Degradation of Outer Membrane Protein A in Escherichia coli Killing by Neutrophil Elastase

In determining the mechanism of neutrophil elastase (NE)–mediated killing of Escherichia coli , we found that NE degraded outer membrane protein A (OmpA), localized on the surface of Gram-negative bacteria. NE killed wild-type, but not OmpA-deficient, E. coli . Also, whereas NE-deficient mice had impaired survival in response to E. coli sepsis, as compared to wild-type mice, the presence or absence of NE had no influence on survival in response to sepsis that had been induced with OmpA-deficient E. coli . These findings define a mechanism of nonoxidative bacterial killing by NE and point to OmpA as a bacterial target in host defense.