title: Phosphorylation of the amino-terminus of the AGC kinase Gad8 prevents its interaction with TORC2.
abstract: Cell proliferation, metabolism, migration and survival are coordinated through the tight control of two target of rapamycin (TOR) kinase complexes: TORC1 and TORC2. Here, we show that a novel phosphorylation of fission yeast Gad8 (AGC kinase) on the evolutionarily conserved threonine 6 (Thr6) prevents the physical association between Gad8 and TORC2. Accordingly, this block to protein interactions by Gad8 Thr6 phosphorylation decreases TORC2-controlled activation of Gad8. Likewise, phosphorylation of Gad8 Thr6, possibly by PKC, prevents the association of Gad8 with TORC2 thereby increasing TORC2 activity, because it reduces Gad8-mediated feedback inhibition of TORC2. Consistently, the introduction of a Gad8 T6D mutant, that mimics phosphorylation, increased TORC2 activity. Increased PKC(Pck2) expression prevented Gad8-TORC2 binding and so reduced the TORC2-mediated phosphorylation of Gad8 serine 546 that activates Gad8. Interestingly, independent of the Ser546 phosphorylation status, Gad8 Thr6 phosphorylation is important for remodelling the actin cytoskeleton and survival upon potassium ion and heat stresses. In contrast, Ser546 phosphorylation is required for the control of G1 arrest, mating, cell length at division and vascular size. Finally, these findings reveal a novel mode of TORC2 activation that is essential for cell survival following stress.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
authors.forename: Gabriella M
authors.initials: GM
authors.lastname: Forte
authors.affiliation: Biological Mass Spectrometry, Cancer Research UK Manchester Institute, The Paterson Building, Wilmslow Road, Manchester M20 4BX, UK.
authors.forename: Duncan
authors.initials: D
authors.lastname: Smith
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, South Australia 5000, Australia janni.petersen@flinders.edu.au.
authors.forename: Janni
authors.initials: J
authors.lastname: Petersen
mesh_terms: D000199:Actins / Q000378:metabolism; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D011485:Protein Binding; D060066:Protein Interaction Maps; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000378:metabolism*; D013312:Stress, Physiological; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D013912:Threonine / Q000737:chemistry / Q000378:metabolism
chemical_list: D000199:Actins; D046912:Multiprotein Complexes; D029702:Schizosaccharomyces pombe Proteins; D013912:Threonine; C476401:Gad8 protein, S pombe; D000076225:Mechanistic Target of Rapamycin Complex 2; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases; D011493:Protein Kinase C; D011188:Potassium
keywords: Gad8; PKC; SGK1; Schizosaccharomyces pombe; TORC2