Identification of a putative transcription factor in Candida albicans that can complement the mating defect of Saccharomyces cerevisiae ste12 mutants

We have isolated an acid proteinase-related gene, ACPR, from Candida albicans using a partial clone (Ganesan, K, Banerjee, A., and Datta, A. (1991) Infect. Immun. 59, 2972-2977) as a probe. Sequencing of the full-length gene revealed an open reading frame that can encode a protein of 699 amino acids. The deduced NH2-terminal amino acid sequence did not correspond with that determined from the purified secretory acid proteinase; however, the encoded protein is antigenically related to secretory acid proteinase and has a putative active site for acid proteinase. Interestingly, the amino acid sequence of the NH2-terminal 215 residues of Acprp is highly similar to the DNA binding domain of Ste12p of Saccharomyces cerevisiae. Gel retardation experiments showed that this region of Acprp, like Ste12p, could bind to S. cerevisiae pheromone response elements, suggesting that Acprp has a function similar to Ste12p. Chimeric constructs composed of S. cerevisiae STE12 and C. albicans ACPR genes complemented the mating defect of S. cerevisiae a or alpha ste12 mutants. Our results suggest the presence of a signal transduction system in C. albicans similar to that of S. cerevisiae mating pathway.