title: Distinct biological activity of threonine monophosphorylated MAPK isoforms during the stress response in fission yeast.
abstract: Mitogen-activated protein kinases (MAPKs) define a specific group of eukaryotic protein kinases which regulate a number of cellular functions by transducing extracellular signals to intracellular responses. Unlike other protein kinases, catalytic activation of MAPKs by MAPKKs depends on dual phosphorylation at two tyrosine and threonine residues within the conserved TXY motif, and this has been proposed to occur in an ordered fashion, where the initial phosphorylation on tyrosine is followed by phosphorylation at the threonine residue. However, monophosphorylated MAPKs also exist in vivo, and although threonine phosphorylated isoforms retain some catalytic activity, their functional significance remains to be further elucidated. In the fission yeast Schizosaccharomyces pombe MAPKs Sty1 and Pmk1 control multiple aspects of fission yeast life cycle, including morphogenesis, cell cycle, and cellular response to a variety of stressful situations. In this work we show that a trapping mechanism increases MAPKK binding and tyrosine phosphorylation of both Sty1 and Pmk1 when subsequent phosphorylation at threonine is hampered, indicating that a sequential and likely processive mechanism might be responsible for MAPK activation in this simple organism. Whereas threonine-monophosphorylated Sty1 showed a limited biological activity particularly at the transcriptional level, threonine-monophosphorylated Pmk1 was able to execute most of the biological functions of the dually phosphorylated kinase. Thus, threonine monophosphorylated MAPKs might display distinct functional relevance among eukaryotes.
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Vázquez
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Soto
authors.affiliation: Oxidative Stress and Cell Cycle Research Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Javier Encinar
authors.initials: JE
authors.lastname: del Dedo
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Franco
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
authors.forename: Jero
authors.initials: J
authors.lastname: Vicente
authors.affiliation: Oxidative Stress and Cell Cycle Research Group, Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Hidalgo
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
authors.forename: Mariano
authors.initials: M
authors.lastname: Gacto
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain. Electronic address: jcansado@um.es.
authors.forename: José
authors.initials: J
authors.lastname: Cansado
authors.affiliation: Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain. Electronic address: marisa@um.es.
authors.forename: Marisa
authors.initials: M
authors.lastname: Madrid
mesh_terms: D015966:Gene Expression Regulation, Fungal; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D012568:Schizosaccharomyces / Q000201:enzymology*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*; D013312:Stress, Physiological; D013912:Threonine / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029702:Schizosaccharomyces pombe Proteins; D013912:Threonine; D020928:Mitogen-Activated Protein Kinases; C516338:Pmk1 protein, S pombe; C095409:sty1 protein, S pombe
keywords: Activation; Fission yeast; MAP kinase; Phosphorylation