title: Crystal structure of the Ego1-Ego2-Ego3 complex and its role in promoting Rag GTPase-dependent TORC1 signaling.
abstract: The target of rapamycin complex 1 (TORC1) integrates various hormonal and nutrient signals to regulate cell growth, proliferation, and differentiation. Amino acid-dependent activation of TORC1 is mediated via the yeast EGO complex (EGOC) consisting of Gtr1, Gtr2, Ego1, and Ego3. Here, we identify the previously uncharacterized Ycr075w-a/Ego2 protein as an additional EGOC component that is required for the integrity and localization of the heterodimeric Gtr1-Gtr2 GTPases, equivalent to mammalian Rag GTPases. We also report the crystal structure of the Ego1-Ego2-Ego3 ternary complex (EGO-TC) at 2.4 Å resolution, in which Ego2 and Ego3 form a heterodimer flanked along one side by Ego1. Structural data also reveal the structural conservation of protein components between the yeast EGO-TC and the human Ragulator, which acts as a GEF for Rag GTPases. Interestingly, however, artificial tethering of Gtr1-Gtr2 to the vacuolar membrane is sufficient to activate TORC1 in response to amino acids even in the absence of the EGO-TC. Our structural and functional data therefore support a model in which the EGO-TC acts as a scaffold for Rag GTPases in TORC1 signaling.
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Katie
authors.initials: K
authors.lastname: Powis
authors.affiliation: National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
authors.forename: Tianlong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Panchaud
authors.affiliation: National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Claudio
authors.initials: C
authors.lastname: De Virgilio
authors.affiliation: National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Ding
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020836:Protein Structure, Quaternary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C121263:GTR2 protein, S cerevisiae; C121262:Gtr1 protein, S cerevisiae; C501979:MEH1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C561842:TORC1 protein complex, S cerevisiae; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; C530964:SCH9 protein, S cerevisiae; D020559:Monomeric GTP-Binding Proteins