THE EFFECT OF OXIDATIVE STRESS ON SACCHAROMYCES-CEREVISIAE

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 descr ibes the oxidant defence systems of the yeast Saccharomyces cerevisiae , which is an ideal eukaryotic model system to analyse the molecular e vents in response to oxidative stress, Yeast posses a similar range of anti-oxidant molecules and enzymes to those found in higher eukaryote s, Exponentially growing S. cerevisiae have at least two distinct adap tive stress responses to oxidants, one of which is responsive towards H2O2 and the other is induced by exposure to compounds that generate s uperoxide anion, The identification of a number of transcription facto rs (Yap1, Mac1, Ace1) which are important in the regulation of metal m etabolism and homeostasis that are also involved in mediating resistan ce towards oxidants suggests a link between metal metabolism and oxida tive stress, Heat-shock, nutrient starvation and entry into the statio nary phase of growth also lead to increased resistance toward oxidants , The available evidence suggests that the mechanism by which these st resses result in oxidant resistance may be different from those utilis ed by exponentially growing cells.