title: Specific binding of the human S protein (vitronectin) to streptococci, Staphylococcus aureus, and Escherichia coli.
abstract: Specific binding of the 125I-labeled human S protein (vitronectin) which has been shown to be identical with serum-spreading factor, was observed with group A, C, and G streptococci as well as with Staphylococcus aureus and Escherichia coli. The specific binding of S protein to group A, C, and G streptococci was high, whereas the binding to S. aureus and E. coli cultures was moderate. In contrast, group B streptococci and a number of other bacterial species tested did not interact with S protein. The binding of S protein to bacteria was saturable and could be inhibited only by unlabeled S protein but not by albumin. Trypsinization and heat treatment of bacteria destroyed the S-protein binding capacity for group G streptococci, S. aureus, and E. coli but not for group A and C streptococci. Likewise, unlabeled human fibronectin and heparin inhibited the binding of labeled S protein to group G streptococci, S. aureus, and E. coli, but did not influence the binding to group A and C streptococci. Double-reciprocal plots of S-protein binding to group G streptococci indicated that fibronectin inhibited the binding in a competitive manner, while heparin acts in a noncompetitive manner. Moreover, the binding of S protein to G streptococci could be partially by the synthetic peptide Gly-Arg-Gly-Asp-Ser, which contains the cell attachment site of S protein. Trypsin-treated S protein had similar binding activity as untreated S protein for group G streptococci, S. aureus, and E. coli, but showed reduced binding to group A and C streptococci. The present data are indicative of two different types of bacterial binding sites in S protein. The binding to group G streptococci, S. aureus, and E. coli is mediated in part through a domain in the S protein containing the sequence Arg-Gly-Asp, whereas a different site is responsible for the binding to group A and C streptococci.
mesh_terms: D001422:Bacterial Adhesion; D001665:Binding Sites; D001667:Binding, Competitive; D004926:Escherichia coli / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D009842:Oligopeptides / Q000378:metabolism; D010447:Peptide Hydrolases; D011485:Protein Binding; D013211:Staphylococcus aureus / Q000378:metabolism*; D013291:Streptococcus / Q000378:metabolism*; D019096:Vitronectin
chemical_list: D006023:Glycoproteins; D009842:Oligopeptides; D019096:Vitronectin; D010447:Peptide Hydrolases