The PilC adhesin of the Neisseria type IV pilus-binding specificities and new insights into the nature of the host cell receptor.
Type IV pili of Neisseria gonorrhoeae and Neisseria meningitidis mediate the first contact to human mucosal epithelial cells, an interaction which is also critical for the interaction with vascular endothelial cells. The PilC proteins have been characterized as the principal pilus-associated adhesin. Here we show that PilC2 exhibits a defined cell and tissue tropism, as it binds to human epithelial and endothelial cell lines, but not to human T cells or fibroblasts. Piliated gonococci and PilC2 exhibit similar patterns of binding to human epithelial and endothelial cells, supporting the function of PilC as the key pilus adhesin. Although CD46 has previously been suggested to be a pilus receptor, several observations indicate that neisserial type IV pili and the pilus adhesin PilC2 interact with epithelial cells in a CD46 independent manner. Biochemical approaches were used to characterize the nature of host cell factors mediating binding of piliated gonococci and PilC2 protein. Our data indicate that the putative host cell receptor for gonococcal pili and the PilC2 pilus adhesin is a surface protein. Glycostructures were found to not be involved in binding. Moreover, we observed the uptake of purified PilC2 protein together with its receptor via receptor-mediated endocytosis and subsequent receptor re-exposure on the cell surface. Our data support the existence of a specific pilus receptor and provide intriguing information on the nature of the receptor.
Kirchner
Marieluise
M
Department of Molecular Biology, Max Planck Institute for Infection Biology, Schumannstrasse 21/22, 10117 Berlin, Germany.
Meyer
Thomas F
TF
D018829:Adhesins, Bacterial / Q000378:metabolism*; D001422:Bacterial Adhesion / Q000502:physiology*; D002460:Cell Line; D004705:Endocytosis; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D036781:Fimbriae Proteins / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D009344:Neisseria gonorrhoeae / Q000378:metabolism*; D011485:Protein Binding; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D018829:Adhesins, Bacterial; D008565:Membrane Proteins; D036781:Fimbriae Proteins