Isolation and characterization of a 60-kilodalton salivary glycoprotein with agglutinating activity against strains of Streptococcus mutans

Abstract

A bacterial agglutinin specific for strains of Streptococcus mutans was isolated from human saliva. Physiochemical analyses showed the agglutinin to be a glycoprotein with a molecular weight of 60,000. The agglutinin aggregated four of the eight strains of Streptococcus mutans tested but did not aggregate the strains of Streptococcus salivarius, Streptococcus sanguis, and Streptococcus mitis tested. Chemical modification of carbohydrate moieties of the agglutinin with sodium metaperiodate had no effect on aggregation, whereas modification of the polypeptide portion with trypsin abolished aggregating activity. A set of five murine hybridoma antibodies was employed to further analyze the agglutinin. Two carbohydrate-specific antibodies, directed against D-mannose and N-acetylgalactosamine moieties, respectively, failed to block agglutinin- or whole saliva-mediated aggregation of S. mutans cells. In contrast, two antibodies directed against pronase-sensitive antigenic sites blocked both agglutinin- and saliva-mediated aggregation of S. mutans cells. Western blot analysis with the agglutinin-specific hybridoma antibodies demonstrated the agglutinin in whole saliva and in artificial tooth pellicles formed on hydroxyapatite beads incubated with saliva. These results suggest that a 60-kilodalton glycoprotein of human saliva is a bacterial agglutinin with specificity for certain strains of S. mutans. They further suggest that aggregation is mediated by polypeptide rather than carbohydrate determinants of the glycoprotein.

Adherence of Porphyromonas (Bacteroides) gingivalis to Streptococcus sanguis in vitro

“…Although this assay was rapid and convenient for initial screening for interbacterial adherence activity of numerous bacterial pairs suspended in buffered salts solutions, it proved to be less appropriate for studies directed at characterizing the modulating effects of host components such as saliva and serum. These host secretions contain immunoglobulins and other constituents that can bind to oral bacteria and cause agglutination (1,7,16,19,21). Preliminary experiments with radiolabeled streptococci indicated that inclusion of saliva and serum in assay mixtures caused a significant (20%) increase in the numbers of bacteria retained by the filter membrane, although agglutination of these To facilitate the distinction between host-induced bacterial agglutination and true interbacterial adherence, a solidphase assay was devised in which viable S. sanguis is coupled to CNBr-agarose.…”

Characterization of salivary alpha-amylase binding to Streptococcus sanguis

“…Void volume materials were used for the subsequent studies. The specific activities (counts per minute per microgram of protein) obtained were 3.5 x 106 for HSMSL, 2.9 x 106 for HPS, 3.5 x 106 for sIgA, and 1 x 106 to 3 x 106 (5.5 x 104 to 16.5 x 104 cpm/pmol) for o-amylase.…”

“…been shown to interact with various oral bacteria in vitro. These include mucins (20,28,37,38), proline-rich glycoprotein (5, 56), secretory immunoglobulin A (sIgA) (40, 64), a fucose-rich glycoprotein from parotid saliva (16), lysozyme (25, 52), P2-microglobulin (15), and others (3,4). The goal of the present study was to ascertain to what extent salivary components interact with S. sanguis and other bacteria and to determine the mechanism(s) responsible for their binding to the bacterial surface.…”

Inhibitory effect of saliva from secretors and non-secretors on binding of meningococci to epithelial cells

“…Among the non-immune defences against bacterial adherence in the oral cavity, there are naturally secreted high molecular weight glycoproteins that might behave as receptor analogues, either aggregating [9,16] or binding to bacteria [17] reducing the number of organisms available to attach to specific receptors. Further assessment of these carbohydrate containing compounds is required as there appears to be more inhibitory activity in the salivary components of secretors compared with non-secretors.…”