Structure of the ubiquitin hydrolase UCH-L3 complexed with a suicide substrate
Structure of the ubiquitin hydrolase UCH-L3 complexed with a suicide substrate
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DOI：
10.1074/jbc.m410770200
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发表时间：
2005-01-14
影响因子：
4.8
通讯作者：
Gaudet, R
中科院分区：
文献类型：
--
作者：
Misaghi, S;Galardy, PJ;Gaudet, R
泛素C末端水解酶（UCH）是一类功能不确定的泛素特异性蛋白酶。虽然没有细胞底物已被确定为UCH，其高度组织特异性的表达模式和UCH-L1突变与人类疾病的关联强烈建议的关键作用。酵母UCH Yuh 1-泛素醛复合物的结构确定了预测限制合适底物大小的活性位点交换环。我们报告了1.45分辨率的晶体结构的人UCH-L3复合物与抑制剂泛素乙烯基甲酯，抑制剂，形成一个共价加合物的活性位点半胱氨酸的泛素特异性蛋白酶。这种结构证实了抑制剂的预测机制，并允许在自由和配体结合状态下的UCH家族酶的直接比较。我们还显示了有效的水解由人UCH-L3的13个残基的肽在异肽连接与泛素，一致的UCH底物大小相当大的灵活性。我们提出了一个模型的UCH家族成员的催化循环，占较大的泛素结合物的水解。
Ubiquitin C-terminal hydrolases (UCHs) comprise a family of small ubiquitin-specific proteases of uncertain function. Although no cellular substrates have been identified for UCHs, their highly tissue-specific expression patterns and the association of UCH-L1 mutations with human disease strongly suggest a critical role. The structure of the yeast UCH Yuh1-ubiquitin aldehyde complex identified an active site crossover loop predicted to limit the size of suitable substrates. We report the 1.45 resolution crystal structure of human UCH-L3 in complex with the inhibitor ubiquitin vinylmethylester, an inhibitor that forms a covalent adduct with the active site cysteine of ubiquitin-specific proteases. This structure confirms the predicted mechanism of the inhibitor and allows the direct comparison of a UCH family enzyme in the free and ligand-bound state. We also show the efficient hydrolysis by human UCH-L3 of a 13-residue peptide in isopeptide linkage with ubiquitin, consistent with considerable flexibility in UCH substrate size. We propose a model for the catalytic cycle of UCH family members which accounts for the hydrolysis of larger ubiquitin conjugates.