A redox switch in CopC: An intriguing copper trafficking protein that binds copper(I) and copper(II) at different sites
A redox switch in CopC: An intriguing copper trafficking protein that binds copper(I) and copper(II) at different sites
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DOI：
10.1073/pnas.0636904100
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发表时间：
2003-04-01
影响因子：
11.1
通讯作者：
Thompsett, AR
中科院分区：
文献类型：
--
作者：
Arnesano, F;Banci, L;Thompsett, AR
已发现来自假单胞菌的蛋白CopC能够在两个不同位点结合铜（I）和铜（II），一次占据一个或同时占据。已知该蛋白质由102个氨基酸组成，在现在发现与包括His-1、Glu-27、Asp-89和His-91的配位排列一致的位置结合铜（II）。本文报道了Cu（I）-CopC的全溶液结构分析。铜（I）位点由His-48和四个Met残基中的三个（40、43、46、51）构成，其聚集在Met富集区域中。这两个铜结合位点的特征在于通过扩展的X射线吸收精细结构研究。它们代表了蛋白质中铜的新的配位环境。这两个位置相距约30埃，对另一种氧化态的离子几乎没有亲和力。Cu（I）-CopC的氧化或Cu（II）-CopC的还原导致铜从一个位点迁移到另一个位点。在NMR和EXAFS研究中都观察到这种行为，表明CopC可以在由氧化还原开关激活的两个位点之间交换铜。CopC存在于革兰氏阴性菌的周质中，其中存在多铜氧化酶CopA，其可以调节铜的氧化还原状态。CopC和CopA编码在同一操纵子中，负责铜抗性。这些独特的和新颖的性能的CopC进行了讨论，就其相关的铜稳态。
The protein CopC from Pseudomonas syringae has been found capable of binding copper(I) and copper(II) at two different sites, occupied either one at a time or simultaneously. The protein, consisting of 102 amino acids, is known to bind copper(II) in a position that is now found consistent with a coordination arrangement including His-1, Glu-27, Asp-89, and His-91. A full solution structure analysis is reported here for Cu(I)-CopC. The copper(I) site is constituted by His-48 and three of the four Met residues (40, 43, 46, 51), which are clustered in a Met-rich region. Both copper binding sites have been characterized through extended x-ray absorption fine structure studies. They represent novel coordination environments for copper in proteins. The two sites are approximate to30 Angstrom far apart and have little affinity for the ion in the other oxidation state. Oxidation of Cu(I)-CopC or reduction of Cu(II)-CopC causes migration of copper from one site to the other. This behavior is observed both in NMR and EXAFS studies and indicates that CopC can exchange copper between two sites activated by a redox switch. CopC resides in the periplasm of Gram-negative bacteria where there is a multicopper oxidase, CopA, which may modulate the redox state of copper. CopC and CopA are coded in the same operon, responsible for copper resistance. These peculiar and novel properties of CopC are discussed with respect to their relevance for copper homeostasis.