Spm1, a stress-activated MAP kinase that regulates morphogenesis in S.pombe.
A gene encoding a novel MAP kinase family member, Spm1, was isolated from the fission yeast Schizosaccharomyces pombe. Overproduction of Spm1 inhibits proliferation. Disruption of the spm1+ gene interferes with cell separation and morphogenesis. Under conditions of nutrient limitation, hypertonic stress or elevated temperature, spm1 delta cells grow as short branched filaments in which the cell walls and septa are thickened, suggesting defects in polarized growth and cell wall remodeling. At high osmolarity, spm1 delta cells fail to form colonies. The Spm1 protein is tyrosine phosphorylated and activated in response to osmotic and heat stress, consistent with a role for Spm1 in adaptation to these conditions. Two other S.pombe MAP kinases are known, Spk1, required for sexual differentiation and sporulation, and Spc1/Sty1/Phh1, which is activated in hypertonic conditions. However, the distinctive features of the spm1 delta mutant phenotype and direct biochemical assays suggest that Spm1 does not lie on other known MAP kinase pathways. Our results demonstrate the existence of a new MAP kinase pathway that regulates cell wall remodeling and cytokinesis in response to environmental stresses.
Zaitsevskaya-Carter
T
T
Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
Cooper
J A
JA
D000595:Amino Acid Sequence; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D064447:Checkpoint Kinase 2; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008854:Microscopy, Electron; D020929:Mitogen-Activated Protein Kinase Kinases; D008969:Molecular Sequence Data; D009154:Mutation; D009994:Osmolar Concentration; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D018631:ras Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; C085569:GAL83 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C067022:RAD53 protein, S cerevisiae; D020929:Mitogen-Activated Protein Kinase Kinases; C072068:wis1 protein, S pombe; D018631:ras Proteins