Staphylococcus aureus autolysins interact with caprine vitronectin without involving the heparin binding domain and the second arginine-glycine-aspartic acid motif of the host protein.

Many bacteria exploit host proteins for their colonization. Vitronectin (Vn), present in the blood and extracellular matrix, is one such protein that acts as a bridge between the bacteria and the host tissues leading to infection. In this study, Vn binding protein of Staphylococcus aureus (COL strain) (SaVnBP) has been characterized as autolysin(s) based on mass spectrometry data and the ability of these proteins to degrade S. aureus substratum. Deletion of the heparin-binding domain (residues 341-380) from the Vn did not affect its ability to interact with SaVnBP. Similarly, change of R to A or D to A in the second arginine-glycine-aspartic (RGD2) motif of Vn had no negative effect on protein-protein interaction. These results imply that the primary heparin-binding site and the second RGD motif of caprine Vn may not be involved in the initial step of S. aureus colonization.