Expression of the BAR1 gene in Saccharomyces cerevisiae: induction by the alpha mating pheromone of an activity associated with a secreted protein.
We have demonstrated and partially characterized the genetic control and pheromonal regulation of a soluble activity, produced only by mating-type a cells, that inhibits the action of the alpha mating pheromone, alpha-factor, on mating-type a cells. This activity was found to be associated with a heat-stable protein and to be secreted by MATa BAR1, mat alpha 2 BAR1, and mat alpha 1 mat alpha 2 BAR1 strains, but not by MAT alpha BAR1, MATa/MAT alpha BAR1, mat alpha 1 BAR1, or MATa barl strains, demonstrating that it is under the control of both the MAT alpha 2 and the BAR1 genes. Secretion of this activity was also found to be stimulated to as much as five times the basal level by exposure of the cells to alpha-factor. This stimulation was maximal after 6 h at a pheromone concentration of approximately 2 U/ml. An assay for this activity was developed by using a refined, quantitative assay for alpha-factor. The pheromone activity of samples added to wells in an agar plate was related to the size of the halo of growth inhibition produced in a lawn of mutant cells that are abnormally sensitive. The alpha-factor-inhibiting activity was related to a reduction of the halo size when active samples were added to the lawn. Although the assay for alpha-factor was found to be relatively insensitive to pH over a range of several units, the alpha-factor-inhibiting activity displayed a sharp pH optimum at approximately 6.5. The properties of this activity have important implications concerning the role of the BAR1 gene product in recovery of mating-type a cells from cell division arrest by alpha-factor.
D000818:Animals; D005656:Fungal Proteins / Q000235:genetics*; D005796:Genes; D005838:Genotype; D007700:Kinetics; D000072235:Mating Factor; D009154:Mutation; D010455:Peptides / Q000502:physiology*; D010675:Pheromones / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013045:Species Specificity
D005656:Fungal Proteins; D010455:Peptides; D010675:Pheromones; D000072235:Mating Factor