title: Four mating-type genes control sexual differentiation in the fission yeast.
abstract: The mating-type region of fission yeast consists of three components, mat1, mat2-P and mat3-M, each separated by 15 kb. Cell-type is determined by the alternate allele present at mat1, either P in an h+ or M in an h- cell. mat2-P and mat3-M serve as donors of information that is transposed to mat1 during a switch of mating type. We have determined the nucleotide sequence of each component of mat. The P and M specific regions are 1104 and 1128 bp, respectively, and bounded by sequences common to each mating-type cassette (H1; 59 bp and H2; 135 bp). A third sequence is present at mat2-P and mat3-M but absent at mat1 (H3; 57 bp), and may be involved in transcriptional repression of these cassettes. mat1-P and mat1-M each encode two genes (Pc; 118 amino acids, Pi; 159 amino acids, Mc; 181 amino acids and Mi; 42 amino acids). Introduction of opal or frame-shift mutations into the open-reading-frame of each gene revealed that Pc and Mc are necessary and sufficient for mating and confer an h+ or h- mating type respectively. All four genes are required for meiotic competence in an h+/h- diploid. The transcription of each mat gene is strongly influenced by nutritional conditions and full induction was observed only in nitrogen-free medium. The predicted product of the Pi gene contains a region of homology with the homeobox sequence, suggesting that this gene encodes a DNA binding protein that directly regulates the expression of other genes.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004271:DNA, Fungal / Q000235:genetics; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D005801:Genes, Homeobox; D049770:Genes, Mating Type, Fungal; D000072235:Mating Factor; D008540:Meiosis; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics*; D004718:Saccharomycetales / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000254:growth & development; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D004271:DNA, Fungal; D010455:Peptides; D000072235:Mating Factor