title: Soluble pilin of Neisseria gonorrhoeae interacts with human target cells and tissue.
abstract: Pili of Neisseria gonorrhoeae are phase-variable surface structures that mediate adherence to host target cells. Each pilus is composed of thousands of major pilus subunits, pilins, pilus-associated protein PilC, and possibly other components. Piliated and nonpiliated gonococcal clones may secrete a soluble smaller pilin (S-pilin) that is cleaved after amino acid 39 of the mature pilin protein. Here, purified S-pilin was found to migrate as a 61- to 64-kDa double band on nondenaturing gels, suggesting the formation of tetrameric S-pilin proteins with two isomeric forms. In situ studies of binding to formalin-fixed tissue sections demonstrated the binding of S-pilin to human tissue but not to tissue from mouse or rat organs, showing the presence of a human-specific receptor-binding domain within the pilin polypeptide. Pretreatment of the target tissues with proteinase K decreased gonococcal binding dramatically, whereas pretreatment with neuraminidase and meta-periodate, which cleave carbon-carbon linkages between vicinal hydroxyl groups in carbohydrates, did not affect gonococcal binding. In overlay assays, purified S-pilin bound to a band with a migration pattern and size similar to those of CD46, a cellular pilus receptor. Further, binding of N. gonorrhoeae to target cells and tissues could be blocked by both CD46 antibodies and purified S-pilin. These data argue that S-pilin interacts with a protein domain(s) of the CD46 receptor on human cells.
authors.affiliation: Microbiology and Tumor Biology Center, Karolinska Institutet, S-171 77 Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Rytkönen
authors.forename: L
authors.initials: L
authors.lastname: Johansson
authors.forename: V
authors.initials: V
authors.lastname: Asp
authors.forename: B
authors.initials: B
authors.lastname: Albiger
authors.forename: A B
authors.initials: AB
authors.lastname: Jonsson
mesh_terms: D000180:Acrylic Resins; D018829:Adhesins, Bacterial / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D036781:Fimbriae Proteins; D006801:Humans; D008297:Male; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000378:metabolism*; D018933:Pili, Sex / Q000378:metabolism*; D011489:Protein Denaturation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D014407:Tumor Cells, Cultured
chemical_list: D000180:Acrylic Resins; D018829:Adhesins, Bacterial; D015703:Antigens, CD; D001426:Bacterial Proteins; C497857:CD46 protein, human; C497860:Cd46 protein, rat; C497859:Mcp protein, mouse; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C074063:pilE protein, Neisseria gonorrhoeae; C016680:polyacrylamide gels; D036781:Fimbriae Proteins