SMK1, a developmentally regulated MAP kinase, is required for spore wall assembly in Saccharomyces cerevisiae.
Mitogen-activated protein (MAP) kinases comprise a family of conserved, eukaryotic enzymes that mediate responses to a wide variety of extracellular stimuli. In yeast, different signal transduction pathways utilize distinct MAP kinase family members. We have identified a new yeast MAP kinase gene (named SMK1) that is required for the completion of sporulation. Molecular and cytologic markers indicate that meiotic development proceeds normally in homozygous smk1-delta 1 diploids through meiosis II. However, light and electron microscopy show that smk1 asci are defective in organizing spore wall assembly. Consistent with a defect in spore wall assembly, smk1-delta 1 mutant asci display enhanced sensitivities to enzymatic digestion, heat shock, and exposure to ether. SMK1 mRNA, which is not detectable in vegetative cells, is derepressed at least 200-fold just prior to prospore enclosure. We propose that the SMK1 MAP kinase participates in a developmentally regulated signal transduction pathway that coordinates cytodifferentiation events with the transcriptional program.
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
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L
Krisak
R
R
Strich
R S
RS
Winters
J P
JP
Hall
M J
MJ
Mallory
D
D
Kreitzer
R S
RS
Tuan
E
E
Winter
D000595:Amino Acid Sequence; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008540:Meiosis / Q000235:genetics; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D013172:Spores, Fungal / Q000201:enzymology / Q000235:genetics / Q000254:growth & development
D017931:DNA Primers; D004271:DNA, Fungal; D017871:Calcium-Calmodulin-Dependent Protein Kinases