Cdc7-Dbf4 phosphorylates MCM proteins via a docking site-mediated mechanism to promote S phase progression

Mol Cell. 2006 Oct 6;24(1):101-13. doi: 10.1016/j.molcel.2006.07.033.

Abstract

Origins of DNA replication are licensed in G1 by recruiting the minichromosome maintenance (MCM) proteins to form a prereplicative complex (pre-RC). Prior to initiation of DNA synthesis from each origin, a preinitiation complex (pre-IC) containing Cdc45 and other proteins is formed. We report that Cdc7-Dbf4 protein kinase (DDK) promotes assembly of a stable Cdc45-MCM complex exclusively on chromatin in S phase. In this complex, Mcm4 is hyperphosphorylated. Studies in vitro using purified DDK and Mcm4 demonstrate that hyperphosphorylation occurs at the Mcm4 N terminus. However, the DDK substrate specificity is conferred by an adjacent DDK-docking domain (DDD), sufficient for facilitating efficient phosphorylation of artificial phosphoacceptors in cis. Genetic evidence suggests that phosphorylation of Mcm4 by DDK is important for timely S phase progression and for cell viability upon overproduction of Cdc45. We suggest that DDK docks on and phosphorylates MCM proteins at licensed origins to promote proper assembly of pre-IC.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Apoenzymes / metabolism
  • Binding Sites
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism*
  • Cell Cycle Proteins / physiology
  • Chromatin / metabolism
  • Conserved Sequence
  • DNA Replication
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology
  • Minichromosome Maintenance Complex Component 4
  • Models, Biological
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / physiology
  • Phosphorylation
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / metabolism*
  • Protein-Serine-Threonine Kinases / physiology
  • S Phase / physiology*
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology
  • Sequence Alignment

Substances

  • Apoenzymes
  • CDC45 protein, S cerevisiae
  • Cell Cycle Proteins
  • Chromatin
  • DNA-Binding Proteins
  • Dbf4 protein, S cerevisiae
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • CDC7 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases
  • MCM4 protein, S cerevisiae
  • Minichromosome Maintenance Complex Component 4