Candida glabrata encodes a longer variant of the mating type (MAT) alpha2 gene in the mating type-like MTL3 locus, which can form homodimers

Abstract

"The fungal pathogen Candida glabrata is a haploid asexual yeast. Candida glabrata contains orthologs of the genes that control mating and cell-type identity in other fungi, which encode putative transcription factors localized in the MAT locus in Saccharomyces cerevisiae or MTL in other fungi. Candida glabrata contains three copies of the CgMTL locus but only CgMTL1 correctly expresses the information encoded in it. CgMTL1 can encode the Cga1 gene (a information), or the Cgalpha1 and Cgalpha2 genes (alpha information). CgMTL2 contains an identical copy of the Cga1 gene. CgMTL3 contains an identical copy of the Cgalpha1 gene but a longer variant of the Cgalpha2 gene that we termed Cgalpha3. In S. cerevisiae diploid cells, that express Sca and Scalpha information, Sca1 and Scalpha2 proteins form a heterodimer, which represses genes expressed only in haploid cells and some genes involved in stress response. We constructed C. glabrata strains that simultaneously express Cga1 and Cgalpha2 or Cga1 and Cgalpha3 genes. We did not find any phenotype in these strains when grown under a large variety of stress and nutritional conditions. However, we detected an interaction between Cga1 and Cgalpha2 but not between Cga1 and Cgalpha3 by Bimolecular Fluorescence Complementation and co-immunoprecipitation assays."