Roles of PilC and PilE proteins in pilus-mediated adherence of Neisseria gonorrhoeae and Neisseria meningitidis to human erythrocytes and endothelialand epithelial cells

Unlike other type 4 pill, the neisserial pill consist of at least two disti nct proteins, the highly variable major subunit PilE forming the pilus fibe r and the tip-associated adhesin PilC. PilC protein purified either from go nococci or from Escherichia coli interacted with different human epithelial cell lines, primary epithelial and endothelial cells. The binding of PilC protein efficiently prevented the attachment of piliated Neisseria gonorrho eae and Neissaria meningitidis to these cell types. Fluorescent beads coate d with pill prepared from piliated wild-type N. gonorrhoeae also adhered to these cells, in contrast to beads coated with pill prepared from a piliate d PilC-deficient mutant. In the latter case, the binding of fluorescent bea ds was restored after pretreatment of the pilus-loaded beads with purified PilC, Piliated wild-type N. gonorrhoeae, the piliated PilC-deficient mutant , and N. gonorrhoeae pill assembled in Pseudomonas aeruginosa agglutinated human erythrocytes, while nonpiliated gonococci did not. Consistently, puri fied PilC did not agglutinate or bind to human erythrocytes, suggesting tha t N. gonorrhoeae PilE is responsible for pilus-mediated hemagglutination.