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Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM

Shin-Ichiro Hiraga1, Gina M Alvino, Fujung Chang

  • 1Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom;

Genes & Development
|February 18, 2014
PubMed

Insights

Budding yeast Rif1 protein controls DNA replication by opposing Dbf4-dependent kinase (DDK) activity. Rif1 directs Protein Phosphatase 1 (PP1) to dephosphorylate the MCM complex, ensuring proper replication timing.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Eukaryotic DNA replication initiation depends on MCM complex phosphorylation by Dbf4-dependent kinase (DDK).
  • Rif1 (Rap1-interacting factor 1) is implicated in regulating DNA replication in various yeast and mammalian species.

Purpose of the Study:

  • To investigate the role of budding yeast Rif1 in controlling genome-wide DNA replication.
  • To elucidate the mechanism by which Rif1 opposes DDK function during replication.

Main Methods:

  • Genetic analysis of cdc7-1 mutant strains with and without RIF1 deletion.
  • Biochemical assays to confirm Rif1 interaction with Protein Phosphatase 1 (PP1).
  • Phosphorylation analysis of the MCM complex component Mcm4.

Main Results:

  • Deletion of RIF1 partially rescues the cdc7-1 mutant phenotype by increasing Mcm4 phosphorylation.
  • Rif1 directly interacts with PP1, mediating dephosphorylation of the MCM complex.
  • Rif1's repressive effect on replication is dependent on its PP1 interaction motifs and is itself regulated by DDK phosphorylation.

Conclusions:

  • Rif1 acts as a novel PP1 substrate targeting subunit that counteracts DDK-mediated MCM phosphorylation.
  • Rif1-mediated replication control via PP1 is likely a conserved mechanism across eukaryotes.
Keywords:
DNA replicationPP1protein kinaseprotein phosphataseprotein phosphorylation

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