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TOR and RAS pathways regulate desiccation tolerance in Saccharomyces cerevisiae
Aaron Z Welch1, Patrick A Gibney, David Botstein
1Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
Molecular Biology of the Cell
|November 23, 2012
Summary
Yeast cells can be induced to tolerate drying. Heat shock significantly boosts this desiccation tolerance by impacting cell growth and ribosome production pathways.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Desiccation tolerance in Saccharomyces cerevisiae is inducible, with stationary phase cells exhibiting higher survival rates than exponentially growing cells.
- Understanding the molecular mechanisms underlying desiccation tolerance is crucial for yeast applications and fundamental cell biology.
Purpose of the Study:
- To investigate the stresses imposed by desiccation and identify the associated stress response pathways in Saccharomyces cerevisiae.
- To elucidate the regulatory mechanisms controlling desiccation tolerance, focusing on the roles of growth rate, nutrient limitation, and specific signaling pathways.
Main Methods:
- Utilizing Saccharomyces cerevisiae cultures under various nutrient-limited continuous culture conditions.
- Inducing stress responses through transient heat shock and other stresses (hyper-ionic, reductive, oxidative, osmotic).
- Analyzing the impact of the TOR and Ras-cAMP pathways, transcription factors (Gis1p, Msn2p, Msn4p, Sfp1p), and ribosome biogenesis mutants on desiccation tolerance.
Main Results:
- Desiccation tolerance is cell-autonomous and inversely correlated with growth rate.
- Transient heat shock dramatically increases desiccation tolerance (5000-fold), more so than other tested stresses.
- The Sch9p-regulated pathway inhibits tolerance by modulating transcription factors; defects in 60S ribosome biogenesis enhance tolerance independently of growth rate.
Conclusions:
- Reduction in a specific 60S ribosome biogenesis intermediate, triggered by conditions like heat shock or nutrient deprivation, enhances yeast desiccation tolerance.
- The findings reveal a novel link between ribosome biogenesis and stress tolerance, offering insights into yeast survival strategies.
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