ExPEC OmpT LL-37 Cleavage LC-MS

Colicin V (ColV)-like plasmids (ColVLPs) are virulence plasmids frequently carried by extra-intestinal pathogenic E. coli (ExPEC) that cause human and avian infection. ColVLPs encode OmpTp, an outer membrane protease with the capacity to cleave the antimicrobial peptide LL-37, which is expressed in the human urinary tract. Homologs of OmpTp also exist on the E. coli chromosome, and differences in enzyme activity and cleavage profiles are largely uncharacterised. For this section of the project, the capacity of each OmpT variant to cleave LL-37 is tested, by incubating isogenic E. coli strains expressing each OmpT homolog with LL-37, and subsequently using LC-MS to quantify LL-37 cleavage products.