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Transient adaptation to oxidative stress in yeast
J M Davies1, C V Lowry, K J Davies
1Department of Medicine, Albany Medical College, New York 12208.
Archives of Biochemistry and Biophysics
|February 20, 1995
Summary
Yeast cells can adapt to hydrogen peroxide (H2O2) oxidative stress through a transient adaptation process. Pretreatment with low H2O2 concentrations enhances survival and growth rates upon subsequent challenge, requiring protein synthesis.
Area of Science:
- Cellular biology
- Biochemistry
- Microbiology
Background:
- Oxidative stress, particularly from hydrogen peroxide (H2O2), poses a significant threat to cellular integrity.
- While adaptive responses are known in bacteria and some mammalian cells, detailed mechanisms in yeast require further elucidation.
- Naive Saccharomyces cerevisiae cells exhibit sensitivity to H2O2, with growth arrest upon exposure.
Purpose of the Study:
- To investigate adaptive responses to hydrogen peroxide (H2O2) oxidative stress in Saccharomyces cerevisiae.
- To determine optimal conditions for H2O2 adaptation and characterize its transient nature.
- To explore the molecular basis of H2O2 adaptation, including protein synthesis requirements.
Main Methods:
- Exposure of Saccharomyces cerevisiae strain RZ53 to varying concentrations and durations of H2O2 for pretreatment and challenge.
- Assessment of cell survival, plating efficiency, and growth rates post-H2O2 exposure.
- Investigation of adaptation reversibility (deadaptation) and dependence on protein synthesis using cycloheximide.
Main Results:
- Pretreatment with low H2O2 concentrations (e.g., 0.4 mM) significantly enhances survival (90-100%) and growth rates (15-30% faster) against a subsequent H2O2 challenge (0.8 mM).
- Optimal adaptation observed with specific cell densities, H2O2 concentrations, and pretreatment-challenge intervals.
- H2O2 adaptation is transient, reversing within 60-90 minutes of growth without H2O2, and requires protein synthesis, indicated by differential protein expression (21 increased, 8 decreased).
Conclusions:
- Saccharomyces cerevisiae exhibits a true transient adaptation to H2O2 oxidative stress, not selection of resistant subpopulations.
- This adaptation involves increased expression of genes encoding protective and repair enzymes, mediated by protein synthesis.
- The findings provide insights into cellular defense mechanisms against oxidative stress applicable across different organisms.