Structural basis for the oxidation of thiosulfate by a sulfur cycle enzyme
Structural basis for the oxidation of thiosulfate by a sulfur cycle enzyme
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DOI：
10.1093/emboj/cdf566
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发表时间：
2002-11-01
期刊：
影响因子：
11.4
通讯作者：
Hemmings, AM
中科院分区：
文献类型：
--
作者：
Bamford, VA;Bruno, S;Hemmings, AM
还原无机硫化合物被许多细菌用作光合或呼吸电子传递链的电子供体。这种代谢是地球化学硫循环的关键组成部分。SoxAX蛋白是参与硫代硫酸盐氧化的异二聚体C型细胞色素。来自光合细菌Rhodovulum sulfidophilum的SoxAX的晶体结构已经在氧化状态下以1.75埃分辨率和在连二亚硫酸盐还原状态下以1.5埃分辨率得到解决，这为硫代硫酸盐的酶促氧化提供了第一个结构见解。SoxAX活性位点包含一个具有前所未有的半胱氨酸过硫化物（半胱氨酸硫烷）配位的血红素。这种不寻常的翻译后修饰也出现在硫转移酶（例如罗德岛酶）中。有趣的是，这种酶与SoxAX共享进一步的活性位点特征，例如相邻的保守精氨酸残基和强正静电势。这些相似性使我们能够提出一种酶促硫代硫酸盐氧化的催化机制。原子坐标和实验结构因子已存放在PDB中，登录代码为1H31，1H32和1H33。
Reduced inorganic sulfur compounds are utilized by many bacteria as electron donors to photosynthetic or respiratory electron transport chains. This metabolism is a key component of the biogeochemical sulfur cycle. The SoxAX protein is a heterodimeric c-type cytochrome involved in thiosulfate oxidation. The crystal structures of SoxAX from the photosynthetic bacterium Rhodovulum sulfidophilum have been solved at 1.75 Angstrom resolution in the oxidized state and at 1.5 Angstrom resolution in the dithionite-reduced state, providing the first structural insights into the enzymatic oxidation of thiosulfate. The SoxAX active site contains a haem with unprecedented cysteine persulfide (cysteine sulfane) coordination. This unusual post-translational modification is also seen in sulfurtransferases such as rhodanese. Intriguingly, this enzyme shares further active site characteristics with SoxAX such as an adjacent conserved arginine residue and a strongly positive electrostatic potential. These similarities have allowed us to suggest a catalytic mechanism for enzymatic thiosulfate oxidation. The atomic coordinates and experimental structure factors have been deposited in the PDB with the accession codes 1H31, 1H32 and 1H33.