Prooxidants prevent yeast cell death induced by genotoxic stress

It was shown earlier that DNA damage induced by alkylating agent MMS (methyl methanesulfonate) results in formation of ROS ( reactive oxygen species) in yeast cells. Here, we asked whether this ROS generation is favourable for the cells. It appeared that prooxidants rather than antioxidants stimulate the survival after MMS treatment. We found that positively charged detergents increase the survival via induction of H2O2 formation in the cells. Interestingly, prooxidants protected yeast cells from the moderate doses of MMS and enhanced the toxicity of relatively high ones. Prooxidants also protect the cells;arrested in mitosis (nocodazole treatment), indicating that the protection is mostly due to ROS-mediated transcriptional stress-response rather than due to enrichment of cell culture with highly MMS-resistant G(2)/M cells. The comparison of the published expression profile responses to prooxidant and MMS treatments identifies a set of ROS-activated genes, which are likely to protect cells from the genotoxic stress.