Evidence for a Cdc6p-independent mitotic resetting event involving DNA polymerase alpha

EMBO J. 1998 Jul 15;17(14):4139-46. doi: 10.1093/emboj/17.14.4139.

Abstract

Eukaryotic DNA replication is limited to once per cell cycle because cyclin-dependent kinases (cdks), which are required to fire origins, also prevent re-replication. Components of the replication apparatus, therefore, are 'reset' by cdk inactivation at the end of mitosis. In budding yeast, assembly of Cdc6p-dependent pre-replicative complexes (pre-RCs) at origins can only occur during G1 because it is blocked by cdk1 (Cdc28) together with B cyclins (Clbs). Here we describe a second, separate process which is also blocked by Cdc28/Clb kinase and, therefore, can only occur during G1; the recruitment of DNA polymerase alpha-primase (pol alpha) to chromatin. The recruitment of pol alpha to chromatin during G1 is independent of pre-RC formation since it can occur in the absence of Cdc6 protein. Paradoxically, overproduction of Cdc6p can drive both dephosphorylation and chromatin association of pol alpha. Overproduction of a mutant in which the N-terminus of Cdc6 has been deleted is unable to drive pol alpha chromatin binding. Since this mutant is still competent for pre-RC formation and DNA replication, we suggest that Cdc6p overproduction resets pol alpha chromatin binding by a mechanism which is independent of that used in pre-RC assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CDC28 Protein Kinase, S cerevisiae / metabolism*
  • Cell Cycle Proteins / physiology*
  • Chromatin / metabolism
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • DNA Polymerase I / metabolism*
  • DNA Primase / metabolism
  • DNA Replication / physiology*
  • Fungal Proteins / genetics
  • Fungal Proteins / physiology
  • G1 Phase / physiology
  • Mitosis / physiology*
  • Phosphorylation
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*

Substances

  • CDC6 protein, S cerevisiae
  • Cell Cycle Proteins
  • Chromatin
  • Cyclin-Dependent Kinase Inhibitor Proteins
  • Fungal Proteins
  • Recombinant Fusion Proteins
  • SIC1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • CDC28 Protein Kinase, S cerevisiae
  • DNA Primase
  • DNA Polymerase I

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