Yeast Spindle Pole Body Duplication Gene MPS1 Encodes an Essential Dual Specificity Protein Kinase

EMBO J. 1995 Apr 18;14(8):1655-63.

Abstract

The MPS1 gene has been previously identified by a mutant allele that shows defects in spindle pole body (SPB) duplication and cell cycle control. The SPB is the centrosome-equivalent organelle in the yeast Saccharomyces cerevisiae, and it nucleates all the microtubules in the cell. We report the isolation of the MPS1 gene, which encodes an essential protein kinase homolog. The MPS1 open reading frame has been fused to those that encode the LexA protein or the GST protein and both of these constructs function in yeast. The fusion proteins have been affinity-purified from yeast extracts and the GST chimeric protein has been found to be a phosphoprotein. Both proteins have been used to demonstrate intrinsic in vitro protein kinase activity of Mps1p against exogenous substrates and itself (autophosphorylation). A mutation predicted to abolish kinase function not only eliminates in vitro protein kinase activity, but also behaves like a null mutation in vivo, suggesting that kinase activity contributes to the essential function of the protein. Phosphoamino acid analysis of substrates phosphorylated by Mps1p indicates that this kinase can phosphorylate serine, threonine and tyrosine residues, identifying Mps1p as a dual specificity protein kinase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Centrosome / enzymology*
  • Genes, Fungal / genetics*
  • Genes, Lethal / genetics
  • Genomic Library
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases
  • Protein-Tyrosine Kinases
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Serine / metabolism
  • Substrate Specificity
  • Threonine / metabolism
  • Tyrosine / metabolism

Substances

  • Saccharomyces cerevisiae Proteins
  • Threonine
  • Tyrosine
  • Serine
  • Protein Kinases
  • Protein-Tyrosine Kinases
  • Protein-Serine-Threonine Kinases
  • MPS1 protein, S cerevisiae