MULTIPLE INTERACTIONS BETWEEN HUMAN VITRONECTIN AND STAPHYLOCOCCUS-AUREUS

Multiple interactions between human vitronectin and Staphylococcus aur eus strain V8 were observed. An upward-curved Scatchard plot indicated both high-affinity binding (K-d1=7.4.10(-10) M) with 260 binding site s per bacterial cell and moderate-affinity binding (K-d2 = 7.4.10(-8) M) with 5240 copies per cell. Negative cooperativity of this binding w as characterized by its Hill coefficient of less than unity (0.70 +/- 0.08). Up to 60% of the vitronectin-bacteria interaction was unaffecte d by high ionic strength (i.e., 2.4 M NaCl), and was not inhibited by highly-charged heparin oligosaccharides. Various oligosaccharides (4-2 0 monosaccharide units) generated by partial deaminative cleavage of h eparin were found to affect vitronectin binding to S. aureus. Short-ch ain-length oligosaccharides increase and long oligosaccharides inhibit vitronectin binding, in accordance with direct association of these s accharides with multimeric vitroectin. A protein having a molecular ma ss of 60 kDa was identified as a putative high-affinity staphylococcal vitronectin-binding protein. These results indicate that interaction of multimeric vitronectin, mostly present at extracellular matrix site s with multiple recognition sites on the S. aureus surface, may contri bute to bacterial colonisation.