RAP1 protein activates and silences transcription of mating-type genes in yeast.
RAP1 is a sequence-specific DNA-binding protein essential for cell growth. The occurrence of RAP1-binding sites in many promoter regions, the mating-type gene silencer elements, and telomeres suggests that RAP1 has multiple functions in the cell. To assess its role in transcription, temperature-sensitive mutations in RAP1 were generated. Analysis of rap1ts strains provides evidence that RAP1 functions in both transcriptional activation and silencing of mating-type genes. Several observations indicate that rap1ts strains are defective in the expression of MAT alpha, whose upstream activation sequence (UAS) contains a RAP1-binding site. At nonpermissive temperatures, decreases in MAT alpha steady-state transcript levels can be detected in MAT alpha rap1ts strains. Furthermore, these strains are deficient in alpha-pheromone production and simultaneously express at least two alpha-specific genes. These phenotypes can be reversed by replacing the RAP1-binding site at MAT alpha with a binding site for the GAL4 transcriptional activator. Certain rap1ts alleles have an opposite effect on the silent mating-type locus HMR, which becomes partially derepressed at nonpermissive temperatures.
Kurtz
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Department of Microbiology, College of Physicians & Surgeons, Columbia University, New York, New York 10032.
Shore
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D000483:Alleles; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D005838:Genotype; D007700:Kinetics; D000072235:Mating Factor; D010455:Peptides / Q000235:genetics*; D010675:Pheromones / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D010455:Peptides; D010675:Pheromones; D014157:Transcription Factors; D000072235:Mating Factor