Open AccessTOR Controls Transcriptional and Translational Programs via Sap-Sit4 Protein Phosphatase Signaling Effectors
Author(s) -
John R. Rohde,
Susan G. Campbell,
Sara A. Zurita-Martinez,
N. Shane Cutler,
Mark P. Ashe,
María E. Cárdenas
Publication year - 2004
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.24.19.8332-8341.2004
Subject(s) - biology , protein phosphatase 2 , phosphatase , hyperphosphorylation , saccharomyces cerevisiae , effector , tor signaling , translation (biology) , microbiology and biotechnology , protein subunit , kinase , gene , genetics , phosphorylation , messenger rna
The Tor kinases are the targets of the immunosuppressive drug rapamycin and couple nutrient availability to cell growth. In the budding yeastSaccharomyces cerevisiae , the PP2A-related phosphatase Sit4 together with its regulatory subunit Tap42 mediates several Tor signaling events. Sit4 interacts with other potential regulatory proteins known as the Saps. Deletion of theSAP orSIT4 genes confers increased sensitivity to rapamycin and defects in expression of subsets of Tor-regulated genes. Sap155, Sap185, or Sap190 can restore these responses. Strains lacking Sap185 and Sap190 are hypersensitive to rapamycin, and this sensitivity is Gcn2 dependent and correlated with a defect in translation, constitutive eukaryotic initiation factor 2α hyperphosphorylation, induction ofGCN4 translation, and hypersensitivity to amino acid starvation. We conclude that Tor signals via Sap-Sit4 complexes to control both transcriptional and translational programs that couple cell growth to amino acid availability.