TITLE:
Streptococcal SspB Peptide Analog Inhibits Saliva-Promoted Adhesion and Biofilm Formation of Streptococcus mutans
AUTHORS:
Tatsuro Ito, Takahiro Ichinosawa, Nana Ikematsu-Ito, Chihiro Watanabe, Takehiko Shimizu
KEYWORDS:
SspB, Biofilm, Streptococcus mutans, Saliva, gp340
JOURNAL NAME:
Open Journal of Stomatology,
Vol.6 No.3,
March
30,
2016
ABSTRACT: Background: Streptococcus gordonii, a pioneer colonizer of dental plaque biofilm, expresses surface protein adhesin SspB by which the bacteria bind to salivary agglutinin (gp340). SspB has extensive homology with PAc, a surface adhesin of Streptococcus mutans. Hence, SspB of S. gordonii competes with PAc of S. mutans for the same niche environment in the salivary pellicles. The aim of this study was to develop anti-adherence agents that enabled us to control cariogenic biofilms by using the streptococcal SspB peptide analog SspB (A4K-A11K). Methods: First, we performed ELISA to determine the S. mutans-saliva interaction and saliva-binding activities of SspB (A4K- A11K). The inhibitory effects of SspB (A4K-A11K) were then evaluated by examining S. mutans adhesion to saliva-coated hydroxyapatite disks (s-HA). To determine peptide interference with biofilm formation, S. mutans biofilms were quantified by counting CFUs on MS agar plates and by measuring the absorbance at 492 nm of safranin-stained biofilms on s-HA. Results: Saliva, particularly salivary gp340 peptide, promoted adherence of S. mutans to polystyrene surfaces. SspB (A4K-A11K) significantly bound to saliva and inhibited the adhesion of S. mutans to s-HA without bactericidal activity. Furthermore, biofilms of S. mutans on s-HA were successfully reduced by pretreatment with SspB (A4K-A11K). Conclusion: SspB (A4K-A11K) peptide competitively blocked S. mutans adhesion to experimental pellicles through SspB-gp340 interaction, thereby inhibiting biofilm formation. These findings will contribute to the control cariogenic biofilms.