The ability of Staphylococcus epidermidis to elicit disease in the host is dependent on its attachment to tissue and serum-protein covered biomaterials. In prior studies it was shown that once established onto a surface, this organism can form polysaccharide-encased biofilms. However, the elements necessary for the initial attachment step are not well characterized. I postulate that cell-surface proteins are involved in the initial phase of S. epidermidis adherence to host tissue and biomaterials. Therefore, I propose to identify and characterize the proteins necessary for S. epidermidis attachment to collagen and fibronectin. To accomplish these goals, I intend to, a) identify, clone and sequence novel S. epidermidis collagen- and fibronectin-adhesin genes, b) define the ligand binding domain within the collagen-binding protein, c) determine the adhesin binding site in collagen, and c) analyze the molecular interactions between the adhesin and collagen. An understanding of the S. epidermidis adhesins structure and their molecular interactions with their ligands may lead to the development of therapeutic agents that could prevent biomaterials infections.