The ability to switch from yeast to hyphal forms is essential for Candida albicans virulence. This morphological switch involves the expression of hyphal-specific genes under the control of transcriptional factors. To contribute to the discovery of hyphal-specific genes, we used a differential screening method where clones of a genomic DNA library were hybridized with yeast and hyphal cDNA probes. Two clones with increased expression in hyphae were selected for study. Sequencing these clones, we found that they encoded two important metabolic genes, CaHXT7 (high-affinity hexose transporter) and CaYLL34 (member of the AAA ATPase family). CaHXT7 and CaYLL34 ORFs were completely determined. Analyses of the putative proteins show that: (1) CaHxt7p has one hexose transporter domain and (2) CaYll34p has two AAA ATPase domains. These results show, for the first time, increased expression of metabolic genes in C. albicans hyphae. Also, because the proteins encoded by CaHXT7 and CaYLL34 may be necessary for the switching to hyphae, they could be new targets for antifungal drugs.
Differential screening; Candida albicans; HXT7; YLL34
