A CANDIDA-ALBICANS SURFACE-ANTIGEN MEDIATING ADHESION AND AUTOAGGREGATION IN SACCHAROMYCES-CEREVISIAE

In a previous study (M. Barki, Y. Koltin, M. Yanko, A. Tamarkin, and M . Rosenberg, J. Bacteriol. 175:5683-5689, 1993), a 3.3-kb DNA fragment from Candida albicans which confers adhesion and autoaggregation in S accharomyces cerevisiae was isolated and partially characterized. In t his report, evidence is presented that the adhesion-autoaggregation ph enotype observed in S. cerevisiae cells transformed with the candidal DNA fragment is due to expression of a C. albicans surface antigen. Ra bbit antiserum, prepared against transformant S. cerevisiae cells, was adsorbed with S. cerevisiae bearing the vector alone. Immunofluoresee nce micrography showed that the adsorbed antiserum bound to the surfac e of transformant S. cerevisiae cells as sell as to C. albicans cells, but only marginally to the S. cerevisiae control. The adsorbed antise rum specifically inhibited autoaggregation of transformant cells. Furt her adsorption of the antiserum with transformant cells eliminated bot h inhibition and immunofluorescence. Autoaggregative activity and immu nofluorescence of transformant cells were abolished following proteoly tic treatment. Western blot (immunoblot) analysis of candidal extracts revealed that the absorbed antiserum recognized a major candidal anti gen of ca. 30 kDa which was present on both yeast-phase and germ tube cells. The data suggest that the observed adhesion-autoaggregation phe notype is due to the presence of a specific candidal antigen on the ou ter surface of the transformant cells.