Degradation of basement membranes by Pseudomonas aeruginosa elastase

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 M(r)s in the range of 15,000 to >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 α3(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 (NC1) domain of α3(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.