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Heat stress activates fission yeast Spc1/StyI MAPK by a MEKK-independent mechanism

Academic Article
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Overview

authors

  • Shiozaki, K.
  • Shiozaki, M.
  • Russell, Paul

publication date

  • June 1998

journal

  • Molecular Biology of the Cell  Journal

abstract

  • Fission yeast Spc1/StyI MAPK is activated by many environmental insults including high osmolarity, oxidative stress, and heat shock. Spc1/StyI is activated by Wis1, a MAPK kinase (MEK), which is itself activated by Wik1/Wak1/Wis4, a MEK kinase (MEKK). Spc1/StyI is inactivated by the tyrosine phosphatases Pyp1 and Pyp2. Inhibition of Pyp1 was recently reported to play a crucial role in the oxidative stress and heat shock responses. These conclusions were based on three findings: 1) osmotic, oxidative, and heat stresses activate Spc1/StyI in wis4 cells; 2) oxidative stress and heat shock activate Spc1/StyI in cells that express Wis1AA, in which MEKK consensus phosphorylation sites were replaced with alanine; and 3) Spc1/StyI is maximally activated in Deltapyp1 cells. Contrary to these findings, we report: 1) Spc1/StyI activation by osmotic stress is greatly reduced in wis4 cells; 2) wis1-AA and Deltawis1 cells have identical phenotypes; and 3) all forms of stress activate Spc1/StyI in Deltapyp1 cells. We also report that heat shock, but not osmotic or oxidative stress, activate Spc1 in wis1-DD cells, which express Wis1 protein that has the MEKK consensus phosphorylation sites replaced with aspartic acid. Thus osmotic and oxidative stress activate Spc1/StyI by a MEKK-dependent process, whereas heat shock activates Spc1/StyI by a novel mechanism that does not require MEKK activation or Pyp1 inhibition.

subject areas

  • Binding Sites
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Cell Cycle Proteins
  • Conserved Sequence
  • Enzyme Activation
  • Heat-Shock Response
  • MAP Kinase Kinase Kinases
  • Mitogen-Activated Protein Kinases
  • Osmotic Pressure
  • Oxidative Stress
  • Phosphorylation
  • Protein Tyrosine Phosphatases
  • Protein-Serine-Threonine Kinases
  • Schizosaccharomyces
  • Schizosaccharomyces pombe Proteins
  • Serine
  • Signal Transduction
  • Threonine
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Identity

PubMed Central ID

  • PMC25354

International Standard Serial Number (ISSN)

  • 1059-1524

Digital Object Identifier (DOI)

  • 10.1091/mbc.9.6.1339

PubMed ID

  • 9614178
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Additional Document Info

start page

  • 1339

end page

  • 1349

volume

  • 9

issue

  • 6

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