Fission yeast mitogen-activated protein kinase Sty1 interacts with translation factors.
Signaling by stress-activated mitogen-activated protein kinase (MAPK) pathways influences translation efficiency in mammalian cells and budding yeast. We have investigated the stress-activated MAPK from fission yeast, Sty1, and its downstream protein kinase, Mkp1/Srk1, for physically associated proteins using tandem affinity purification tagging. We find Sty1, but not Mkp1, to bind to the translation elongation factor eukaryotic elongation factor 2 (eEF2) and the translation initiation factor eukaryotic initiation factor 3a (eIF3a). The Sty1-eIF3a interaction is weakened under oxidative or hyperosmotic stress, whereas the Sty1-eEF2 interaction is stable. Nitrogen deprivation causes a transient strengthening of both the Sty1-eEF2 and the Sty1-Mkp1 interactions, overlapping with the time of maximal Sty1 activation. Analysis of polysome profiles from cells under oxidative stress, or after hyperosmotic shock or nitrogen deprivation, shows that translation in sty1 mutant cells recovers considerably less efficiently than that in the wild type. Cells lacking the Sty1-regulated transcription factor Atf1 are deficient in maintaining and recovering translational activity after hyperosmotic shock but not during oxidative stress or nitrogen starvation. In cells lacking Sty1, eIF3a levels are decreased, and phosphorylation of eIF3a is reduced. Taken together, our data point to a central role in translational adaptation for the stress-activated MAPK pathway in fission yeast similar to that in other investigated eukaryotes, with the exception that fission yeast MAPK-activated protein kinases seem not to be directly involved in this process.
Department of Cell and Molecular Biology, Lundberg Laboratory, Göteborg University, PO Box 462 SE-405 30 Göteborg, Sweden.
Eva
E
Asp
Daniel
D
Nilsson
Per
P
Sunnerhagen
D002846:Chromatography, Affinity; D015180:Electrophoresis, Gel, Two-Dimensional; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism*; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000172:deficiency; D009997:Osmotic Pressure; D018384:Oxidative Stress; D010766:Phosphorylation; D011132:Polyribosomes; D014176:Protein Biosynthesis; D012568:Schizosaccharomyces / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D015852:Eukaryotic Initiation Factor-2; D039621:Eukaryotic Initiation Factor-3; D005656:Fungal Proteins; D029702:Schizosaccharomyces pombe Proteins; D020928:Mitogen-Activated Protein Kinases; C095409:sty1 protein, S pombe; D009584:Nitrogen