Role of flavohemoglobin in combating nitrosative stress in uropathogenic Escherichia coli--implications for urinary tract infection.
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.
Svensson
Lovisa
L
School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
Poljakovic
Mirjana
M
Säve
Susanne
S
Gilberthorpe
Nicola
N
Schön
Thomas
T
Strid
Sigge
S
Corker
Hazel
H
Poole
Robert K
RK
Persson
Katarina
K
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*
D029968:Escherichia coli Proteins; D006420:Hemeproteins; D009569:Nitric Oxide; D004093:Dihydropteridine Reductase; C076538:hmp protein, E coli; D009247:NADH, NADPH Oxidoreductases