X-ray structure of a blue-copper nitrite reductase in two crystal forms. The nature of the copper sites, mode of substrate binding and recognition by redox partner
X-ray structure of a blue-copper nitrite reductase in two crystal forms. The nature of the copper sites, mode of substrate binding and recognition by redox partner
复制标题
DOI：
10.1006/jmbi.1998.2007
复制
发表时间：
1998-09-18
影响因子：
5.6
通讯作者：
Hasnain, SS
中科院分区：
文献类型：
--
作者：
Dodd, FE;Van Beeumen, J;Hasnain, SS
反硝化作用是原核生物维持全球氮循环的主要步骤之一。反硝化细菌在此过程中使用两种完全不同的酶，一种基于血红素cd 1辅基，另一种基于1型-2型Cu中心。含铜亚硝酸盐还原酶（NiRs）又分为蓝色NiRs和绿色NiRs，它们分别被认为是天青蛋白和假天青蛋白的氧化还原伴侣。从Alcaligenes xylosoxidans（AxNiR）的蓝色亚硝酸盐还原酶的晶体结构中提出的氧化六方晶形式和底物结合的斜方晶形式，分别为2.1埃和2.8埃的分辨率。AxNiR的完整氨基酸序列已通过常规化学分析确定。AxNiR的3埃结构已经发表，其中建模是基于另一种蓝色NiR的序列。六角形形式的较高分辨率以及正确的序列允许与绿色NiRs的晶体结构进行详细比较。有一个显着的差异，在两个子组之间的整体表面电荷分布，提供了一个整洁的结构解释其不同的反应性，以pseudoazurin或azurin和支持的观点，电子转移通过复杂的形成。对1型Cu位点（负责颜色的位点）的详细检查揭示了几个细微的差异，包括S-met的0.7埃的横向位移。2型铜网站的结构，并发生在基板结合的催化机制方面的变化进行了讨论。2型铜网站碳酸酐酶和超氧化物歧化酶的催化铜网站的催化锌网站的相似性重新检查的高分辨率（2.1埃）的结构。(C)北京：科学出版社.
Denitrification is one of the main steps of the global nitrogen cycle that is sustained by prokaryotic organisms. Denitrifying bacteria use two entirely different enzymes in this process, one based on haem cd1 prosthetic groups and the other on type 1-type 2 Cu centres. Copper-containing nitrite reductases (NiRs) are sub-divided into blue and green NiRs, which are respectively thought to be redox partners of azurins and pseudo-azurins. Crystallographic structures of the blue nitrite reductase from Alcaligenes xylosoxidans (AxNiR) are presented in the oxidised hexagonal form and the substrate-bound orthorhombic form to 2.1 Angstrom and 2.8 Angstrom resolution, respectively. The complete amino acid sequence of AxNiR has been determined by conventional chemical analysis. A 3 Angstrom structure-of AxNiR has been published where the modelling was based on the sequence of another blue NiR. The higher resolution of the hexagonal form together with the correct sequence allows a detailed comparison with the crystallographic structures of the green NiRs. There is a striking difference in the overall surface charge distribution between the two sub-groups, providing a neat structural explanation for their different reactivities to pseudoazurin or azurin and supporting the view that electron transfer proceeds via complex formation. A detailed examination of the type-1 Cu site, the site responsible for the colour, reveals several subtle differences, including a lateral displacement of 0.7 Angstrom for S-met. The structure of the type-2 Cu site, and changes that occur upon substrate binding are discussed in terms of the catalytic mechanism. The similarity of the type 2 Cu site to the catalytic Zn site in carbonic anhydrase and the catalytic Cu site of superoxide dismutase is re-examined in view of the high-resolution (2.1 Angstrom) structure.(C) 1998 Academic Press.