title: Inhibition of glucosyltransferase activities of Streptococcus mutans by a monoclonal antibody to a subsequence peptide.
abstract: Preliminary analysis indicated that a 19-amino-acid peptide sequence (435 to 453 of GtfC) within a highly conserved region of the glucosyltransferases of the cariogenic streptococci might be functionally important (J.-S. Chia, S.-W. Lin, T.-Y. Hsu, J.-Y. Chen, H.-W. Kwan, and C.-S. Yang, Infect. Immun. 61:1563-1566, 1993). To obtain antipeptide monoclonal antibodies (MAbs), the 19-amino-acid peptide was conjugated to bovine serum albumin and used as an antigen in BALB/c mice. Six immunoglobulin G-secreting hybridoma clones, CJSm18-S1 to -S6, specifically reacted with this peptide and with purified GtfC and GtfD but not with bovine serum albumin in an enzyme-linked immunosorbent assay. The concentrated hybridoma supernatant of all six MAbs inhibited GtfC enzymatic activity but failed to inhibit GtfD, although GtfD contains the same peptide sequence. Further analysis of a purified immunoglobulin G2b MAb from one of the clones, CJSm18-S3, confirmed that this MAb specifically inhibited GtfC enzymatic activity for insoluble-glucan synthesis in a dose-dependent manner. CJSm18-S3, even at high concentrations, had no effect on GtfD, which synthesizes water-soluble glucan exclusively. Furthermore, the in vitro sucrose-dependent adherence of Streptococcus mutans was also inhibited by CJSm18-S3 in a dose-dependent manner. Our results indicate that the peptide containing the N-terminal conserved region of glucosyltransferases is functionally important for both enzymatic activity and bacterial adherence.
authors.affiliation: Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Republic of China.
authors.forename: J S
authors.initials: JS
authors.lastname: Chia
authors.forename: R H
authors.initials: RH
authors.lastname: Lin
authors.forename: S W
authors.initials: SW
authors.lastname: Lin
authors.forename: J Y
authors.initials: JY
authors.lastname: Chen
authors.forename: C S
authors.initials: CS
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001422:Bacterial Adhesion; D017124:Conserved Sequence; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology / Q000502:physiology*; D013295:Streptococcus mutans / Q000201:enzymology* / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D005964:Glucosyltransferases