Redox properties of the disulfide bond of human Cu,Zn superoxide dismutase and the effects of human glutaredoxin 1.
Redox properties of the disulfide bond of human Cu,Zn superoxide dismutase and the effects of human glutaredoxin 1.
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DOI：
10.1042/bj20120075
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发表时间：
2012-08-15
期刊：
影响因子：
--
通讯作者：
Outten CE
中科院分区：
文献类型：
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作者：
Bouldin SD;Darch MA;Hart PJ;Outten CE
人Cu，Zn超氧化物歧化酶1（hSOD 1）中的分子内二硫键对维持蛋白质的稳定性和四级结构起着关键作用。在引起家族性肌萎缩侧索硬化症（ALS）的SOD 1突变形式中，这种二硫键更容易受到化学还原的影响，这可能导致二聚体的不稳定和聚集。在hSOD 1成熟过程中，二硫键的形成由铜分子伴侣CCS 1催化。先前在酵母中的研究表明，酵母谷胱甘肽（GSH）/谷氧还蛋白氧化还原系统在不存在CCS 1的情况下促进hSOD 1二硫化物的还原。在此，我们进一步探讨hSOD 1，GSH，和谷氧还蛋白之间的相互作用，以提供hSOD 1二硫化物的氧化还原动力学和热力学的机制洞察。我们证明，人谷氧还蛋白1（hGrx 1）使用一个单硫醇机制，以减少hSOD 1二硫化物，和GSH/hGrx 1系统减少ALS突变体SOD 1在一个更快的速度比WT hSOD 1。然而，氧化还原电位测量表明，与WT hSOD 1相比，ALS突变体中二硫化物的热力学稳定性并不一致。此外，金属辅因子的存在不影响二硫化物氧化还原电位。总体而言，这些研究表明，WT与ALS突变体hSOD 1的GSH/hGrx 1反应速率的差异，而不是hSOD 1二硫键的固有热力学稳定性，可能导致ALS突变体hSOD 1的致病性更大。
The intramolecular disulfide bond in human Cu,Zn superoxide dismutase 1 (hSOD1) plays a key role in maintaining the protein’s stability and quaternary structure. In mutant forms of SOD1 that cause familial amyotrophic lateral sclerosis (ALS), this disulfide bond is more susceptible to chemical reduction, which may lead to destabilization of the dimer and aggregation. During hSOD1 maturation, disulfide formation is catalyzed by the copper chaperone CCS1. Previous studies in yeast demonstrate that the yeast glutathione (GSH)/glutaredoxin redox system promotes reduction of the hSOD1 disulfide in the absence of CCS1. Herein, we further probe the interaction between hSOD1, GSH, and glutaredoxins to provide mechanistic insight into the redox kinetics and thermodynamics of the hSOD1 disulfide. We demonstrate that human glutaredoxin 1 (hGrx1) uses a monothiol mechanism to reduce the hSOD1 disulfide, and the GSH/hGrx1 system reduces ALS mutant SOD1 at a faster rate than WT hSOD1. However, redox potential measurements demonstrate that the thermodynamic stability of the disulfide is not consistently lower in ALS mutants compared to WT hSOD1. Furthermore, the presence of the metal cofactors does not influence the disulfide redox potential. Overall, these studies suggest that differences in the GSH/hGrx1 reaction rate with WT vs. ALS mutant hSOD1 and not the inherent thermodynamic stability of the hSOD1 disulfide bond may contribute to the greater pathogenicity of ALS mutant hSOD1.