Identification of asymmetrically localized determinant, Ash1p, required for lineage-specific transcription of the yeast HO gene.
S. cerevisiae cells exhibit asymmetric determination of cell fate. Cell division yields a mother cell, which is competent to transcribe the HO gene and switch mating type, and a daughter cell, which is not. We have isolated a mutant in which daughters transcribe HO and switch mating type. This mutation defines the ASH1 gene (asymmetric synthesis of HO). Deletion and overexpression of ASH1 cause reciprocal cell fate transformations: im ash1delta strains, daughters switch mating type as efficiently as mothers. Conversely, overexpression of ASH1 inhibits switching in mother cells. Ash1p has a zinc finger motif related to those of GATA transcriptional regulators. Ash1p is localized to the daughter nucleus in cells that have undergone nuclear division. Thus, Ash1p is a cell fate determinant that is asymmetrically localized to the daughter nucleus where it inhibits HO transcription.
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Department of Biochemistry and Biophysics, University of California, San Francisco, 94143-0448 USA.
Herskowitz
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D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D015252:Deoxyribonucleases, Type II Site-Specific / Q000096:biosynthesis* / Q000235:genetics; D005020:Ethyl Methanesulfonate; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D005838:Genotype; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009153:Mutagens; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
C098733:ASH1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D009153:Mutagens; D011994:Recombinant Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D005020:Ethyl Methanesulfonate; C530845:HO protein, S cerevisiae; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific