Binding of heparin-binding form of
vitronectin to Staphylococcus aureus was inhibited completely by heparin or by the same form of
vitronectin. The binding was inhibited only to about 50% by the non-heparin-binding form of
vitronectin, indicating an apparent involvement of the heparin-binding properties in the interaction between vitronectin and S. aureus. This was supported by experiments in which a synthetic peptide (Ala347-Arg361, comprising heparin-binding
consensus sequences) was found to partly inhibit bacterial adherence to immobilized
vitronectin. A bacterial cell surface protein could bind to the quinquedecapeptide, but not to the highly charged peptides consisting entirely of arginine or lysine, immobilized on microtiter plates and the binding could be competitively inhibited by an excess of soluble peptide. Direct binding of radiolabeled peptide to bacterial cells was also demonstrated, which was rapid, saturable, and pH-dependent. Furtherly a bacterial surface protein having molecular mass of 60 kDa was isolated by affinity chromatography on a quinquedecapeptide-HiTrap-NHS column. Our data suggest that the heparin-binding properties of vitronectin play a role in bacterial recognition.