ISOLATION OF A CANDIDA-ALBICANS DNA-SEQUENCE CONFERRING ADHESION AND AGGREGATION ON SACCHAROMYCES-CEREVISIAE

Candida albicans is an opportunistic pathogen which may give rise to s uperficial and systemic infections. In the present study, C albicans a dhesion was studied by expression of C. albicans DNA sequences encodin g adhesion functions in a nonadherent strain of Saccharomyces cerevisi ae. Adherent transformant cells of S. cerevisiae harbouring a C. albic ans genomic library cloned in a yeast-Escherichia coli shuttle vector were selected by using tissue culture-treated polystyrene as the attac hment substratum. One transformant exhibited enhanced adhesion to trea ted and untreated polystyrene as well as autoaggregation, unlike contr ol cells bearing the vector alone. Analysis of this clone revealed an insert of ca. 4.5 kb from C. albicans. Curing of the plasmid resulted in loss of adhesion and autoaggregation properties. A subclone bearing a reduced insert of 3.3 kb retained the ability to autoaggregate, to bind to treated and untreated polystyrene, and to adhere to buccal epi thelial cells, unlike appropriate controls. Further subcloning of the insert to 2.7- and 1.9-kb fragments resulted in incremental decreases in adhesion and autoaggregation, whereas smaller fragments did not con fer these properties. Hybridization of the 2.7-kb segment with C. albi cans and S. cerevisiae DNA confirmed its origin as a single-copy seque nce in the C. albicans genome as well as the absence of a homologous s equence in the genome of S. cerevisiae. The data suggest that the adhe sion and aggregation phenomena of the transformant cells are related t o expression of a C. albicans surface antigen encoded by the cloned DN A fragment.