Mechanisms of the copper-dependent turnover of the copper chaperone for superoxide dismutase
Mechanisms of the copper-dependent turnover of the copper chaperone for superoxide dismutase
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DOI：
10.1074/jbc.m601580200
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发表时间：
2006-05-12
影响因子：
4.8
通讯作者：
Gitlin, JD
中科院分区：
文献类型：
--
作者：
Caruano-Yzermans, AL;Bartnikas, TB;Gitlin, JD
超氧化物歧化酶铜分子伴侣（CCS）是一种细胞内金属分子伴侣，用于将铜结合到必需的抗氧化酶铜/锌超氧化物歧化酶（SOD 1）中。营养研究表明，CCS的丰度与膳食和组织铜含量成反比。为了确定CCS的铜依赖性调节的机制，在用野生型或突变型CCS转染的CCS-/-成纤维细胞的代谢标记后，确定铜掺入SOD 1和SOD 1酶活性以及CCS丰度和半衰期。野生型CCS恢复了CCS-/-成纤维细胞中的SOD 1活性，并且这些细胞中这种伴侣蛋白的丰度与培养基中的铜含量成反比，表明CCS的铜依赖性调节完全是翻译后的。虽然突变研究表明CCS结构域I在这种铜依赖性调节中没有作用，但对结构域III中的CXC基序的类似分析揭示了这些半胱氨酸残基在介导CCS的铜依赖性周转中的关键作用。进一步的突变研究表明，这种CXC依赖性铜介导的CCS周转不依赖于铜向SOD 1的传递机制，包括CCS-SOD 1相互作用。总之，这些数据证明了决定CCS丰度的机制，其与铜递送至SOD 1的过程竞争，揭示了细胞内铜稳态的独特翻译后组分。
The copper chaperone for superoxide dismutase (CCS) is an intracellular metallochaperone required for incorporation of copper into the essential antioxidant enzyme copper/zinc superoxide dismutase (SOD1). Nutritional studies have revealed that the abundance of CCS is inversely proportional to the dietary and tissue copper content. To determine the mechanisms of copper-dependent regulation of CCS, copper incorporation into SOD1 and SOD1 enzymatic activity as well as CCS abundance and half-life were determined after metabolic labeling of CCS-/- fibroblasts transfected with wild-type or mutant CCS. Wild-type CCS restored SOD1 activity in CCS-/- fibroblasts, and the abundance of this chaperone in these cells was inversely proportional to the copper content of the media, indicating that copper-dependent regulation of CCS is entirely post-translational. Although mutational studies demonstrated no role for CCS Domain I in this copper-dependent regulation, similar analysis of the CXC motif in Domain III revealed a critical role for these cysteine residues in mediating copper-dependent turnover of CCS. Further mutational studies revealed that this CXC-dependent copper-mediated turnover of CCS is independent of the mechanisms of delivery of copper to SOD1 including CCS-SOD1 interaction. Taken together these data demonstrate a mechanism determining the abundance of CCS that is competitive with the process of copper delivery to SOD1, revealing a unique post- translational component of intracellular copper homeostasis.