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Abstract
MutY is an adenine glycosylase that has the ability to remove adenines from adenine/7,8-dihydro-8-oxoguanine (8-oxo-G) or adenine/guanine mismatches, and plays an important role in oxidative DNA damage repair. The gastric pathogen Helicobacter pylori has a homolog of the MutY enzyme. To investigate the physiological roles of MutY in H. pylori, I characterized a mutY mutant and also purified the H. pylori MutY enzyme. The mutant has an elevated spontaneous mutation frequency when incubated at 5% O2. This effect can be amplified by exposure to atmospheric oxygen levels. Most of the mutations sequenced are GC to TA transversions. Pure H. pylori MutY has the ability to remove adenines from A/8-oxo-G mismatches, but strikingly no ability to cleave A/G mismatches. The H. pylori mutY gene was able to complement an E. coli mutY mutant. H. pylori mutY mutants are only 30% as efficient as wild-type in colonizing the stomachs of mice.