Expression of the Candida albicans gene ALS1 in Saccharomyces cerevisiae induces adherence to endothelial and epithelial cells

Abstract

To identify genes encoding adhesins that mediate the binding of Candida albicans to endothelial cells, a genomic library from this organism was constructed and used to transform Saccharomyces cerevisiae. These transformed organisms were screened for adherence to endothelial cells, and a highly adherent clone was identified. The adherence of this clone to endothelial cells was over 100-fold greater than that of control S. cerevisiae transformed with the empty plasmid. This clone also exhibited enhanced adherence to epithelial cells. The C. albicans gene contained within this clone was found to be ALS1. These results indicate that ALS1 may encode a candidal adhesin.

FIG. 1

S. cerevisiae transformed with pYF-5 exhibits increase adherence to endothelial and epithelial cells. S. cerevisiae cells were transformed with either pYF-5 or the empty plasmid (pYesR). They were grown in either glucose (Glu) to suppress expression of the candidal gene or galactose (Gal) to induce expression of the candidal gene. Next, the adherence of these organisms to human umbilical vein endothelial cells (A) or FaDu epithelial cells (B) was determined. Results are the medians and interquartile ranges from at least four separate experiments, each performed in triplicate.

FIG. 2

Comparison of the published sequence of ALS1 (top) with the sequence of ALS1 contained in plasmid pYF-5 (bottom). GPI, glycosylphosphatidylinositol.