Synthetic peptides analogous to the fimbrillin sequence inhibit adherence of Porphyromonas gingivalis

Abstract

Fimbriae are important in the adherence of many bacterial species to the surfaces they eventually colonize. Porphyromonas (Bacteroides) gingivalis fimbriae appear to mediate adherence to oral epithelial cells and the pellicle-coated tooth surface. The role and contribution of fimbriae in the binding of P. gingivalis to hydroxyapatite (HAP) coated with saliva as a model for the pellicle-coated tooth surface were investigated. 3H-labeled P. gingivalis or the radioiodinated purified fimbriae were incubated with 2 mg of HAP beads coated with whole human saliva (sHAP) and layered on 100% Percoll to separate unbound from sHAP-bound components. The radioactivity of the washed beads was a measure of the bound components. The binding of P. gingivalis 2561 (381) cells and that of purified fimbriae were concentration dependent and saturable at approximately 108 cells and 40 ,ug of fimbriae added, respectively. The addition of fimbriae inhibited binding of P. gingivalis to sHAP beads by 65%, while the 75-kDa protein, which is another major surface component of P. gingivalis 2561, did not show significant inhibition, suggesting that the fimbriae are important in adherence. Encapsulated and sparsely fimbriated P. gingivalis W50 did not bind to sHAP beads. On the basis of the predicted sequence of the fimbrillin, a structural subunit of fimbriae, a series of peptides were synthesized and used to localize the active fimbrillin domains involved in P. gingivalis adherence to sHAP beads. Peptides from the carboxyl-terminal one-third of the fimbrillin strongly inhibited P. gingivalis binding to sHAP beads. Active residues within the sequence of inhibitory peptide 226-245 (peptide containing residues 226 to 245) and peptide 293-306 were identified by using smaller fragments prepared either by trypsin cleavage of the peptide 226-245 or by synthesis of smaller segments of peptide 293-306. Hemagglutinin activity, lectinlike binding, and ionic interaction did not seem to be involved in this binding since lysine, arginine, carbohydrates, and calcium ions failed to affect the binding of P. gingivalis. The observation that poly-L-lysine, bovine serum albumin, and defatted bovine serum albumin, even at high concentrations, only partially blocked the binding of P. gingivalis indicates that hydrophobic interactions are not the major forces involved in P. gingivalis binding to sHAP beads. Protease inhibitors such as EDTA, leupeptin, pepstatin, 1,10-phenanthroline, and phenylmethylsulfonyl fluoride did not interfere with the binding of P. gingivalis. However, the binding of P. gingivalis to trypsinor chymotrypsin-pretreated sHAP beads was reduced. Overall, these results suggest that fimbrillin has domains primarily confined in the carboxyl-terminal region of the protein which are responsible for binding P. gingivalis to surface-bound salivary components through specific protein-protein interactions. Specific fimbrillinmediated binding may be important in P. gingivalis attachment to oral surfaces coated with salivary components.

Synergistic biofilm formation byTreponema denticolaandPorphyromonas gingivalis

“…P. gingivalis mutants G102, G102W and JH007 are deficient in Arg-gingipain B (rgpB), Arg-gingipain plus Lys-gingipain (kgp) [21][22][23][24][25][26], and the major fimbriae [27][28][29][30], respectively. Attenuation of mutant G102 attachment to Streptococcus gordonii and Actinomyces naeslundii has been previously reported [25].…”

Anti-adhesion therapy of bacterial diseases: prospects and problems

“…The premise that peptides derived from a protein adhesin can serve as potent inhibitors of adhesion is supported by data from other experimental systems. For example, synthetic peptides mimicking a frag- ment of the ¢mbrillin adhesin of Porphyromonas gingivalis were found to inhibit adhesion of the organisms to hydroxyapatite [18,19]. Non-proteinaceous adhesins may also be useful for antiadhesion therapy, as shown in studies of the lipoteichoic acid (LTA)-mediated adhesion of group A and group B streptococci.…”

Involvement of Porphyromonas gingivalis fimbriae in adherence to Streptococcus gordonii

“…P. gingivalis fimbriae are considered important virulence determinants. Fimbriae can mediate adherence of the organism to saliva-coated hydroxyapatite, buccal epithelial cells and A. viscosus (6,9,18). Furthermore, immunization of germfree rats with P. gingivalis fimbriae protects against P. gingivalis-'mduced periodontal destruction (3).…”