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GTPase Rheb的同源GTPase激活蛋白（GAP），是雷帕霉素复合物1（mTORC1）的机械靶标的关键调节剂。该复合物的TSC1和TSC2亚基中的突变会导致结节性硬化复合物（TSC）。我们提出了TSC2的催化天冬酰胺-拇指GAP域的晶体结构。TSC2-Rheb复合物的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，而以前建议用作催化残基的Rheb Arg15和Asp65有助于TSC2-Rheb界面并间接辅助催化。TSC2 GAP域通过与其他TSC2域的相互作用进一步稳定。我们表征了TSC2变体，这些变体部分影响TSC2的功能，并且与患者的非典型症状相关，TSC1和TSC2可能易患神经系统疾病和血管疾病，但不符合TSC的临床标准。