Development of Tester Strains Deficient in Nth/Nei DNA Glycosylases to Selectively Detect the Mutagenicity of Oxidized DNA Pyrimidines

摘要: Oxidative DNA damage is a major cause of mutation and cell death in aerobic organisms. In addition to 8-hydroxyguanine, oxidized pyrimidines play important roles mutagenesis. Salmonella typhimurium TA1535, widely used mutagenicity assays, carries hisG46 missense efficiently detects mutations at G:C base pairs. To detect oxidative mutagens that selectively modify pyrimidines, we constructed derivative strain termed YG3206, which lacks the Nei Nth glycosylases excise from DNA. This novel easily detected L-cysteine, L-penicillamine, dopamine-HCl, phenazine methosulfate, are non-mutagenic or only weakly mutagenic TA1535 parent strain. A second equivalent YG3206 but harbors plasmid pKM101 mucAB encoding polymerase R1, YG3216, was significantly sensitive ethosulfate. The compound not either Fapy-glycosylase-defective YG3001. Potassium bromate methylene blue plus visible light with metabolic activation induced YG3001 YG3216. number spontaneous His+ revertants per plate 82 ± 16 (YG3206, ΔnthΔnei), 19 4 (YG3001, Δfpg), 6 2 (TA1535), suggesting significant contribution mutagenesis by endogenous pyrimidine oxidation. absence exogenous chemical treatment, exposure fluorescent enhanced frequency approximately two-fold (YG3206), 13-fold (YG3001), 10-fold (TA1535). These results suggest certain environmental chemicals may introduce these changes can be monitored use YG3206.