Mating in Saccharomyces cerevisiae: the role of the pheromone signal transduction pathway in the chemotropic response to pheromone.
The mating process in yeast has two distinct aspects. One is the induction and activation of proteins required for cell fusion in response to a pheromone signal; the other is chemotropism, i.e., detection of a pheromone gradient and construction of a fusion site available to the signaling cell. To determine whether components of the signal transduction pathway necessary for transcriptional activation also play a role in chemotropism, we examined strains with null mutations in components of the signal transduction pathway for diploid formation, prezygote formation and the chemotropic process of mating partner discrimination when transcription was induced downstream of the mutation. Cells mutant for components of the mitogen-activated protein (MAP) kinase cascade (ste5, ste20, ste11, ste7 or fus3 kss1) formed diploids at a frequency 1% that of the wild-type control, but formed prezygotes as efficiently as the wild-type control and showed good mating partner discrimination, suggesting that the MAP kinase cascade is not essential for chemotropism. In contrast, cells mutant for the receptor (ste2) or the beta or gamma subunit (ste4 and ste18) of the G protein were extremely defective in both diploid and prezygote formation and discriminated poorly between signaling and nonsignaling mating partners, implying that these components are important for chemotropism.
Schrick
K
K
Department of Genetics, University of Washington, Seattle 98195-7360, USA.
Garvik
B
B
Hartwell
L H
LH
D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology; D002633:Chemotaxis / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D044385:GTP-Binding Protein alpha Subunits; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology; D015870:Gene Expression; D005800:Genes, Fungal / Q000502:physiology; D020962:Heterotrimeric GTP-Binding Proteins; D008074:Lipoproteins / Q000235:genetics / Q000502:physiology; D000072235:Mating Factor; D009154:Mutation; D010455:Peptides / Q000235:genetics / Q000502:physiology; D010675:Pheromones / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
D005656:Fungal Proteins; D044385:GTP-Binding Protein alpha Subunits; D008074:Lipoproteins; C095063:MFA2 protein, S cerevisiae; D010455:Peptides; D010675:Pheromones; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000072235:Mating Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; C084293:GPA1 protein, S cerevisiae; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins