The effect of oxidative stress onSaccharomyces cerevisiae

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Abstract
Reactive oxygen species (ROS) are highly reactive and damage cellular constituents such as DNA, lipids and proteins. All aerobically growing organisms are exposed to ROS. As a result most organisms have evolved mechanisms to protect their components against ROS. This review describes the oxidant defence systems of the yeast Saccharomyces cerevisiae, which is an ideal eukaryotic model system to analyse the molecular events in response to oxidative stress. Yeast posses a similar range of anti-oxidant molecules and enzymes to those found in higher eukaryotes. Exponentially growing S. cerevisiae have at least two distinct adaptive stress responses to oxidants, one of which is responsive towards H2O2 and the other is induced by exposure to compounds that generate superoxide anion. The identification of a number of transcription factors (Yap1, Mac1, Ace1) which are important in the regulation of metal metabolism and homeostasis that are also involved in mediating resistance towards oxidants suggests a link between metal metabolism and oxidative stress. Heat-shock, nutrient starvation and entry into the stationary phase of growth also lead to increased resistance toward oxidants. The available evidence suggests that the mechanism by which these stresses result in oxidant resistance may be different from those utilised by exponentially growing cells.