Project description:The Target Of Rapamycin (TOR) protein is a Ser/Thr kinase that functions in two distinct multiprotein complexes: TORC1 and TORC2. These conserved complexes regulate many different aspects of cell growth in response to intra- and extracellular cues. Here we report the first bona fide substrate of yeast TORC1: the AGC-kinase Sch9. Six amino acids in the c-terminus of Sch9 are directly phosphorylated by TORC1. Phosphorylation of these residues is lost upon rapamycin-treatment as well as carbon- or nitrogen-starvation and transiently reduced following application of osmotic, oxidative or thermal stress. TORC1-dependent phosphorylation is required for Sch9 activity and replacement of residues phosphorylated by TORC1 with Asp/Glu renders Sch9 activity TORC1-independent. Sch9 is required for TORC1 to properly regulate ribosome biogenesis, translation initiation and entry into G0 phase, but not expression of Gln3-dependent genes. Our results suggest that Sch9 functions analogously to the mammalian TORC1 substrate S6K1 rather than the mTORC2 substrate PKB/Akt. Keywords: time course, cell type.
Project description:The Target Of Rapamycin (TOR) protein is a Ser/Thr kinase that functions in two distinct multiprotein complexes: TORC1 and TORC2. These conserved complexes regulate many different aspects of cell growth in response to intra- and extracellular cues. Here we report the first bona fide substrate of yeast TORC1: the AGC-kinase Sch9. Six amino acids in the c-terminus of Sch9 are directly phosphorylated by TORC1. Phosphorylation of these residues is lost upon rapamycin-treatment as well as carbon- or nitrogen-starvation and transiently reduced following application of osmotic, oxidative or thermal stress. TORC1-dependent phosphorylation is required for Sch9 activity and replacement of residues phosphorylated by TORC1 with Asp/Glu renders Sch9 activity TORC1-independent. Sch9 is required for TORC1 to properly regulate ribosome biogenesis, translation initiation and entry into G0 phase, but not expression of Gln3-dependent genes. Our results suggest that Sch9 functions analogously to the mammalian TORC1 substrate S6K1 rather than the mTORC2 substrate PKB/Akt. Keywords: time course, cell type. Global transcriptional analysis of rapamycin response was conducted on cells expressing either a wild-type, Sch9(WT), or TOR-independent allele of Sch9, Sch9(2D3E). Reference samples used were cells collected immediately prior to rapamycin treatment for the respective cell genotypes. Test samples were collected 20, 30, 60, 90, 120, and 180min post rapamycin treatment.
Project description:Snf1 and TORC1 are two global regulators that sense the nutrient availability and regulate the cell growth in yeast Saccharomyces cerevisiae. Here we undertook a systems biology approach to study the effect of deletion of these genes and investigate the interaction between Snf1 and TORC1 in regulation of gene expression and cell metabolism.
Project description:Snf1 and TORC1 are two global regulators that sense the nutrient availability and regulate the cell growth in yeast Saccharomyces cerevisiae. Here we undertook a systems biology approach to study the effect of deletion of these genes and investigate the interaction between Snf1 and TORC1 in regulation of gene expression and cell metabolism. 3 mutant strains (snf1?, tor1?, snf1?tor1?) together with 1 reference strain grown under both glucose-limited or amonia-limited defined media with three biological replicates for each strain
Project description:TOR kinase complex I (TORC1) is a key regulator of cell growth and metabolism in all eukaryotes. Previous studies in yeast have shown that three GTPases, Gtr1, Gtr2 and Rho1, bind TORC1 in nitrogen and amino acid starvation conditions to block phosphorylation of the S6 kinase Sch9 and activate protein phosphatase 2A (PP2A). This leads to down-regulation of 450 Sch9-dependent protein and ribosome synthesis genes, and up-regulation of 100 PP2A-dependent nitrogen assimilation and amino acid synthesis genes. Here, using bandshift assays and microarray measurements, we show that the TORC1 pathway also populates three other stress/starvation states. First, in glucose starvation conditions, the AMP activated protein kinase (AMPK/Snf1) and at least one other factor, push the TORC1 pathway into an off state where Sch9- branch signaling and PP2A-branch signaling are both inhibited. Remarkably, the TORC1 pathway remains in the glucose starvation (PP2A off) state even when cells are simultaneously starved for nitrogen and glucose. Second, in osmotic stress, the MAPK Hog1/p38 drives the TORC1 pathway into a different Sch9 off, PP2A off state, where PP2A-branch signaling can still be activated by nitrogen starvation. Third, in oxidative stress and heat stress, TORC1-Sch9 signaling is blocked while weak PP2A-branch signaling occurs. Together, our data show that the TORC1 pathway acts an information-processing hub, activating different genes in different conditions to ensure that available energy is allocated to drive growth, amino acid synthesis or a stress response, depending on the needs of the cell.
Project description:Saccharomyces cerevisiae is an excellent microorganism for industrial succinic acid production, but high succinic acid concentration will inhibit the growth of Saccharomyces cerevisiae then reduce the production of succinic acid. Through analysis the transcriptomic data of Saccharomyces cerevisiae with different genetic backgrounds under different succinic acid stress, we hope to find the response mechanism of Saccharomyces cerevisiae to succinic acid.
Project description:TORC1 is a structurally and functionally conserved multiprotein complex that regulates many aspects of eukaryote growth including the synthesis and assembly of ribosomes. The protein kinase activity of this complex is responsive to environmental cues and is potently inhibited by the natural product macrolide rapamycin. Insights into how TORC1 regulates growth have been provided with the recent identification of the rapamycin-sensitive phosphoproteome in yeast. Building on these data, we show here that Sch9, an AGC family kinase and direct substrate of TORC1, promotes ribosome biogenesis (ribi) and ribosomal protein (RP) gene expression via direct inhibitory phosphorylation of three transcription repressors, Stb3, Dot6 and Tod6. Dephosphorylation of these factors allows them to recruit the RPD3L histone deactelyase complex to ribi/RP gene promoters. Since rRNA and tRNA transcription are also under its control, Sch9 appears to be well positioned to coordinately regulate transcriptional aspects of ribosome biogenesis. ChIP-Seq of 8 S. cerevisiae strains treated with 1NM-PP1, a small molecule inhibitor for analog-sensitive kinases such as sch9-as.
Project description:A six array study using total gDNA recovered from two separate cultures of each of three different strains of Saccharomyces cerevisiae (YB-210 or CRB, Y389 or MUSH, and Y2209 or LEP) and two separate cultures of Saccharomyces cerevisiae DBY8268. Each array measures the hybridization of probes tiled across the Saccharomyces cerevisiae genome.