Taking the Starch out of Oral Biofilm Formation: Molecular Basis and Functional Significance of Salivary alpha-Amylase Binding to Oral Streptococci

alpha-Amylase-binding streptococci (ABS) are a heterogeneous group of commensal oral bacterial species that comprise a significant proportion of dental plaque microfloras. Salivary alpha-amylase, one of the most abundant proteins in human saliva, binds to the surface of these bacteria via specific surface-exposed alpha-amylase-binding proteins. The functional significance of alpha-amylase-binding proteins in oral colonization by streptococci is important for understanding how salivary components influence oral biofilm formation by these important dental plaque species. This review summarizes the results of an extensive series of studies that have sought to define the molecular basis for alpha-amylase binding to the surface of the bacterium as well as the biological significance of this phenomenon in dental plaque biofilm formation.