Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany.
Westfälische Wilhelms-Universität, Institute of Biochemistry, Wilhelm Klemm-Str. 2, 48149 Münster, Germany; Westfälische Wilhelms-Universität, Institute of Molecular Tumor Biology, Robert-Koch-Str. 43, 48149 Münster, Germany.
Structure. 2020 Aug 4;28(8):933-942.e4. doi: 10.1016/j.str.2020.05.008. Epub 2020 Jun 4.
The TSC complex is the cognate GTPase-activating protein (GAP) for the small GTPase Rheb and a crucial regulator of the mechanistic target of rapamycin complex 1 (mTORC1). Mutations in the TSC1 and TSC2 subunits of the complex cause tuberous sclerosis complex (TSC). We present the crystal structure of the catalytic asparagine-thumb GAP domain of TSC2. A model of the TSC2-Rheb complex and molecular dynamics simulations suggest that TSC2 Asn1643 and Rheb Tyr35 are key active site residues, while Rheb Arg15 and Asp65, previously proposed as catalytic residues, contribute to the TSC2-Rheb interface and indirectly aid catalysis. The TSC2 GAP domain is further stabilized by interactions with other TSC2 domains. We characterize TSC2 variants that partially affect TSC2 functionality and are associated with atypical symptoms in patients, suggesting that mutations in TSC1 and TSC2 might predispose to neurological and vascular disorders without fulfilling the clinical criteria for TSC.
TSC 复合物是小 GTP 酶 Rheb 的同源 GTP 酶激活蛋白 (GAP)，也是机械靶标雷帕霉素复合物 1 (mTORC1) 的关键调节因子。该复合物的 TSC1 和 TSC2 亚基的突变会导致结节性硬化症 (TSC)。我们展示了 TSC2 的催化天冬酰胺-拇指 GAP 结构域的晶体结构。TSC2-Rheb 复合物模型和分子动力学模拟表明，TSC2 Asn1643 和 Rheb Tyr35 是关键的活性位点残基，而先前被提议为催化残基的 Rheb Arg15 和 Asp65 则有助于 TSC2-Rheb 界面并间接辅助催化。TSC2 GAP 结构域还通过与其他 TSC2 结构域的相互作用进一步稳定。我们对部分影响 TSC2 功能的 TSC2 变体进行了表征，这些变体与患者的非典型症状有关，这表明 TSC1 和 TSC2 的突变可能导致神经和血管疾病，而无需满足 TSC 的临床标准。
