Identification and preliminary characterization of a Streptococcus sanguis fibrillar glycoprotein

Abstract

Cell surface fibrils could be released from Streptococcus sanguis 12 but not from strains 12na or N by freeze-thawing followed by brief homogenization. Fibrils were isolated from the homogenate by ultracentrifugation or ammonium sulfate precipitation. Electron microscopy demonstrated the presence of dense masses of aggregated fibrils in these preparations. Under nondenaturing conditions, no proteins were seen in polyacrylamide gel electrophoresis (PAGE). Sodium dodecyl sulfate (SDS)-PAGE analysis revealed a single band stained with Coomassie blue and periodic acid Schiff stain with a molecular weight in excess of 300,000. The protein has been given the name long-fibril protein (LFP). The molecule was susceptible to digestion with subtilisin, pronase, papain, and trypsin, but was unaffected by chymotrypsin or muramidases. Attempts to dissociate the protein into smaller subunits with urea, guanidine, sodium thiocyanate, and HCl were unsuccessful. Gel filtration on a column of Sephacryl S-400 in the presence of 2% SDS resulted in elution of the protein at the void volume. Antibody raised against the LFP excised from an SDS-PAGE gel reacted with long fibrils on the surface of strain 12 and with isolated fibrils by an immunogold labeling technique. Monoclonal antibody reactive with LFP in SDS-PAGE also reacted with fibrils present on the cell. Antisera raised against the fibrils inhibited adherence to saliva-coated hydroxyapatite.

Description of Two Morphotypes of Peptostreptococcus micros

“…Streptococcus salivanus expresses three different classes of fibrils, which have distinct adhesive functions (34,35). It has been suggested that subunits of the fibrils of these oral streptococci range in size from 70 to 90 kDa (19) to more than 300 kDa (20). These different fibrils have distinct hydrophobic characteristics.…”

“…Streptococcus sanguis, for example, has adhesins (5, 13), fibrillar glycoproteins (20), and cell surface components related to aggregation, adherence, and hydrophobicity (19). Streptococcus salivanus expresses three different classes of fibrils, which have distinct adhesive functions (34,35).…”

Saliva-Bacterium Interactions in Oral Microbial Ecology

“…Interestingly, the size of these components resembles those of the sHA adhesin complex described by Rosan and co-workers (Lamont et al, 1988b;Rosan et al, 1988) that interacted with a 73-kDa salivary component from submandibular saliva but were not expressed by a nonadherent mutant of the parent strain (Lamont et al, 1988b). In addition to these components, a high-molecularweight sialic-acid binding component (SSP5) has been proposed to mediate the binding of the parotid agglutinin to strains of S. gordonii Demuth et al, 1988;Demuth et al, 1990a;Morris et al, 1985;Morris et al, 1987). SSP5 has been shown to have sequence homology with a family of surface proteins first detected in S. mutans (AgI/Il, see below).…”

Polypeptides associated with tufts of cell-surface fibrils in an oral Streptococcus

“…Binding of streptococci t o experimental salivary pellicle may be influenced by the presence of cell-surface fibrils (Gibbons et al, 1983;Morris et al, 1987) or fimbriae (Fives-Taylor & Thompson, 1985), and ability to coaggregate with other oral genera was found to correlate with surface structure morphology (Handley et al, 1985). For strains of Streptococcus crista producing polar tufts of fibrils (Handley e t al., 1991), electron microscopic evidence suggests that these structures are involved in the formation of…”