Oxidative stress promotes specific protein damage in Saccharomyces cerevisiae

We have analyzed the proteins that are oxidatively damaged when Saccharomyces cerevisiae cells are ex- posed to stressing conditions. Carbonyl groups generated by hydrogen peroxide or menadione on proteins of aero- bically respiring cells were detected by Western blotting, purified, and identified. Mitochondrial proteins such as E2 subunits of both pyruvate dehydrogenase and ␣-keto- glutarate dehydrogenase, aconitase, heat-shock protein 60, and the cytosolic fatty acid synthase (␣ subunit) and glyceraldehyde-3-phosphate dehydrogenase were the ma- jor targets. In addition we also report the in vivo modifi- cation of lipoamide present in the above-mentioned E2 subunits under the stressing conditions tested and that this also occurs with the homologous enzymes present in Escherichia coli cells that were used for comparative analysis. Under fermentative conditions, the main pro- tein targets in S. cerevisiae cells treated with hydrogen peroxide or menadione were pyruvate decarboxylase, enolase, fatty acid synthase, and glyceraldehyde-3-phos- phate dehydrogenase. Under the stress conditions tested, fermenting cells exhibit a lower viability than aerobically respiring cells and, consistently, increased peroxide gen- eration as well as higher content of protein carbonyls and lipid peroxides. Our results strongly suggest that the oxidative stress in prokaryotic and eukaryotic cells shares common features