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Degradation of basement membranes by Pseudomonas aeruginosa elastase
P A Bejarano1, J P Langeveld, B G Hudson
1Department of Biochemistry, University of Kansas Medical Center, Kansas City 66103.
Abstract:
Pseudomonas aeruginosa virulence has been attributed in part to extracellular proteinases. We found that one of these proteinases, elastase, extensively degrades intact basement membranes from bovine anterior-lens capsules, bovine glomeruli, and bovine lung, producing about 9, 14, and 9 fragments, respectively, with Mrs in the range of 15,000 to greater than 200,000, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (nonreducing conditions). Release of hydroxyproline showed that collagen IV was degraded by elastase. Degradation of the newly discovered alpha 3(IV) collagen chain was shown by immunoblotting of digests with Goodpasture's syndrome serum, which contains antibodies that react with an epitope located in the carboxyl-terminal globular (NCl) domain of alpha 3(IV). Comparison of total protein release with collagen IV release showed that noncollagenous protein components were solubilized to the same extent as collagen IV. The extensive degradation of the basement membranes described here suggests a role for elastase in the pathogenic mechanism at the local level when P. aeruginosa infection is present.
Insights
Pseudomonas aeruginosa elastase significantly degrades basement membranes, including collagen IV and its alpha 3(IV) chain. This proteinase activity contributes to bacterial virulence and tissue damage during infection.
Area of Science:
- Microbiology
- Biochemistry
- Pathology
Background:
- Pseudomonas aeruginosa extracellular proteinases contribute to virulence.
- Elastase is a key proteinase implicated in bacterial pathogenesis.
Purpose of the Study:
- To investigate the degradation of basement membranes by Pseudomonas aeruginosa elastase.
- To determine the specific components of basement membranes affected by elastase.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein fragments.
- Hydroxyproline release assay to assess collagen degradation.
- Immunoblotting with Goodpasture's syndrome serum to detect alpha 3(IV) collagen chain degradation.
Main Results:
- Elastase extensively degraded intact basement membranes from bovine lens capsules, glomeruli, and lung.
- Degradation of collagen IV and the alpha 3(IV) collagen chain was confirmed.
- Noncollagenous protein components were solubilized similarly to collagen IV.
Conclusions:
- Pseudomonas aeruginosa elastase extensively degrades basement membrane components.
- Elastase likely plays a significant role in the local pathogenic mechanisms of P. aeruginosa infections.
- These findings highlight elastase as a potential therapeutic target.