title: Structure, function and immunogenicity of streptococcal antigen I/II polypeptides.
abstract: The antigen I/II family of cell-surface-anchored polypeptides in oral streptococci are structurally complex multi-functional adhesins, with multiple ligand-binding sites. Discrete regions within these polypeptides bind human salivary glycoproteins, other microbial cells, and calcium. Sequences within the N-terminal region bind preferentially fluid-phase glycoproteins, while the C-terminal half of the polypeptide contains species-specific adhesion-mediating sequences that bind surface-immobilized glycoproteins. These features may assist streptococcal adhesion to oral surface receptors despite the presence of excess fluid-phase receptors. Immunological studies reveal an array of T-cell and B-cell epitopes presented by antigen I/II polypeptides and suggest the occurrence of natural suppression of human antibodies to the adhesion-mediating sequences. The functional and immunological properties of antigen I/II proteins may account to a major extent for the success of oral streptococci colonizing and surviving within the human host.
authors.affiliation: Department of Oral Biology and Oral Pathology, University of Otago, Dunedin, New Zealand. howard.jenkinson@stonebow.otago.ac.nz
authors.forename: H F
authors.initials: HF
authors.lastname: Jenkinson
authors.forename: D R
authors.initials: DR
authors.lastname: Demuth
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics* / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology*; D001426:Bacterial Proteins; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013291:Streptococcus / Q000235:genetics* / Q000276:immunology* / Q000502:physiology
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D008562:Membrane Glycoproteins; C055764:S-layer proteins