Molecular Interaction of the Analogous Peptide SspB (390-T400K-402) derived from Streptococcus gordonii Surface Protein Peptide with Periodontal Bacteria

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The initial stages of dental biofilm formation involved the adherence of early colonizing organisms such as Streptococcus gordonii on the saliva-coated tooth surface. The surface protein SspB of S. gordonii is known to play a role in adherence to salivary protein and mediates coaggregation with other bacteria. We previously demonstrated that the analogous SspB peptide, SspB(390-T400K-402), effectively bound to salivary agglutinin peptide SRCRP2 (scavenger receptor cysteine-rich domain peptide 2). To investigate molecular interaction of supra- and sub-gingival dental plaque biofilm formation among streptococci, periodontal bacteria, and salivary agglutinin as a unit, we examined the binding activity of the SspB(390-T400K-402)peptide to periodontal bacteria. The binding activity of SspB(390-T400K-402)was detected by ELISA. The SspB(390-T400K-402) peptide bound to P. gingivalis ATCC 33277, F. nucleatum ATCC 23726, and F. nucleatum #20. This binding was reduced by the presence of whole saliva; however, the presence of SRCRP2 enhanced the binding of the SspB peptide to these bacteria. These findings suggest that the binding ability of S. gordonii to these periodontal bacteria may provide,either directly(by attachment to P. gingivalis Mfa1)or indirectly(by attachment to F. nucleatum), a support system for the colonization and the biofilm formation of periodontal bacteria.