的蛋白质。该酶是一种依赖于fmn的nadh -偶氮还原酶，通过乒乓机制催化偶氮基团的还原裂解。该结构表明，AzoR在同二聚体状态下作用，形成两个相同的催化位点，这两个单体都有贡献。结构表明，AzoR的每个单体具有类似黄毒毒素的结构，没有明确的整体氨基酸序列同源性。两种不同晶体形式的结构叠加揭示了构象变化，并提出了容纳不同尺寸衬底的机制。此外，将活性位点结构与NQO1与底物配合的活性位点结构进行比较，为AzoR可能的底物结合机制提供了线索。
The crystal structure of AzoR (azoreductase) has been determined in complex with FMN for two different crystal forms at 1.8 and 2.2 angstrom resolution. AzoR is an oxidoreductase isolated from Escherichia coli as a protein responsible for the degradation of azo compounds. This enzyme is an FMN-dependent NADH-azoreductase and catalyzes the reductive cleavage of azo groups by a ping-pong mechanism. The structure suggests that AzoR acts in a homodimeric state forming the two identical catalytic sites to which both monomers contribute. The structure revealed that each monomer of AzoR has a flavodoxin-like structure, without the explicit overall amino acid sequence homology. Superposition of the structures from the two different crystal forms revealed the conformational change and suggested a mechanism for accommodating substrates of different size. Furthermore, comparison of the active site structure with that of NQO1 complexed with substrates provides clues to the possible substrate-binding mechanism of AzoR.