Protein phosphatase 1 recruitment by Rif1 regulates DNA replication origin firing by counteracting DDK activity

Cell Rep. 2014 Apr 10;7(1):53-61. doi: 10.1016/j.celrep.2014.02.019. Epub 2014 Mar 20.

Abstract

The firing of eukaryotic origins of DNA replication requires CDK and DDK kinase activities. DDK, in particular, is involved in setting the temporal program of origin activation, a conserved feature of eukaryotes. Rif1, originally identified as a telomeric protein, was recently implicated in specifying replication timing in yeast and mammals. We show that this function of Rif1 depends on its interaction with PP1 phosphatases. Mutations of two PP1 docking motifs in Rif1 lead to early replication of telomeres in budding yeast and misregulation of origin firing in fission yeast. Several lines of evidence indicate that Rif1/PP1 counteract DDK activity on the replicative MCM helicase. Our data suggest that the PP1/Rif1 interaction is downregulated by the phosphorylation of Rif1, most likely by CDK/DDK. These findings elucidate the mechanism of action of Rif1 in the control of DNA replication and demonstrate a role of PP1 phosphatases in the regulation of origin firing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle Proteins / metabolism*
  • DNA Replication / physiology*
  • Phosphorylation
  • Protein Phosphatase 1 / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Replication Origin / physiology*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Schizosaccharomyces / metabolism
  • Telomere / metabolism
  • Telomere-Binding Proteins / genetics
  • Telomere-Binding Proteins / metabolism*

Substances

  • Cell Cycle Proteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Telomere-Binding Proteins
  • RIF1 protein, S cerevisiae
  • CDC7 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • Protein Phosphatase 1