The role of the Saccharomyces cerevisiae Cdc7-Dbf4 complex in the replication checkpoint.

Laboratories for Biomolecular Networks, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan. oogi@fbs.osaka-u.ac.jp
The Cdc7-Dbf4 complex is a conserved serine/threonine protein kinase essential for the initiation of eukaryotic DNA replication. Although an mcm5-bob1 mutation bypasses lethality conferred by mutations in CDC7 or DBF4, the Deltacdc7 mcm5-bob1 mutant is sensitive to hydroxyurea (HU), which induces replication stress. To elucidate the reasons for HU sensitivity conferred by deletion of CDC7, we examined the role of Cdc7-Dbf4 in the replication checkpoint. We found that in Cdc7-Dbf4-deficient cells exposed to replication stress, Rad53 remains in a hypophosphorylated form, anaphase spindle is elongated, and checkpoint-specific transcription is not induced. The hypophosphorylated Rad53 exhibits a low autophosphorylation activity, and recombinant Cdc7-Dbf4 phosphorylates Rad53 in vitro. These results suggest that Cdc7-Dbf4 is required for full activation of Rad53 in response to replication stress.
Mesh Terms:
Anaphase, Blotting, Western, Cell Cycle Proteins, DNA Replication, DNA, Fungal, Gene Deletion, Gene Expression Regulation, Fungal, Hydroxyurea, Phosphorylation, Protein-Serine-Threonine Kinases, S Phase, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, beta-Galactosidase
Gene May. 15, 2008; 414(1);32-40 [PUBMED:18372119]
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