Effects of glucose sensing/signaling on oxidative stress response in glucose repression mutants of Schizosaccharomyces pombe.

The resistant to glucose repression mutants of Schizosaccharomyces pombe (ird5, ird13, and ird14) have a high tolerance to oxidative stress induced by H2O2. In all ird mutants, the increased expression level of the fbp1 gene can be interpreted as a lack of glucose repression in these mutants. To investigate the mechanisms of the oxidative stress response in ird mutants, we analyzed the transcription of stress response-related genes, sod1, ctt1, atf1, pap1, and sty1, under stressed and non-stressed conditions. We then analyzed the phosphorylation state of the Sty1-MAP kinase in ird mutants. Our findings support the concept of an adaptive response to oxidative stress in these mutants. In addition, these results imply that either glucose signaling mechanisms leading to glucose repression and glucose utilization as an energy source are regulated apart from each other or, like Saccharomyces cerevisiae, S. pombe might have additional glucose detection systems.