Dimers to doughnuts: Redox-sensitive oligomerization of 2-cysteine peroxiredoxins
Dimers to doughnuts: Redox-sensitive oligomerization of 2-cysteine peroxiredoxins
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DOI：
10.1021/bi012173m
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发表时间：
2002-04-30
期刊：
影响因子：
2.9
通讯作者：
Karplus, PA
中科院分区：
文献类型：
--
作者：
Wood, ZA;Poole, LB;Karplus, PA
2-半胱氨酸过氧化物酶（Cys peroxiredoxins，Prxs）是一个庞大而多样的过氧化物酶家族，除了其抗氧化功能外，还调节细胞信号传导途径、凋亡和分化。这些酶是专性同源二聚体（α（2）），利用独特的分子间氧化还原活性二硫键中心还原过氧化物，并已知形成两种寡聚体状态：单个α（2）二聚体或甜甜圈形（α（2））（5）十聚体。在这里，我们的特点是寡聚化特性和晶体结构的细菌2-半胱氨酸蛋白酶，鼠伤寒沙门氏菌AhpC。分析超浓聚和动态光散射表明，AhpC的低聚状态是氧化还原连接的，氧化有利于二聚状态。2.5埃分辨率的晶体结构（R = 18.5%，无R = 23.9%）的氧化，十聚体AhpC揭示了一个亚稳态的寡聚化中间体，使我们能够确定一个环，采用不同的构象与十聚体和二聚体状态，与二硫键形成有利于后者。该分子开关含有过氧化物半胱氨酸，并用于支持还原的十聚体酶中的寡聚化界面。一个结构详细的催化循环，将这些想法和链接活动的低聚状态。最后，序列比较的基础上，我们建议，所有2-Cys Prxs的酶和信号传导活动的调节由氧化还原敏感的二聚体到十聚体过渡。
2-Cys peroxiredoxins (Prxs) are a large and diverse family of peroxidases which, in addition to their antioxidant functions, regulate cell signaling pathways, apoptosis, and differentiation. These enzymes are obligate homodimers (alpha(2)), utilizing a unique intermolecular redox-active disulfide center for the reduction of peroxides, and are known to form two oligomeric states: individual alpha(2) dimers or doughnut-shaped (alpha(2))(5) decamers. Here we characterize both the oligomerization properties and crystal structure of a bacterial 2-Cys Prx, Salmonella typhimurium AhpC. Analytical ultracentrifugation and dynamic light scattering show that AhpC's oligomeric state is redox linked, with oxidization favoring the dimeric state. The 2.5 Angstrom resolution crystal structure (R = 18.5%, R-free = 23.9%) of oxidized, decameric AhpC reveals a metastable oligomerization intermediate, allowing us to identify a loop that adopts distinct conformations associated with decameric and dimeric states, with disulfide bond formation favoring the latter. This molecular switch contains the peroxidatic cysteine and acts to buttress the oligomerization interface in the reduced, decameric enzyme. A structurally detailed catalytic cycle incorporating these ideas and linking activity to oligomeric state is presented. Finally, on the basis of sequence comparisons, we suggest that the enzymatic and signaling activities of all 2-Cys Prxs are regulated by a redox-sensitive dimer to decamer transition.