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Cdc7p-Dbf4p regulates mitotic exit by inhibiting Polo kinase.

Cdc7p-Dbf4p is a conserved protein kinase required for the initiation of DNA replication. The Dbf4p regulatory subunit binds Cdc7p and is essential for Cdc7p kinase activation, however, the N-terminal third of Dbf4p is dispensable for its essential replication activities. Here, we define a short N-terminal Dbf4p region that targets Cdc7p-Dbf4p kinase to Cdc5p, the single Polo kinase in budding yeast that regulates mitotic progression and cytokinesis. Dbf4p mediates an interaction with the Polo substrate-binding domain to inhibit its essential role during mitosis. Although Dbf4p does not inhibit Polo kinase activity, it nonetheless inhibits Polo-mediated activation of the mitotic exit network (MEN), presumably by altering Polo substrate targeting. In addition, although dbf4 mutants defective for interaction with Polo transit S-phase normally, they aberrantly segregate chromosomes following nuclear misorientation. Therefore, Cdc7p-Dbf4p prevents inappropriate exit from mitosis by inhibiting Polo kinase and functions in the spindle position checkpoint.

Pubmed ID: 19478884


  • Miller CT
  • Gabrielse C
  • Chen YC
  • Weinreich M


PLoS genetics

Publication Data

May 29, 2009

Associated Grants


Mesh Terms

  • Cell Cycle
  • Cell Cycle Proteins
  • Gene Expression Regulation, Fungal
  • Mitosis
  • Protein Binding
  • Protein Kinases
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins