Oxygen-induced maturation of SOD1: a key role for disulfide formation by the copper chaperone CCS
Oxygen-induced maturation of SOD1: a key role for disulfide formation by the copper chaperone CCS
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DOI：
10.1038/sj.emboj.7600276
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发表时间：
2004-07-21
期刊：
影响因子：
11.4
通讯作者：
O'Halloran, TV
中科院分区：
文献类型：
--
作者：
Furukawa, Y;Torres, AS;O'Halloran, TV
抗氧化酶铜，锌-超氧化物歧化酶（SOD 1）的区别是在真核细胞质溶胶中已知的最丰富的含二硫化物的蛋白质之一，然而，既不催化也不保守的二硫化物的生理作用是已知的。在这里，我们表明，酿酒酵母SOD 1的二硫键状态显着影响单体-二聚体平衡，与铜分子伴侣CCS的相互作用，以及酶本身的活性。二硫化物形成SOD 1的O-2是缓慢的，但大大加快了铜结合形式的CCS（铜CCS）在体内和体外，即使在过量的还原剂的存在下，一旦形成，这种二硫化物是动力学稳定的。生化分析表明，铜CCS促进半胱氨酸氧化和二硫键异构化的不成熟形式的酶的活性状态的逐步转换。未成熟形式的SOD 1最容易受到氧化损伤和聚集，这让人想起在肌萎缩侧索硬化症中观察到的情况。因此，Cu-CCS介导SOD 1中正确的二硫键形成对于调节酶活性和防止错误折叠或聚集是重要的。
The antioxidant enzyme Cu, Zn-superoxide dismutase (SOD1) has the distinction of being one of the most abundant disulfide-containing protein known in the eukaryotic cytosol; however, neither catalytic nor physiological roles for the conserved disulfide are known. Here we show that the disulfide status of Saccharomyces cerevisiae SOD1 significantly affects the monomer - dimer equilibrium, the interaction with the copper chaperone CCS, and the activity of the enzyme itself. Disulfide formation in SOD1 by O-2 is slow but is greatly accelerated by the Cu-bound form of CCS (Cu-CCS) in vivo and in vitro even in the presence of excess reductants; once formed, this disulfide is kinetically stable. Biochemical assays reveal that Cu-CCS facilitates Cys oxidation and disulfide isomerization in the stepwise conversion of the immature form of the enzyme to the active state. The immature form of SOD1 is most susceptible to oxidative insult and to aggregation reminiscent of that observed in amyotrophic lateral sclerosis. Thus Cu-CCS mediation of correct disulfide formation in SOD1 is important for regulation of enzyme activity and for prevention of misfolding or aggregation.