Sco proteins are involved in electron transfer processes
Sco proteins are involved in electron transfer processes
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DOI：
10.1007/s00775-010-0735-x
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发表时间：
2011-03-01
影响因子：
3
通讯作者：
Wang, Shenlin
中科院分区：
文献类型：
--
作者：
Banci, Lucia;Bertini, Ivano;Wang, Shenlin
Sco蛋白广泛存在于真核生物和许多原核生物中。它们具有类似硫氧还蛋白的折叠，并通过 CXXXC 基序和保守的 His 配体结合单个铜 (I) 或铜 (II) 离子，具有紧密和弱亲和力。它们作为铜伴侣和/或硫氧还蛋白参与细胞色素 c 氧化酶 Cu-A 位点的组装。在这项工作中，我们对恶臭假单胞菌中与典型电子转移分子（即细胞色素 c）自然融合的 Sco 结构域进行了结构表征。硫氧还蛋白样Sco结构域不结合铜(II)，以弱亲和力结合铜(I)而不涉及保守的His，并且具有由硫氧还蛋白活性和将细胞色素c结构域的铜(II)还原为铜(I)、铁(III)还原为铁(II)的能力组成的氧化还原性质。这些发现表明，His 配体配位是在硫氧还蛋白样折叠中引入金属伴侣功能的区分因素，通常负责电子转移过程。对恶臭假单胞菌与真核 Sco 蛋白的 Sco 结构域的比较结构分析揭示了影响 Sco 蛋白中紧亲和力与弱亲和力铜结合位点形成的结构决定因素。
Sco proteins are widespread in eukaryotic and in many prokaryotic organisms. They have a thioredoxin-like fold and bind a single copper(I) or copper(II) ion through a CXXXC motif and a conserved His ligand, with both tight and weak affinities. They have been implicated in the assembly of the Cu-A site of cytochrome c oxidase as copper chaperones and/or thioredoxins. In this work we have structurally characterized a Sco domain which is naturally fused with a typical electron transfer molecule, i.e., cytochrome c, in Pseudomonas putida. The thioredoxin-like Sco domain does not bind copper(II), binds copper(I) with weak affinity without involving the conserved His, and has redox properties consisting of a thioredoxin activity and of the ability of reducing copper(II) to copper(I), and iron(III) to iron(II) of the cytochrome c domain. These findings indicate that the His ligand coordination is the discriminating factor for introducing a metallochaperone function in a thioredoxin-like fold, typically responsible for electron transfer processes. A comparative structural analysis of the Sco domain from P. putida versus eukaryotic Sco proteins revealed structural determinants affecting the formation of a tight-affinity versus a weak-affinity copper binding site in Sco proteins.