We are studying the function of adhesion to extracellular matrix components in the pathogenesis of Candida albicans. In vitro assays were developed to quantify the adhesion of C. albicans to immobilized fibronectin and proteolytic and recombinant fragments and to evaluate binding of soluble fibronectin and its fragments to C. albicans in suspension. In contrast to previous publications, we found that binding is not mediated by the Arg-Gly-Asp recognition sequence and is primarily mediated by the collagen-binding domain of fibronectin. A 30 kDa fragment of fibronectin containing the collagen binding domain is an active as intact fibronectin for binding to C. albicans. We have identified activating and inhibiting activities in growth media that regulate expression of the fibronectin rceptor in C. albicans. These are being purified to identify agents that may regulate the pathogenicity of C. albicans. After optimal activating conditions for expression are established, the receptor mediating binding to fibronectin will be isolated and characterized.
