Structure of amylase-binding protein A of Streptococcus gordonii: a potential receptor for human salivary α-amylase enzyme

Amylase-binding protein A (AbpA) of a number of oral streptococci is essential for the colonization of the dental pellicle. We have determined the solution structure of residues 24-195 of AbpA of Streptococcus gordonii and show a well-defined core of five helices in the region of 45-115 and 135-145. ¹³Cα/β chemical shift and heteronuclear ¹⁵N-{¹H} NOE data are consistent with this fold and that the remainder of the protein is unstructured. The structure will inform future molecular experiments in defining the mechanism of human salivary α-amylase binding and biofilm formation by streptococci.