title: Coordination of the mating and cell integrity mitogen-activated protein kinase pathways in Saccharomyces cerevisiae.
abstract: Mating pheromone stimulates a mitogen-activated protein (MAP) kinase activation pathway in Saccharomyces cerevisiae that induces cells to differentiate and form projections oriented toward the gradient of pheromone secreted by a mating partner. The polarized growth of mating projections involves new cell wall synthesis, a process that relies on activation of the cell integrity MAP kinase, Mpk1. In this report, we show that Mpk1 activation during pheromone induction requires the transcriptional output of the mating pathway and protein synthesis. Consequently, Mpk1 activation occurs subsequent to the activation of the mating pathway MAP kinase cascade. Additionally, Spa2 and Bni1, a formin family member, are two coil-coil-related proteins that are involved in the timing and other aspects of mating projection formation. Both proteins also affect the timing and extent of Mpk1 activation. This correlation suggests that projection formation comprises part of the pheromone-induced signal that coordinates Mpk1 activation with mating differentiation. Stimulation of Mpk1 activity occurs through the cell integrity phosphorylation cascade and depends on Pkc1 and the redundant MAP/Erk kinases (MEKs), Mkk1 and Mkk2. Surprisingly, Mpk1 activation by pheromone was only partially impaired in cells lacking the MEK kinase Bck1. This Bck1-independent mechanism reveals the existence of an alternative activator of Mkk1/Mkk2 in some strain backgrounds that at least functions under pheromone-induced conditions.
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, 27599-7260, USA.
authors.forename: B M
authors.initials: BM
authors.lastname: Buehrer
authors.forename: B
authors.initials: B
authors.lastname: Errede
mesh_terms: D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D003598:Cytoskeletal Proteins; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D008840:Microfilament Proteins; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D008954:Models, Biological; D010675:Pheromones / Q000494:pharmacology*; D014176:Protein Biosynthesis; D011493:Protein Kinase C; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012098:Reproduction / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: C105191:Bni1 protein, S cerevisiae; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; D008840:Microfilament Proteins; D010675:Pheromones; C065889:SPA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C097993:Pkc1 protein, Trichoderma reesei; D011505:Protein-Tyrosine Kinases; C072075:BCK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases