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Proteus mirabilis fimbriae: identification, isolation, and characterization of a new ambient-temperature fimbria
G Massad1, F K Bahrani, H L Mobley
1Department of Medicine, University of Maryland School of Medicine, Baltimore 21201.
Abstract:
Urinary tract infections involving Proteus mirabilis may lead to complications including bladder and kidney stones, acute pyelonephritis, and bacteremia. This bacterium produces a number of fimbriae, two of which, MR/P fimbria and P. mirabilis fimbria, have been shown to contribute to the ability of this pathogen to colonize the bladder and kidney. We have now purified and characterized a previously undescribed fimbria of P. mirabilis, named ambient-temperature fimbria (ATF). Electron microscopy of a pure preparation and immunogold labeling of cells demonstrated that ATF was fimbrial in nature. The major fimbrial subunit of ATF has an apparent molecular weight of 24,000. The N-terminal amino acid sequence, E-X-T-G-T-P-A-P-T-E-V-T-V-D-G-G-T-I-D-F, did not show significant similarity to that of any previously described fimbrial protein. ATF was expressed by all eight P. mirabilis strains examined. Culture conditions affected expression of ATF, with optimal expression observed in static broth cultures at 23 degrees C. This fimbria was not produced by cells grown at 42 degrees C or on solid medium. Expression of ATF did not correlate with mannose-resistant/Proteus-like (MR/P) or mannose-resistant/Klebsiella-like (MR/K) hemagglutination and represents a novel fimbria of P. mirabilis.
Insights
Researchers discovered a new bacterial appendage called ambient-temperature fimbria (ATF) in Proteus mirabilis. This novel fimbria is expressed by all strains and may play a role in urinary tract infections.
Area of Science:
- Microbiology
- Bacteriology
Background:
- Proteus mirabilis causes urinary tract infections (UTIs) with potential complications like kidney stones.
- Fimbriae, such as MR/P fimbria and P. mirabilis fimbria, are key virulence factors enabling bacterial colonization of the urinary tract.
Purpose of the Study:
- To identify and characterize novel fimbriae produced by Proteus mirabilis.
- To investigate the structural and expression characteristics of the newly discovered ambient-temperature fimbria (ATF).
Main Methods:
- Purification and characterization of the novel fimbria.
- Electron microscopy and immunogold labeling to confirm fimbrial nature.
- N-terminal amino acid sequencing of the major fimbrial subunit.
- Analysis of ATF expression under various culture conditions (temperature, static vs. solid medium).
Main Results:
- A previously undescribed fimbria, named ambient-temperature fimbria (ATF), was purified and characterized.
- Electron microscopy and immunogold labeling confirmed ATF's fimbrial structure.
- The major subunit has a molecular weight of 24,000 and a unique N-terminal sequence.
- ATF was expressed by all eight P. mirabilis strains tested.
- Optimal ATF expression occurred in static broth cultures at 23°C, with no production at 42°C or on solid media.
- ATF expression did not correlate with MR/P or MR/K hemagglutination.
Conclusions:
- Ambient-temperature fimbria (ATF) represents a novel fimbria of Proteus mirabilis.
- ATF is expressed across different strains under specific environmental conditions.
- Further research is needed to elucidate ATF's specific role in P. mirabilis pathogenesis and UTI development.