Replisome stability at defective DNA replication forks is independent of S phase checkpoint kinases

Mol Cell. 2012 Mar 9;45(5):696-704. doi: 10.1016/j.molcel.2012.01.007. Epub 2012 Feb 9.


The S phase checkpoint pathway preserves genome stability by protecting defective DNA replication forks, but the underlying mechanisms are still understood poorly. Previous work with budding yeast suggested that the checkpoint kinases Mec1 and Rad53 might prevent collapse of the replisome when nucleotide concentrations are limiting, thereby allowing the subsequent resumption of DNA synthesis. Here we describe a direct analysis of replisome stability in budding yeast cells lacking checkpoint kinases, together with a high-resolution view of replisome progression across the genome. Surprisingly, we find that the replisome is stably associated with DNA replication forks following replication stress in the absence of Mec1 or Rad53. A component of the replicative DNA helicase is phosphorylated within the replisome in a Mec1-dependent manner upon replication stress, and our data indicate that checkpoint kinases control replisome function rather than stability, as part of a multifaceted response that allows cells to survive defects in chromosome replication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / genetics
  • Cell Cycle / physiology
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / physiology*
  • Checkpoint Kinase 2
  • DNA Replication / physiology*
  • Genomic Instability
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / physiology*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / physiology*
  • S Phase Cell Cycle Checkpoints*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / physiology*
  • Stress, Physiological


  • 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