6cet
Cryo-EM structure of GATOR1
Structural highlights
DiseaseNPRL2_HUMAN Inactivating mutations and truncating deletions in the genes encoding GATOR1 proteins, including NPRL2, are detected in glioblastoma and ovarian tumors and are associated with loss of heterozygosity events. Inactivation of GATOR1 proteins promotes constitutive localization of mTORC1 to the lysosomal membrane and blocks mTORC1 inactivation following amino acid withdrawal (PubMed:23723238).[1] The disease is caused by mutations affecting the gene represented in this entry. FunctionNPRL2_HUMAN As a component of the GATOR1 complex functions as an inhibitor of the amino acid-sensing branch of the TORC1 pathway. The GATOR1 complex strongly increases GTP hydrolysis by RRAGA and RRAGB within RRAGC-containing heterodimers, thereby deactivating RRAGs, releasing mTORC1 from lysosomal surface and inhibiting mTORC1 signaling. The GATOR1 complex is negatively regulated by GATOR2 the other GATOR subcomplex in this amino acid-sensing branch of the TORC1 pathway.[2] Suppresses Src-dependent tyrosine phosphorylation and activation of PDPK1 and its downstream signaling. Down-regulates PDPK1 kinase activity by interfering with tyrosine phosphorylation at 'Tyr-9', 'Tyr-373' and 'Tyr-376' residues. May act as a tumor suppressor. Suppresses cell growth and enhances sensitivity to various anticancer drugs.[3] Publication Abstract from PubMedNutrients, such as amino acids and glucose, signal through the Rag GTPases to activate mTORC1. The GATOR1 protein complex-comprising DEPDC5, NPRL2 and NPRL3-regulates the Rag GTPases as a GTPase-activating protein (GAP) for RAGA; loss of GATOR1 desensitizes mTORC1 signalling to nutrient starvation. GATOR1 components have no sequence homology to other proteins, so the function of GATOR1 at the molecular level is currently unknown. Here we used cryo-electron microscopy to solve structures of GATOR1 and GATOR1-Rag GTPases complexes. GATOR1 adopts an extended architecture with a cavity in the middle; NPRL2 links DEPDC5 and NPRL3, and DEPDC5 contacts the Rag GTPase heterodimer. Biochemical analyses reveal that our GATOR1-Rag GTPases structure is inhibitory, and that at least two binding modes must exist between the Rag GTPases and GATOR1. Direct interaction of DEPDC5 with RAGA inhibits GATOR1-mediated stimulation of GTP hydrolysis by RAGA, whereas weaker interactions between the NPRL2-NPRL3 heterodimer and RAGA execute GAP activity. These data reveal the structure of a component of the nutrient-sensing mTORC1 pathway and a non-canonical interaction between a GAP and its substrate GTPase. Architecture of the human GATOR1 and GATOR1-Rag GTPases complexes.,Shen K, Huang RK, Brignole EJ, Condon KJ, Valenstein ML, Chantranupong L, Bomaliyamu A, Choe A, Hong C, Yu Z, Sabatini DM Nature. 2018 Apr 5;556(7699):64-69. doi: 10.1038/nature26158. Epub 2018 Mar 28. PMID:29590090[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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