Departments of Biochemistry and Chemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University , Waltham, Massachusetts 02454, United States.
Biochemistry. 2013 Sep 10;52(36):6145-50. doi: 10.1021/bi400613h. Epub 2013 Aug 26.
The metalloenzyme Cu/Zn-superoxide dismutase (SOD1) catalyzes the reduction of superoxide anions into molecular oxygen and hydrogen peroxide. Hydrogen peroxide can oxidize SOD1, resulting in aberrant protein conformational changes, disruption of SOD1 function, and DNA damage. Cells may have evolved mechanisms of regulation that prevent such oxidation. We observed that cysteinylation of cysteine 111 (Cys111) of SOD1 prevents oxidation by peroxide (DOI 10.1021/bi4006122 ). In this article, we characterize cysteinylated SOD1 using differential scanning fluorometry and X-ray crystallography. The stoichiometry of binding was one cysteine per SOD1 dimer, and there does not appear to be free volume for a second cysteine without disrupting the dimer interface. Much of the three-dimensional structure of SOD1 is unaffected by cysteinylation. However, local conformational changes are observed in the cysteinylated monomer that include changes in conformation of the electrostatic loop (loop VII; residues 133-144) and the dimer interface (loop VI; residues 102-115). In addition, our data shows how cysteinylation precludes oxidation of cysteine 111 and suggests possible cross-talk between the dimer interface and the electrostatic loop.
金属酶 Cu/Zn-超氧化物歧化酶 (SOD1) 催化超氧阴离子还原为分子氧和过氧化氢。过氧化氢可以氧化 SOD1，导致异常的蛋白质构象变化、SOD1 功能障碍和 DNA 损伤。细胞可能已经进化出调节机制来防止这种氧化。我们观察到 SOD1 上的半胱氨酸 111 (Cys111) 的半胱氨酸化可防止过氧化物氧化 (DOI 10.1021/bi4006122)。在本文中，我们使用差示扫描荧光法和 X 射线晶体学来表征半胱氨酸化的 SOD1。结合的化学计量比为每个 SOD1 二聚体一个半胱氨酸，并且似乎没有自由体积可以容纳第二个半胱氨酸而不破坏二聚体界面。SOD1 的大部分三维结构不受半胱氨酸化的影响。然而，在半胱氨酸化的单体中观察到局部构象变化，包括静电环 (loop VII；残基 133-144) 和二聚体界面 (loop VI；残基 102-115) 的构象变化。此外，我们的数据表明半胱氨酸化如何阻止半胱氨酸 111 的氧化，并提出二聚体界面和静电环之间可能存在交叉对话。
