MAP kinases with distinct inhibitory functions impart signaling specificity during yeast differentiation.
Filamentous invasive growth of S. cerevisiae requires multiple elements of the mitogen-activated protein kinase (MAPK) signaling cascade that are also components of the mating pheromone response pathway. Here we show that, despite sharing several constituents, the two pathways use different MAP kinases. The Fus3 MAPK regulates mating, whereas the Kss1 MAPK regulates filamentation and invasion. Remarkably, in addition to their kinase-dependent activation functions, Kss1 and Fus3 each have a distinct kinase-independent inhibitory function. Kss1 inhibits the filamentation pathway by interacting with its target transcription factor Ste12. Fus3 has a different inhibitory activity that prevents the inappropriate activation of invasion by the pheromone response pathway. In the absence of Fus3, there is erroneous crosstalk in which mating pheromone now activates filamentation-specific gene expression using the Kss1 MAPK.
Madhani
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HD
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
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Fink
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D000596:Amino Acids / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal / Q000502:physiology; D006238:Haploidy; D000072235:Mating Factor; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009154:Mutation; D010455:Peptides / Q000502:physiology; D010675:Pheromones / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism
D000596:Amino Acids; D005656:Fungal Proteins; D010455:Peptides; D010675:Pheromones; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000072235:Mating Factor; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C075580:FUS3 protein, S cerevisiae; C541984:KSS1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases