Analysis of Saccharomyces cerevisiae proteins induced by peroxide and superoxide stress.

Exponentially growing Saccharomyces cerevisiae cells are more sensitive to oxidants such as hydrogen peroxide and superoxides than stationary phase cells. Using disruption mutations in the genes encoding the two S. cerevisiae superoxide dismutases, we show that the principal mechanism of toxicity of redox-cycling compounds, such as menadione and plumbagin, is via the production of superoxide anions. Using two-dimensional polyacrylamide gel electrophoresis we have compared the pattern of protein expression in cells labelled with L-[35S]methionine and stressed with either H2O2 or menadione. Three groups of proteins were evident: those whose levels are elevated by both H2O2 and menadione, and those specifically induced by either H2O2 or menadione. Experiments with promoter fusions demonstrated that one of the heat inducible forms of HSP70 (SSA1) was inducible with H2O2. Furthermore, induction of the yeast H2O2-responsive TRX2 promoter by menadione required the metabolism of menadione.