Control of yeast alpha-specific genes: evidence for two blocks to expression in MATa/MAT alpha diploids.
In yeast alpha cells, the product encoded by the MAT alpha 1 gene of the mating-type locus is required for transcription of at least two genes, STE3 and MF alpha 1. To learn whether the lack of the MAT alpha 1 product in a and a/alpha cells is sufficient to explain the failure to express STE3 and MF alpha 1 in these cells, we have provided MAT alpha 1 product via a hybrid gene that circumvents the normal regulation of the MAT alpha 1 gene. We find by RNA blot analysis that provision of MAT alpha 1 protein permits production of STE3 and MF alpha 1 mRNA in a cells but not in a/alpha cells. These data suggest the existence of an additional regulatory mechanism that prevents expression of alpha-specific genes in a/alpha cells, even when MAT alpha 1 product is present. This regulatory mechanism appears to control expression of STE3 and MF alpha 1 at the transcriptional level rather than at the posttranscriptional level, because we show that MF alpha 1 mRNA supplied from a constitutive promoter is translated and processed in a/alpha cells to yield functional alpha-factor pheromone. This result shows further that a/alpha cells possess all the machinery necessary for pheromone maturation, even though these cells do not normally carry out these reactions.
D000818:Animals; D004274:DNA, Recombinant; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D005809:Genes, Regulator; D000072235:Mating Factor; D010455:Peptides / Q000235:genetics; D010675:Pheromones / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014158:Transcription, Genetic
D004274:DNA, Recombinant; D005656:Fungal Proteins; D010455:Peptides; D010675:Pheromones; D012331:RNA, Fungal; D012333:RNA, Messenger; D000072235:Mating Factor