TOR and RAS pathways regulate desiccation tolerance in Saccharomyces cerevisiae. Author Aaron Welch, Patrick Gibney, David Botstein, Douglas Koshland Publication Year 2013 Type Journal Article Abstract Tolerance to desiccation in cultures of Saccharomyces cerevisiae is inducible; only one in a million cells from an exponential culture survive desiccation compared with one in five cells in stationary phase. Here we exploit the desiccation sensitivity of exponentially dividing cells to understand the stresses imposed by desiccation and their stress response pathways. We found that induction of desiccation tolerance is cell autonomous and that there is an inverse correlation between desiccation tolerance and growth rate in glucose-, ammonia-, or phosphate-limited continuous cultures. A transient heat shock induces a 5000-fold increase in desiccation tolerance, whereas hyper-ionic, -reductive, -oxidative, or -osmotic stress induced much less. Furthermore, we provide evidence that the Sch9p-regulated branch of the TOR and Ras-cAMP pathway inhibits desiccation tolerance by inhibiting the stress response transcription factors Gis1p, Msn2p, and Msn4p and by activating Sfp1p, a ribosome biogenesis transcription factor. Among 41 mutants defective in ribosome biogenesis, a subset defective in 60S showed a dramatic increase in desiccation tolerance independent of growth rate. We suggest that reduction of a specific intermediate in 60S biogenesis, resulting from conditions such as heat shock and nutrient deprivation, increases desiccation tolerance. Keywords Gene Knockout Techniques, Signal Transduction, Saccharomyces cerevisiae, Transcription Factors, Culture Media, Saccharomyces cerevisiae Proteins, Adaptation, Physiological, Cyclic AMP-Dependent Protein Kinases, Dehydration, Phosphatidylinositol 3-Kinases, ras Proteins, Ribosome Subunits, Large, Eukaryotic, Sirolimus, Stress, Physiological Journal Mol Biol Cell Volume 24 Issue 2 Pages 115-28 Date Published 01/2013 Alternate Journal Mol. Biol. Cell Google ScholarBibTeXEndNote X3 XML