The S-phase checkpoint: targeting the replication fork

Biol Cell. 2009 Aug 19;101(11):617-27. doi: 10.1042/BC20090053.


The S-phase checkpoint is a surveillance mechanism, mediated by the protein kinases Mec1 and Rad53 in the budding yeast Saccharomyces cerevisiae (ATR and Chk2 in human cells, respectively) that responds to DNA damage and replication perturbations by co-ordinating a global cellular response necessary to maintain genome integrity. A key aspect of this response is the stabilization of DNA replication forks, which is critical for cell survival. A defective checkpoint causes irreversible replication-fork collapse and leads to genomic instability, a hallmark of cancer cells. Although the precise mechanisms by which Mec1/Rad53 maintain functional replication forks are currently unclear, our knowledge about this checkpoint function has significantly increased during the last years. Focusing mainly on the advances obtained in S. cerevisiae, the present review will summarize our understanding of how the S-phase checkpoint preserves the integrity of DNA replication forks and discuss the most recent findings on this topic.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Checkpoint Kinase 2
  • DNA Replication*
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • S Phase*
  • Saccharomyces cerevisiae / cytology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism


  • Cell Cycle Proteins
  • Intracellular Signaling Peptides and Proteins
  • Saccharomyces cerevisiae Proteins
  • Checkpoint Kinase 2
  • MEC1 protein, S cerevisiae
  • Protein Serine-Threonine Kinases
  • RAD53 protein, S cerevisiae