Lon Protease Affects the RdxA Nitroreductase Activity and Metronidazole Susceptibility in Helicobacter pylori

BackgroundThe lon gene of Helicobacter pylori strains is constitutively expressed during growth. However, virtually nothing is understood concerning the role of Lon in H.pylori. This study examined the function and physiological role of Lon in H.pylori (HpLon) using a trapping approach to identify putative Lon binding partners in the bacterium. Materials and MethodsProtease-deficient Lon was expressed and served as the bait in trapping approach to capture the interacting partners in H.pylori. The antibiotic susceptibility of wild-type and lon derivative mutants was determined by the E test trips and the disc diffusion assay. The effect of HpLon on RdxA activity was detected the change in NADPH oxidation and metronidazole reduction by spectrophotometer. ResultsLon in Helicobacter pylori (HpLon) interacting partners are mostly associated with metronidazole activation. lon mutant presents more susceptible to metronidazole than that of the wild type, and this phenotype is recovered by complementation of the wild-type Lon. We found that the ATPases associated with a variety of cellular activities (AAA(+)) module of HpLon causes a decrease in both NADPH oxidase and Mtz reductase activity in RdxA, a major Mtz-activating enzyme in H.pylori. ConclusionMetronidazole resistance of H.pylori causes the serious medical problem worldwide. In this study, HpLon is involved in metronidazole susceptibility among H.pylori strains. We provide the evidence that HpLon alters RdxA activity in vitro. The decrease in metronidazole activation caused by HpLon is possibly prior to accumulate mutation in rdxA gene before the metronidazole-resistant strains to be occurred.