title: Role of flavohemoglobin in combating nitrosative stress in uropathogenic Escherichia coli--implications for urinary tract infection.
abstract: During the course of urinary tract infection (UTI) nitric oxide (NO) is generated as part of the host response. This study investigates the significance of the NO-detoxifying enzyme flavohemoglobin (Hmp) in protection of uropathogenic Escherichia coli (UPEC) against nitrosative stress. An hmp (J96Deltahmp) knockout mutant of UPEC strain J96 was constructed using single-gene deletion. The viability of J96Deltahmp was significantly reduced (P<0.001) compared to the wild-type strain after exposure to the NO-donor DETA/NO. The NO consumption in J96Deltahmp was significantly (P<0.001) impaired compared to J96wt. Screening UPEC isolates from patients with UTI revealed increased hmp expression in all patients. In a competition-based mouse model of UTI, the hmp mutant strain was significantly (P<0.05) out-competed by the wild-type strain. This study demonstrates, for the first time, that Hmp contributes to the protection of UPEC against NO-mediated toxicity in vitro. In addition, hmp gene expression occurs in UPEC isolates from the infected human urinary tract and UPEC that were hmp-deficient had a reduced ability to colonize the mouse urinary tract. Taken together the results suggest that NO detoxification by Hmp may be a fitness advantage factor in UPEC, and a potentially interesting target for development of novel treatment concepts for UTI.
authors.affiliation: School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Lovisa
authors.initials: L
authors.lastname: Svensson
authors.forename: Mirjana
authors.initials: M
authors.lastname: Poljakovic
authors.forename: Susanne
authors.initials: S
authors.lastname: Säve
authors.forename: Nicola
authors.initials: N
authors.lastname: Gilberthorpe
authors.forename: Thomas
authors.initials: T
authors.lastname: Schön
authors.forename: Sigge
authors.initials: S
authors.lastname: Strid
authors.forename: Hazel
authors.initials: H
authors.lastname: Corker
authors.forename: Robert K
authors.initials: RK
authors.lastname: Poole
authors.forename: Katarina
authors.initials: K
authors.lastname: Persson
mesh_terms: D000328:Adult; D000818:Animals; D015169:Colony Count, Microbial; D004093:Dihydropteridine Reductase / Q000235:genetics / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D017353:Gene Deletion; D020869:Gene Expression Profiling; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D050296:Microbial Viability / Q000187:drug effects; D008875:Middle Aged; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism* / Q000633:toxicity*; D013312:Stress, Physiological; D014552:Urinary Tract Infections / Q000382:microbiology*; D056689:Uropathogenic Escherichia coli / Q000502:physiology*
chemical_list: D029968:Escherichia coli Proteins; D006420:Hemeproteins; D009569:Nitric Oxide; D004093:Dihydropteridine Reductase; C076538:hmp protein, E coli; D009247:NADH, NADPH Oxidoreductases