Ubiquitin C-terminal hydrolases cleave isopeptide- and peptide-linked ubiquitin from structured proteins but do not edit ubiquitin homopolymers.
Ubiquitin C-terminal hydrolases cleave isopeptide- and peptide-linked ubiquitin from structured proteins but do not edit ubiquitin homopolymers.
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DOI：
10.1042/bj20141349
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发表时间：
2015-03-15
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影响因子：
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通讯作者：
Hay RT
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文献类型：
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作者：
Bett JS;Ritorto MS;Ewan R;Jaffray EG;Virdee S;Chin JW;Knebel A;Kurz T;Trost M;Tatham MH;Hay RT
泛素（Ub）修饰蛋白质通过多种拓扑学上不同的Ub连接发生，包括Ube 2 W介导的N-末端α胺的单泛素化以产生肽连接的线性单Ub融合。蛋白质泛素化可以通过去泛素化酶（DUBs）的作用来逆转，其中许多酶对特定的Ub连接类型表现出惊人的偏好。在这里，我们筛选DUBs优先切割N-末端Ub从蛋白质底物，但不作用于Ub均聚物。我们发现，Ub C-末端水解酶（UCH）家族的DUBs的成员表现出这种偏好的N-末端去泛素化活性，因为它们能够切割N-末端Ub从SUMO 2和Ube 2 W，而不显示对任何八个Ub连接类型的活动。令人惊讶的是，当我们删除SUMO 2的非结构化N-末端时，UCH-L3从SUMO 2切割Ub的能力是UCH-L3的100倍，这表明UCH酶可以从结构化蛋白质中切割Ub。然而，UCH-L3也可以以类似的效率从SUMO 2的赖氨酸11（K11）切割化学合成的异肽连接的Ub，表明UCH DUB活性不限于肽连接的Ub。这些发现推进了我们对DUB的UCH家族的特异性的理解，DUB与癌症和神经变性密切相关，但其底物偏好仍不清楚。此外，我们的研究结果表明，逆转Ube 2 W介导的N-末端泛素化可能是UCH DUBs在体内的生理作用之一。泛素C末端水解酶（UCH）去泛素化酶（DUBs）的底物偏好性尚不清楚。在这里，我们报告，UCH家族DUBs有效地切割异肽和肽连接的泛素从基板，而不处理简单的Ub-Ub聚合物的任何连接类型。
Modification of proteins with ubiquitin (Ub) occurs through a variety of topologically distinct Ub linkages, including Ube2W-mediated monoubiquitylation of N-terminal alpha amines to generate peptide-linked linear mono-Ub fusions. Protein ubiquitylation can be reversed by the action of deubiquitylating enzymes (DUBs), many of which show striking preference for particular Ub linkage types. Here, we have screened for DUBs that preferentially cleave N-terminal Ub from protein substrates but do not act on Ub homopolymers. We show that members of the Ub C-terminal hydrolase (UCH) family of DUBs demonstrate this preference for N-terminal deubiquitylating activity as they are capable of cleaving N-terminal Ub from SUMO2 and Ube2W, while displaying no activity against any of the eight Ub linkage types. Surprisingly, this ability to cleave Ub from SUMO2 was 100 times more efficient for UCH-L3 when we deleted the unstructured N-terminus of SUMO2, demonstrating that UCH enzymes can cleave Ub from structured proteins. However, UCH-L3 could also cleave chemically synthesized isopeptide-linked Ub from lysine 11 (K11) of SUMO2 with similar efficiency, demonstrating that UCH DUB activity is not limited to peptide-linked Ub. These findings advance our understanding of the specificity of the UCH family of DUBs, which are strongly implicated in cancer and neurodegeneration but whose substrate preference has remained unclear. In addition, our findings suggest that the reversal of Ube2W-mediated N-terminal ubiquitylation may be one physiological role of UCH DUBs in vivo. The substrate preference of ubiquitin C-terminal hydrolase (UCH) deubiquitylating enzymes (DUBs) has been unclear. Here we report that UCH family DUBs efficiently cleave both isopeptide- and peptide-linked ubiquitin from substrates, without processing simple Ub–Ub polymers of any linkage type.