Hemoglobin differentially induces binding of Candida, Trichosporon, and Saccharomyces species to fibronectin

Fibronectin (FN) is an abundant host protein that is specifically recognized by several pathogenic yeasts. Binding of FN in solution to Candida, Trichosporon, and Saccharomyces species is increased 20- to 110- fold by growth in medium containing hemoglobin, but specific adhesion to immobilized FN is increased only in Candida albicans, Candida tropicalis, Candida krusei, and Candida glabrata. Hemoglobin induces both specific and nonspecific binding of soluble FN. Nonspecific binding accounts for all of the enhancement in Trichosporon beigelii and Saccharomyces cerevisiae, but the Candida species possess a saturable, high-affinity binding site for FN that is induced by hemoglobin. Induction of displaceable soluble FN binding correlates with the ability of hemoglobin to regulate adhesion to immobilized FN, since hemoglobin does not induce adhesion of S. cerevisiae or T. beigelii to immobilized FN. Regulation by hemoglobin of FN binding to Candida species may therefore be an important factor in the pathogenesis in these yeast infections.