Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
Department of Pharmacology, Yale University, New Haven, CT, USA.
Nat Commun. 2022 Aug 15;13(1):4788. doi: 10.1038/s41467-022-32541-4.
RhoGAP proteins are key regulators of Rho family GTPases and influence a variety of cellular processes, including cell migration, adhesion, and cytokinesis. These GTPase activating proteins (GAPs) downregulate Rho signaling by binding and enhancing the intrinsic GTPase activity of Rho proteins. Deleted in liver cancer 1 (DLC1) is a tumor suppressor and ubiquitously expressed RhoGAP protein; its activity is regulated in part by binding p120RasGAP, a GAP protein for the Ras GTPases. In this study, we report the co-crystal structure of the p120RasGAP SH3 domain bound directly to DLC1 RhoGAP, at a site partially overlapping the RhoA binding site and impinging on the catalytic arginine finger. We demonstrate biochemically that mutation of this interface relieves inhibition of RhoGAP activity by the SH3 domain. These results reveal the mechanism for inhibition of DLC1 RhoGAP activity by p120RasGAP and demonstrate the molecular basis for direct SH3 domain modulation of GAP activity.
RhoGAP 蛋白是 Rho 家族 GTP 酶的关键调节剂，影响多种细胞过程，包括细胞迁移、黏附和胞质分裂。这些 GTP 酶激活蛋白（GAPs）通过结合并增强 Rho 蛋白的内在 GTP 酶活性来下调 Rho 信号。肝癌缺失基因 1（DLC1）是一种肿瘤抑制因子和普遍表达的 RhoGAP 蛋白；其活性部分受 p120RasGAP 调节，后者是 Ras GTP 酶的 GAP 蛋白。在这项研究中，我们报告了 p120RasGAP SH3 结构域与 DLC1 RhoGAP 直接结合的共晶体结构，该结构位于与 RhoA 结合位点部分重叠且干扰催化精氨酸指的部位。我们通过生化实验证明，该界面的突变可解除 SH3 结构域对 RhoGAP 活性的抑制。这些结果揭示了 p120RasGAP 抑制 DLC1 RhoGAP 活性的机制，并证明了 SH3 结构域直接调节 GAP 活性的分子基础。
