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- Title
Identification of MrpI as the sole recombinase that regulates the phase variation of MR/P fimbria, a bladder colonization factor of uropathogenic Proteus mirabilis.
- Authors
Li, Xin; Lockatell, C Virginia; Johnson, David E; Mobley, Harry L T
- Abstract
Proteus mirabilis is a common cause of urinary tract infection (UTI) in individuals with structural abnormalities or long-term catheterization. The expression of mannose-resistant/Proteus-like (MR/P) fimbria is phase variable because of the inversion of a 251 bp DNA fragment that carries the promoter for the mrp operon. Previous studies have shown that mrpI, which is transcribed divergently from the mrp operon, encodes a recombinase capable of switching the orientation of this invertible element. In this study, we constructed isogenic mrpI null mutants from a clinical isolate of P. mirabilis, HI4320. A polymerase chain reaction (PCR)-based invertible element assay revealed that the isogenic mrpI null mutants were locked in one phase, either expressing (locked on) MR/P fimbriae or not (locked off), which indicated that MrpI was the sole recombinase that regulated the phase variation of MR/P fimbria. The locked-on and locked-off mutants were evaluated for virulence in the CBA mouse model of ascending UTI by co-challenges with each other and with the wild-type strain. Results from these experiments demonstrated conclusively that the MR/P fimbria was a critical bladder colonization factor of uropathogenic P. mirabilis and also suggested that the ability to switch off the expression of MR/P fimbria might be important for kidney colonization.
- Publication
Molecular microbiology, 2002, Vol 45, Issue 3, p865
- ISSN
0950-382X
- Publication type
Journal Article
- DOI
10.1046/j.1365-2958.2002.03067.x