ANALYSIS OF SACCHAROMYCES-CEREVISIAE PROTEINS INDUCED BY PEROXIDE ANDSUPEROXIDE STRESS

Exponentially growing Saccharomyces cerevisiae cells are more sensitiv e to oxidants such as hydrogen peroxide and superoxides than stationar y phase cells. Using disruption mutations in the genes encoding the tw o S. cerevisiae superoxide dismutases, we show that the principal mech anism of toxicity of redox-cycling compounds, such as menadione and pl umbagin, is via the production of superoxide anions. Using two-dimensi onal polyacrylamide gel electrophoresis we have compared the pattern o f protein expression in cells labelled with L-[S-35]methionine and str essed with either H2O2 or menadione. Three groups of proteins were evi dent: those whose levels are elevated by both H2O2 and menadione, and those specifically induced by either H2O2 or menadione. Experiments wi th promoter fusions demonstrated that one of the heat inducible forms of HSP7O (SSA1) was inducible with H2O2. Furthermore, induction of the yeast H2O2-responsive TRX2 promoter by menadione required the metabol ism of menadione.