Isolation and characterization of the Candida albicans MOT2 gene.

A putative Candida albicans homologue of Saccharomyces cerevisiae MOT2 (modulator of transcription) has been cloned and analyzed. A cDNA fragment corresponding to a portion of S. cerevisiae MOT2 was used to isolate a similar C. albicans gene (CaMOT2). CaMOT2 is comprised of two exons of 50 bp and 1,714 bp, respectively, with a single 82 bp intron located near the 5' end of the gene. The gene encodes a protein (CaMot2p) with an estimated mass of 67 kDa. The 5' region of the gene shows sequence homology with S. cerevisiae MOT2, whereas no significant similarity was observed in the 3' region. Similarly, the N-terminal portion of C. albicans Mot2p exhibits approximately 80% homology with S. cerevisiae Mot2p, while no significant homology to any known protein was observed in the carboxy-terminal half of the C. albicans protein. The N-terminal portion of CaMot2p contains a cysteine-rich domain (amino acids 18-62). The distribution of the cysteine residues identifies CaMot2p as a zinc-finger protein. The data suggest two potential Zn-binding sites, similar to the arrangement found in S. cerevisiae. Reverse-transcriptase polymerase chain reaction was used to compare the level of CaMOT2 expression between C. albicans grown in vitro and growth during in vivo infection in the rat model of oral candidiasis. The results showed CaMOT2 is down-regulated during growth in the rat oral cavity compared to in vitro culture. Although the function of C. albicans MOT2 has not been determined, comparison to S. cerevisiae MOT2 suggests the gene product may act as a general negative regulator.