A ste12 allele having a differential effect on a versus alpha cells.
The transcriptional activator Ste12p is a key component of the yeast pheromone response pathway: phosphorylated as a consequence of signal transduction, it activates transcription of genes that promote mating and the subsequent fusion of the two cell types a and alpha. Activation by Ste12p requires three types of protein-protein interaction between DNA-binding activator proteins: (1) Ste12p by itself can induce non-cell-type-specific genes involved in mating; (2) cooperation of the transactivator Mcm1p with Ste12p induces a-specific genes; and (3) formation of a complex of the activator proteins Mcm1p and alpha 1 (a transcriptional activator of alpha-specific genes) with Ste12p is believed to induce alpha-specific genes. We isolated and characterized a partially functional ste12 allele (ste12-T50), that is defective only in the activation of alpha-specific genes. ste12-T50 was isolated as a second-site mutation conferring the a mating phenotype on mat alpha 2 mutant cells. In mat alpha 2 cells, where due to the lack of repressor, alpha 2, both sets of cell-type-specific genes are expressed, ste12-T50 apparently tips the balance in favor of a-specific gene expression. Thus, mat alpha 2 ste12-T50 cells mate like a cells. Additional ste12 mutants that confer the a mating phenotype on mat alpha 2 cells have also been isolated.
La Roche
S D
SD
Laboratory of Eukaryotic Gene Expression, NCI-Frederick Cancer Research and Development Center, ABL-Basic Research Program, Maryland 21702-1201.
Shafer
B K
BK
Strathern
J N
JN
D000483:Alleles; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D026341:Minichromosome Maintenance 1 Protein; D010641:Phenotype; D017354:Point Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D012724:Sex Attractants / Q000096:biosynthesis / Q000235:genetics; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D026341:Minichromosome Maintenance 1 Protein; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012724:Sex Attractants; D015534:Trans-Activators; D014157:Transcription Factors