title: Characterization of an adhesion antigen of Streptococcus sanguis G9B.
abstract: An antigen possessing the attributes of an adhesion has been identified in Streptococcus sanguis G9B. Cell surface components were extracted from G9B and a spontaneously occurring nonadherent mutant of G9B, strain Adh-, with a 2 mM barbital buffer, pH 8.6. The extract of G9B but not of Adh- absorbed more than 80% of the adhesion-inhibitory activity of anti-G9B immunoglobulin G (IgG). Immunoblots revealed 80- and 52-kilodalton (kDa) antigens present in the G9B extract but not in the Adh- extract. Absorption of anti-G9B IgG with Adh- and G9B barbital extracts showed a correlation between the loss of the 80- and 52-kDa antibodies and the loss of adhesion-inhibitory activity. An antibody prepared against the 80-kDa antigen excised from sodium dodecyl sulfate-polyacrylamide gels recognized the 80- and 52-kDa antigens and another antigen of 62 kDa but did not inhibit adhesion. However, an antibody from an electroblot containing the native protein from which the 80-kDa and related antigens were derived (the 80-kDa antigen complex) inhibited adhesion to the same extent as anti-G9B IgG. Periodate oxidation of the G9B barbital extract modified the 80-kDa antigen complex and resulted in the loss of 40% of its absorbing activity. The barbital extract also contained an endogenous enzyme responsible for producing the 62- and 52-kDa antigens from the 80-kDa protein and which, under optimal conditions, degraded the antigen completely, resulting in the loss of antibody-absorbing activity. The 80-kDa antigen complex has a molecular mass of more than 200 kDa in native polyacrylamide gels and a pI of 4.1 to 4.8. These observations suggest that the adhesion antigen in S. sanguis G9B is a large glycoprotein from which an 80-kDa antigen complex is derived.
authors.affiliation: Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104.
authors.forename: R J
authors.initials: RJ
authors.lastname: Lamont
authors.forename: B
authors.initials: B
authors.lastname: Rosan
authors.forename: C T
authors.initials: CT
authors.lastname: Baker
authors.forename: G M
authors.initials: GM
authors.lastname: Nelson
mesh_terms: D000042:Absorption; D018829:Adhesins, Bacterial; D000818:Animals; D000954:Antigens, Surface / Q000276:immunology / Q000302:isolation & purification*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D001462:Barbital; D001666:Binding Sites, Antibody; D004591:Electrophoresis, Polyacrylamide Gel; D007118:Immunoassay; D007525:Isoelectric Focusing; D008562:Membrane Glycoproteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D010504:Periodic Acid; D011817:Rabbits; D013298:Streptococcus sanguis / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D000954:Antigens, Surface; D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D010504:Periodic Acid; D001462:Barbital; C009288:metaperiodate