Porphyromonas gingivalis Fimbriae Mediate Coaggregation with Streptococcus oralis through Specific Domains

Abstract

Fimbriae are major adhesive components on the cell surface of Prophyromonas gingivalis. In this study, we evaluated the role of fimbriae in coaggregation with Streptococcus oralis. Fimbriae purified from P. gingivalis competitively inhibited the coaggregation by 100% at a concentration of 50 micrograms/mL. On the other hand, the same amount of lipopolysaccharide isolated from P. gingivalis was inhibited by only 25% of the level of the fimbriae. A fimA-inactivated mutant of P. gingivalis failed to show distinct coaggregation activity. Fimbriae added to a solution of various strains of streptococci caused their self-aggregation at a concentration of 10 to 30 micrograms/mL. The self-aggregation induced by fimbriae was inhibited by lambda-arginine (20 to 40 mM/L). Iodinated fimbriae reacted with S. oralis cells immobilized on the nitrocellulose membrane, and 100 degrees C heating of the cells diminished the binding abilities. Recombinant fimbrillin (r-Fim, corresponding to whole residues 1 to 337 of native fimbrillin) of P. gingivalis also showed 100% inhibition of the coaggregation. The r-Fim variant (residues 1 to 286) lacking the C-terminal 51 residues was as inhibitory as r-Fim. However, the variant (residues 1 to 265) without the C-terminal 72 residues lost 77% of the inhibitory activity. These findings suggested that residues 266 to 286 contain a domain involved in the coaggregation of P. gingivalis with S. oralis. Inhibition by three polypeptides corresponding to residues 266 to 286, 266 to 337, and 287 to 337 was studied. Peptides 266 to 286 and 266 to 337 inhibited by 96 and 100%, respectively, at a concentration of 1.5 nmol/mL. Peptide 287 to 337 also showed a significant inhibitory effect but to a slightly lesser extent than that of peptide 266 to 286. P. gingivalis fimbriae appear to be involved in coaggregation with streptococci, probably through an adhesive protein molecule(s) of the latter, and the fimbriae possess several domains in the C-terminal residues 266 to 337 for interaction with S. oralis.

Involvement of minor components associated with the FimA fimbriae of Porphyromonas gingivalis in adhesive functions

“…PBS adjusted to pH 6.0 was used throughout the autoaggregation assays. The OD 550 value of the cell suspension was measured and adjusted by dilution with PBS to 1.0, which corresponds to 1.0610 8 cells ml 21 (Amano et al, 1997). Aliquots (2 ml each) in test tubes (13 mm diameter) were then shaken at room temperature at a speed of 120 strokes min…”

Coaggregation of Porphyromonas gingivalis and Prevotella intermedia

“…to coaggregate with a number of oral bacteria (I,8,II,12,17,20,(33)(34)(35). However, there have been very few studies to investigate the factors and mechanisms for coaggregation.…”

Identification of the Binding Domain of Streptococcus oralis Glyceraldehyde-3-Phosphate Dehydrogenase for Porphyromonas gingivalis Major Fimbriae

“…Additionally, P. gingivalis FimA fimbriae have been shown to interact with epithelial cells (17), cultured human fibroblasts (14), and salivary proteins (2), which indicates that P. gingivalis FimA fimbriae play an important role as a main adhesive component in bacterial colonization. Previously, we reported that P. gingivalis FimA fimbriae bind to Streptococcus oralis, an early colonizer in dental plaque (3).…”