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.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Nyckelord

Nitric oxide

Urinary tract infection

Flavohemoglobin

Uropathogenic Escherichia coli

Nitrosative stress

MEDICINE

MEDICIN

Biomedicin

Biomedicine

Biomedical Sciences

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