title: Multiple modes of activation of the stress-responsive MAP kinase pathway in fission yeast.
abstract: The Schizosaccharomyces pombe wis1(+) gene is essential for cell survival under stress conditions. The MAPKK homologue Wis1 is required for activation of the MAPK homologue Spc1, and integrity of the Wis1-Spc1 pathway is required for survival in extreme conditions of heat, osmolarity, oxidation or limited nutrition. We show here that Wis4, a protein kinase of a new MAPKKK class, phosphorylates Wis1 in vitro and activates it in vivo. Win1 is also required for full activation of Wis1, and Win1 rather than Wis4 mediates the osmotic stress signal. Surprisingly, the pathway can still be activated by heat or oxidative stress independently of the phosphorylation of two conserved Wis1 residues. Evidence is presented that the Pyp1 protein tyrosine phosphatase, which dephosphorylates Spc1, is central to this alternative activation mechanism.
authors.affiliation: Institute of Cell and Molecular Biology, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK.
authors.forename: I
authors.initials: I
authors.lastname: Samejima
authors.forename: S
authors.initials: S
authors.lastname: Mackie
authors.forename: P A
authors.initials: PA
authors.lastname: Fantes
mesh_terms: D000595:Amino Acid Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics; D017124:Conserved Sequence; D004789:Enzyme Activation; D015966:Gene Expression Regulation, Fungal; D018869:Heat-Shock Response; D020930:MAP Kinase Kinase Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D018384:Oxidative Stress; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D029702:Schizosaccharomyces pombe Proteins; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C095409:sty1 protein, S pombe; D020930:MAP Kinase Kinase Kinases; C109170:win1 protein, S pombe; C109169:wis4 protein, S pombe; D020929:Mitogen-Activated Protein Kinase Kinases; C072068:wis1 protein, S pombe