Instability of Superoxide Dismutase 1 of Drosophila in Mutants Deficient for Its Cognate Copper Chaperone
Instability of Superoxide Dismutase 1 of Drosophila in Mutants Deficient for Its Cognate Copper Chaperone
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DOI：
10.1074/jbc.m807131200
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发表时间：
2008-12-19
影响因子：
4.8
通讯作者：
Phillips, John P.
中科院分区：
文献类型：
--
作者：
Kirby, Kim;Jensen, Laran T.;Phillips, John P.
铜锌超氧化物歧化酶（SOD 1）在哺乳动物中主要通过铜分子伴侣（CCS）激活，在较小程度上通过未知性质的非CCS依赖性途径激活。在这项研究中，我们的特点是需要CCS激活SOD 1从果蝇。果蝇的CCS无效突变体（Ccs（n29 E））的创建和发现，在减少成年寿命，氧化应激超敏反应，和胞质乌头酸酶活性的损失方面，表型类似果蝇SOD 1无效突变体。然而，CCS无效苍蝇的表型不太严重，与一些CCS无关的果蝇SOD 1（dSOD 1）激活一致。然而，在Ccsn 29 E果蝇中未检测到SOD 1活性，这主要是由于SOD 1蛋白的显著丢失。相比之下，人SOD 1表达的CCS-空苍蝇是稳健的积极和救援的赤字在成年寿命和敏感性氧化应激。在酵母表达系统中也观察到dSOD 1对CCS的依赖性，其中dSOD 1多肽在无CCS（ccs 1 Delta）酵母中表现出不寻常的不稳定性。尽管如此，在ccs 1 Delta酵母中残留的dSOD 1多肽仍具有活性，这与CCS非依赖性激活一致。dSOD 1在ccs 1 Delta细胞中的稳定性很容易通过酵母或果蝇CCS的表达来恢复，这需要将铜插入酶中。酵母表达系统也显示了CCS的一些种属特异性。酵母SOD 1表现出对酵母CCS的偏好超过果蝇CCS，而dSOD 1被任一CCS分子完全激活。SOD 1的铜激活机制的这种变化可能反映了不同物种所面临的独特的氧和/或铜环境的进化反应。
Copper, zinc superoxide dismutase (SOD1) in mammals is activated principally via a copper chaperone (CCS) and to a lesser degree by a CCS-independent pathway of unknown nature. In this study, we have characterized the requirement for CCS in activating SOD1 from Drosophila. A CCS-null mutant (Ccs(n29E)) of Drosophila was created and found to phenotypically resemble Drosophila SOD1-null mutants in terms of reduced adult life span, hypersensitivity to oxidative stress, and loss of cytosolic aconitase activity. However, the phenotypes of CCS-null flies were less severe, consistent with some CCS-independent activation of Drosophila SOD1 (dSOD1). Yet SOD1 activity was not detectable in Ccsn29E flies, due largely to a striking loss of SOD1 protein. In contrast, human SOD1 expressed in CCS-null flies is robustly active and rescues the deficits in adult life span and sensitivity to oxidative stress. The dependence of dSOD1 on CCS was also observed in a yeast expression system where the dSOD1 polypeptide exhibited unusual instability in CCS-null (ccs1 Delta) yeast. The residual dSOD1 polypeptide in ccs1 Delta yeast was nevertheless active, consistent with CCS-independent activation. Stability of dSOD1 in ccs1 Delta cells was readily restored by expression of either yeast or Drosophila CCS, and this required copper insertion into the enzyme. The yeast expression system also revealed some species specificity for CCS. Yeast SOD1 exhibits preference for yeast CCS over Drosophila CCS, whereas dSOD1 is fully activated with either CCS molecule. Such variation in mechanisms of copper activation of SOD1 could reflect evolutionary responses to unique oxygen and/or copper environments faced by divergent species.