Histone methyltransferase Dot1 and Rad9 inhibit single-stranded DNA accumulation at DSBs and uncapped telomeres

EMBO J. 2008 May 21;27(10):1502-12. doi: 10.1038/emboj.2008.81. Epub 2008 Apr 17.

Abstract

Cells respond to DNA double-strand breaks (DSBs) and uncapped telomeres by recruiting checkpoint and repair factors to the site of lesions. Single-stranded DNA (ssDNA) is an important intermediate in the repair of DSBs and is produced also at uncapped telomeres. Here, we provide evidence that binding of the checkpoint protein Rad9, through its Tudor domain, to methylated histone H3-K79 inhibits resection at DSBs and uncapped telomeres. Loss of DOT1 or mutations in RAD9 influence a Rad50-dependent nuclease, leading to more rapid accumulation of ssDNA, and faster activation of the critical checkpoint kinase, Mec1. Moreover, deletion of RAD9 or DOT1 partially bypasses the requirement for CDK1 in DSB resection. Interestingly, Dot1 contributes to checkpoint activation in response to low levels of telomere uncapping but is not essential with high levels of uncapping. We suggest that both Rad9 and histone H3 methylation allow transmission of the damage signal to checkpoint kinases, and keep resection of damaged DNA under control influencing, both positively and negatively, checkpoint cascades and contributing to a tightly controlled response to DNA damage.

Publication types

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

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • DNA Breaks, Double-Stranded*
  • DNA, Single-Stranded / antagonists & inhibitors*
  • Enzyme Activation
  • Gene Deletion
  • Histone-Lysine N-Methyltransferase
  • Histones / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Methylation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Telomere / metabolism*

Substances

  • Cell Cycle Proteins
  • DNA, Single-Stranded
  • Histones
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • Saccharomyces cerevisiae Proteins
  • rad9 protein
  • Dot1 protein, S cerevisiae
  • Histone-Lysine N-Methyltransferase
  • MEC1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases