title: TORC1 and TORC2 work together to regulate ribosomal protein S6 phosphorylation in Saccharomyces cerevisiae.
abstract: Nutrient-sensitive phosphorylation of the S6 protein of the 40S subunit of the eukaryote ribosome is highly conserved. However, despite four decades of research, the functional consequences of this modification remain unknown. Revisiting this enigma in Saccharomyces cerevisiae, we found that the regulation of Rps6 phosphorylation on Ser-232 and Ser-233 is mediated by both TOR complex 1 (TORC1) and TORC2. TORC1 regulates phosphorylation of both sites via the poorly characterized AGC-family kinase Ypk3 and the PP1 phosphatase Glc7, whereas TORC2 regulates phosphorylation of only the N-terminal phosphosite via Ypk1. Cells expressing a nonphosphorylatable variant of Rps6 display a reduced growth rate and a 40S biogenesis defect, but these phenotypes are not observed in cells in which Rps6 kinase activity is compromised. Furthermore, using polysome profiling and ribosome profiling, we failed to uncover a role of Rps6 phosphorylation in either global translation or translation of individual mRNAs. Taking the results together, this work depicts the signaling cascades orchestrating Rps6 phosphorylation in budding yeast, challenges the notion that Rps6 phosphorylation plays a role in translation, and demonstrates that observations made with Rps6 knock-ins must be interpreted cautiously.
authors.affiliation: Department of Molecular Biology and Institute of Genetics and Genomics of Geneva, University of Geneva, CH-1211 Geneva, Switzerland.
authors.forename: Seda
authors.initials: S
authors.lastname: Yerlikaya
authors.affiliation: Department of Molecular Biology and Institute of Genetics and Genomics of Geneva, University of Geneva, CH-1211 Geneva, Switzerland.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Meusburger
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Romika
authors.initials: R
authors.lastname: Kumari
authors.affiliation: Department of Molecular Biology and Institute of Genetics and Genomics of Geneva, University of Geneva, CH-1211 Geneva, Switzerland.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Huber
authors.affiliation: Max F. Perutz Laboratories, Department of Biochemistry, University of Vienna, A1030 Vienna, Austria.
authors.forename: Dorothea
authors.initials: D
authors.lastname: Anrather
authors.affiliation: Banting and Best Department of Medical Research, Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Costanzo
authors.affiliation: Banting and Best Department of Medical Research, Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Boone
authors.affiliation: Max F. Perutz Laboratories, Department of Biochemistry, University of Vienna, A1030 Vienna, Austria.
authors.forename: Gustav
authors.initials: G
authors.lastname: Ammerer
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.
authors.forename: Pavel V
authors.initials: PV
authors.lastname: Baranov
authors.affiliation: Department of Molecular Biology and Institute of Genetics and Genomics of Geneva, University of Geneva, CH-1211 Geneva, Switzerland Swiss National Centre for Competence in Research Programme Chemical Biology, 1211 Geneva, Switzerland robbie.loewith@unige.ch.
authors.forename: Robbie
authors.initials: R
authors.lastname: Loewith
mesh_terms: D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011132:Polyribosomes / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000235:genetics / Q000378:metabolism*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D038601:Ribosomal Protein S6; D029701:Saccharomyces cerevisiae Proteins; C561842:TORC1 protein complex, S cerevisiae; D014157:Transcription Factors; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases