Binding of K99 fimbriae of enterotoxigenic Escherichia coli to pig small intestinal mucin glycopeptides.

Binding of purified K99 fimbriae to cryostat sections of pig small intestine was detected. Binding sites were located in the mucus layer, but not in the submucosal connective tissue. High-Mr mucin glycopeptides from pig small intestine were found to bind to K99-fimbriated enterotoxigenic Escherichia coli, in contrast to non-fimbriated cells. Sialic acid specificity of K99 fimbriae was demonstrated by the significant reduction in binding upon desialylation of mucin glycopeptides. The binding was saturable and the dissociation constant was estimated to be 6 x 10(-7) M. Fimbriated bacteria were calculated to possess 2.3 x 10(3) binding sites per cell.