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Proteus mirabilis strains of diverse type have IgA protease activity
B W Senior1, M Albrechtsen, M A Kerr
1Department of Medical Microbiology, Dundee University Medical School, Ninewells Hospital.
Abstract:
A strain of Proteus mirabilis associated with chronic urinary tract infection was found to produce an EDTA-sensitive IgA protease that cleaved the IgA heavy chain into two fragments at sites different from those attacked by other microbial IgA1 proteases. Another 14 P. mirabilis strains of diverse type and from various clinical conditions also produced a similar IgA protease. This enzyme may be a virulence determinant of P. mirabilis.
Insights
Proteus mirabilis, a cause of chronic urinary tract infections, produces a unique EDTA-sensitive IgA protease. This enzyme cleaves the IgA heavy chain, potentially acting as a key virulence factor in P. mirabilis infections.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Chronic urinary tract infections (UTIs) are often associated with specific bacterial pathogens.
- Immunoglobulin A (IgA) is a crucial antibody in mucosal immunity, particularly in preventing UTIs.
- Bacterial proteases targeting IgA can be significant virulence factors.
Purpose of the Study:
- To investigate the enzymatic activity of IgA protease produced by Proteus mirabilis strains.
- To characterize the cleavage sites of the P. mirabilis IgA protease on the IgA heavy chain.
- To assess the potential role of this enzyme as a virulence determinant in P. mirabilis.
Main Methods:
- Isolation and characterization of IgA protease from a P. mirabilis strain linked to chronic UTIs.
- Enzymatic assays to determine the protease's sensitivity to EDTA.
- Analysis of IgA heavy chain cleavage products using protein fragmentation techniques.
Main Results:
- A novel EDTA-sensitive IgA protease was identified in P. mirabilis.
- This protease cleaved the IgA heavy chain into two distinct fragments.
- Cleavage occurred at unique sites not targeted by previously identified microbial IgA1 proteases.
- Similar IgA protease activity was detected in 14 additional P. mirabilis strains from diverse sources.
Conclusions:
- Proteus mirabilis produces a unique IgA protease capable of cleaving the IgA heavy chain at novel sites.
- The EDTA-sensitive IgA protease is conserved among various P. mirabilis strains.
- This enzyme represents a potential virulence factor contributing to the pathogenesis of P. mirabilis infections, particularly chronic UTIs.