A CANDIDA-ALBICANS HOMOLOG OF CDC25 IS FUNCTIONAL IN SACCHAROMYCES-CEREVISIAE

We have cloned, by functional complementation of the cdc25-2 mutation of Saccharomyces cerevisiae, a homolog of CDC25 from the pathogenic yeast Candida albicans. The new gene, named CSC25, codes for a 1333-amino-acid protein. The full length gene, as well as a truncated form coding for 795 amino acids, suppresses the thermosensitive phenotype of cdc25ts mutants. Biochemical analysis has shown that Csc25 activates the Ras/adenylyl cyclase pathway in S. cerevisiae at a rate two to three times faster than Cdc25, under the same conditions. The C-terminal domain of Csc25 is highly similar to the C-terminal domain of Cdc25, to almost the same extent as the C-terminus of the endogenous Cdc25 homolog Sdc25. We show that polyclonal anti-Cdc25 antibodies interact with Csc25 expressed in S. cerevisiae. In addition to the full length protein (almost-equal-to 150 kDa), we have found a almost-equal-to 50-kDa polypeptide which seems to include the C-terminus of the CSC25 gene product.