Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada.
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, M5G 1X5, Canada.
Sci Rep. 2019 Mar 11;9(1):4119. doi: 10.1038/s41598-019-40815-z.
USP37 is a deubiquitinase (DUB) with roles in the regulation of DNA damage repair and the cohesion of sister chromatids during mitosis. USP37 contains a unique insert of three ubiquitin interacting motifs (UIMs) within its catalytic DUB domain. We investigated the role of the three UIMs in the ability of USP37 to cleave di-ubiquitin chains. We found that the third UIM of USP37 recognizes the proximal ubiquitin moiety of K48 di-Ub to potentiate cleavage activity and posit that this mechanism of action may be generalizable to other chain types. In the case of K48-linked ubiquitin chains this potentiation stemmed largely from a dramatic increase in catalytic rate (k). We also developed and characterized three ubiquitin variant (UbV) inhibitors that selectively engage distinct binding sites in USP37. In addition to validating the deduced functional roles of the three UIMs in catalysis, the UbVs highlight a novel and effective means to selectively inhibit members of the difficult to drug DUB family.
USP37 是一种去泛素化酶（DUB），在 DNA 损伤修复和有丝分裂过程中姐妹染色单体的黏合中起作用。USP37 在其催化 DUB 结构域内包含三个独特的泛素相互作用基序（UIM）插入。我们研究了三个 UIM 在 USP37 切割二泛素链的能力中的作用。我们发现 USP37 的第三个 UIM 识别 K48 二泛素的近端泛素部分，以增强切割活性，并提出这种作用机制可能适用于其他链类型。对于 K48 连接的泛素链，这种增强主要来自催化速率（k）的显著增加。我们还开发并表征了三种泛素变体（UbV）抑制剂，它们选择性地结合 USP37 中的不同结合位点。除了验证三个 UIM 在催化中的推导功能作用外，UbV 还突出了一种新颖且有效的选择性抑制难以成药的 DUB 家族成员的方法。
