Isolation and molecular characterisation of the POL3 gene from Candida albicans

In Saccharomyces cerevisiae, the CDC2 gene encodes the large subunit of DNA polymerase III, the analogue of mammalian DNA polymerase delta. We have isolated DNA fragments from a library of Candida albicans genomic DNA in the vector pRS316 that rescue temperature sensitive cdc2 mutations in S. cerevisiae. These fragments contain an ORF coding for a protein of 1038 aa with a predicted molecular mass of 118.8 kDa. The predicted protein shows homology to a number of eukaryotic DNA polymerases, with 62% identity over its length to the S. cerevisiae Cdc2 protein. It also contains a number of motifs which are characteristic of DNA polymerases in general and viral polymerases in particular, as well as the conserved motif which interacts with proliferating cell nuclear antigen. These results indicate that this gene is C. albicans POL3. Analysis of the expression of C. albicans POL3 revealed that the transcript is present throughout the mitotic cell cycle, which contrasts with the expression of S. cerevisiae CDC2.