Multiprobe RNase protection assay analysis of mRNA levels for the Escherichia coli oxidative DNA glycosylase genes under conditions of oxidative stress

Escherichia call formamidopyrimidine DNA glycosylase (Fpg), MutY DNA glycos ylase, endonuclease WI, and endonuclease III are oxidative base excision re pair DNA. glycosylases that remove oxidized bases from DNA, or an incorrect base paired with an oxidized base in the case of MutY. Since genes encodin g other base excision repair proteins have been showm to be part of adaptiv e responses in E. coli, we canted to determine whether the oxidative DNA gl ycosylase genes are induced in response to conditions that cause the type o f damage their encoded proteins remove. The genes fpg, mutY, nei, and nth e ncode Fpg, MutY, endonuclease VIII, and endonuclease III, respectively, Mul tiprobe RNase protection assays were used to examine the transcript levels of these genes under conditions that induce the SoxRS, OxyR, and SOS regulo ns after a shift from anaerobic to aerobic growth and at different stages a long the growth curve. Transcript levels for all four genes decreased as ce lls progressed from log-phase growth to stationary phase and increased afte r cells were shifted from anaerobic to aerobic growth, None of the genes we re induced by hydrogen peroxide, paraquat, X rays, or conditions that induc e the SOS response.