Lon protease affects the RdxA nitroreductase activity and metronidazole susceptibility in Helicobacter pylori.
BACKGROUND
The 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.


METHODS
Protease-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.


RESULTS
Lon 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.


CONCLUSIONS
Metronidazole 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.
Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 300, Taiwan.
I-Fan
IF
Tu
Jiahn-Haur
JH
Liao
Feng-Ling
FL
Yang
Nien-Tsung
NT
Lin
Hong-Lin
HL
Chan
Shih-Hsiung
SH
Wu
D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D009601:Nitroreductases / Q000235:genetics / Q000378:metabolism*; D049070:Protease La / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D008795:Metronidazole; D019255:NADPH Oxidases; D009601:Nitroreductases; C476646:RdxA protein, Helicobacter pylori; D049070:Protease La
Helicobacter pylori; Lon; metronidazole; protease