Yersinia pestis Pla has multiple virulence-associated functions.

Our work indicates that Y. pestis Pla is a multifunctional surface protein. It is an efficient protease and also an adhesin and an invasin. The Salmonella homolog of Pla, PgtE, also has proteolytic and adhesive properties, whereas E. coli OmpT is only weakly adhesive, and its substrate specificity differs from that of Pla and PgtE. PgtE and OmpT do not mediate bacterial invasion into any of the human epithelial and endothelial cell lines tested. We are currently characterizing the mechanism and relevance of Pla-mediated invasion as well as the structural requirements of the other functions of Pla.