Rapamycin-modulated transcription defines the subset of nutrient-sensitive signaling pathways directly controlled by the Tor proteins.
The immunosuppressant rapamycin inhibits Tor1p and Tor2p (target of rapamycin proteins), ultimately resulting in cellular responses characteristic of nutrient deprivation through a mechanism involving translational arrest. We measured the immediate transcriptional response of yeast grown in rich media and treated with rapamycin to investigate the direct effects of Tor proteins on nutrient-sensitive signaling pathways. The results suggest that Tor proteins directly modulate the glucose activation and nitrogen discrimination pathways and the pathways that respond to the diauxic shift (including glycolysis and the citric acid cycle). Tor proteins do not directly modulate the general amino acid control, nitrogen starvation, or sporulation (in diploid cells) pathways. Poor nitrogen quality activates the nitrogen discrimination pathway, which is controlled by the complex of the transcriptional repressor Ure2p and activator Gln3p. Inhibiting Tor proteins with rapamycin increases the electrophoretic mobility of Ure2p. The work presented here illustrates the coordinated use of genome-based and biochemical approaches to delineate a cellular pathway modulated by the protein target of a small molecule.
Hardwick
J S
JS
Howard Hughes Medical Institute, Harvard Center for Genomics Research, Department of Chemistry, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
Kuruvilla
F G
FG
Tong
J K
JK
Shamji
A F
AF
Schreiber
S L
SL
D018797:Cell Cycle Proteins; D002952:Citric Acid Cycle / Q000502:physiology; D003470:Culture Media; D005656:Fungal Proteins / Q000378:metabolism*; D020869:Gene Expression Profiling; D005947:Glucose / Q000378:metabolism; D005979:Glutathione Peroxidase; D006019:Glycolysis / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011328:Prions; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*
D018797:Cell Cycle Proteins; D003470:Culture Media; D005656:Fungal Proteins; D005947:Glucose; D005979:Glutathione Peroxidase; D009584:Nitrogen; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011328:Prions; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D020123:Sirolimus; C067020:URE2 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae; C081135:TOR2 protein, S cerevisiae