Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
Nat Commun. 2013;4:1569. doi: 10.1038/ncomms2567.
Protein ubiquitination is a highly versatile post-translational modification that regulates as diverse processes as protein degradation and kinase activation. Deubiquitinases hydrolyse ubiquitin modifications from proteins and are hence key regulators of the ubiquitin system. Ovarian tumour deubiquitinases comprise a family of fourteen human enzymes, many of which regulate cellular signalling pathways. Ovarian tumour deubiquitinases are cysteine proteases that cleave polyubiquitin chains in vitro and in cells, but little is currently known about their regulation. Here we show that ovarian tumour deubiquitinases are susceptible to reversible oxidation of the catalytic cysteine residue. High-resolution crystal structures of the catalytic domain of A20 in four different oxidation states reveal that the reversible form of A20 oxidation is a cysteine sulphenic acid intermediate, which is stabilised by the architecture of the catalytic centre. Using chemical tools to detect sulphenic acid intermediates, we show that many ovarian tumour deubiquitinases undergo reversible oxidation upon treatment with H2O2, revealing a new mechanism to regulate deubiquitinase activity.
蛋白质泛素化是一种高度灵活的翻译后修饰，调节着多种过程，如蛋白质降解和激酶激活。去泛素化酶从蛋白质上水解泛素修饰，因此是泛素系统的关键调节剂。卵巢肿瘤去泛素化酶由十四个人类酶组成，其中许多调节细胞信号通路。卵巢肿瘤去泛素化酶是半胱氨酸蛋白酶，可在体外和细胞内切割多泛素链，但目前对其调节知之甚少。在这里，我们表明卵巢肿瘤去泛素化酶易受催化半胱氨酸残基的可逆氧化。四种不同氧化态的 A20 催化结构域的高分辨率晶体结构表明，A20 氧化的可逆形式是半胱氨酸亚磺酸中间物，其被催化中心的结构稳定。使用化学工具检测亚磺酸中间物，我们表明许多卵巢肿瘤去泛素化酶在 H2O2 处理时发生可逆氧化，揭示了一种新的调节去泛素化酶活性的机制。
