泛素特异性蛋白酶7的激活动力学
Activation dynamics of ubiquitin-specific protease 7.
作者信息
Valles Gabrielle J, Korchak Emilie J, Geddes-Buehre Dane H, Jaiswal Nancy, Korzhnev Dmitry M, Bezsonova Irina
机构信息
Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT 06032.
出版信息
Proc Natl Acad Sci U S A. 2025 May 27;122(21):e2426632122. doi: 10.1073/pnas.2426632122. Epub 2025 May 21.
Ubiquitin-specific protease 7 (USP7) is a deubiquitinating enzyme that plays a crucial role in cellular processes, including the maintenance of genome stability and regulation of antiviral and immune responses. Its dysfunction is linked to various cancers and neurodevelopmental disorders such as Hao-Fountain syndrome. Unlike other USP-family enzymes, the triad of catalytic residues in USP7 adopts an inactive conformation and undergoes rearrangement into the active state upon substrate binding. Despite its potential importance for regulating the enzyme's activity, the dynamics of USP7 have not been explored. In this study, we combine advanced CPMG NMR relaxation dispersion measurements with the analysis of enzyme kinetics to investigate the conformational dynamics of USP7 in solution and its role in enzyme activation. Our results suggest that apo-USP7 exists in a dynamic equilibrium, transiently switching between inactive and low-populated active conformations, indicating that enzyme activation can occur spontaneously, even in the absence of a substrate. Furthermore, we show that the Hao-Fountain syndrome-associated variant G392D enhances the conformational dynamics of the enzyme, leading to a significant increase in its catalytic activity. This study captures the sparsely populated, "invisible" active conformation of USP7 and demonstrates how changes in enzyme dynamics can contribute to activity, offering broader insights into enzyme function and disease mechanisms.
泛素特异性蛋白酶7(USP7)是一种去泛素化酶,在细胞过程中发挥关键作用,包括维持基因组稳定性以及调节抗病毒和免疫反应。其功能障碍与多种癌症和神经发育障碍有关,如郝-方丹综合征。与其他USP家族酶不同,USP7中的催化残基三联体处于无活性构象,在底物结合后会重排为活性状态。尽管其对调节酶活性具有潜在重要性,但USP7的动力学尚未得到研究。在本研究中,我们将先进的CPMG NMR弛豫色散测量与酶动力学分析相结合,以研究USP7在溶液中的构象动力学及其在酶激活中的作用。我们的结果表明,无底物的USP7以动态平衡存在,在无活性和低丰度活性构象之间瞬时切换,这表明即使在没有底物的情况下,酶激活也能自发发生。此外,我们表明与郝-方丹综合征相关的变体G392D增强了酶的构象动力学,导致其催化活性显著增加。本研究捕捉到了USP7稀少的、“不可见”的活性构象,并展示了酶动力学变化如何影响活性,为酶功能和疾病机制提供了更广泛的见解。