Increased mobility of double-strand breaks requires Mec1, Rad9 and the homologous recombination machinery

Nat Cell Biol. 2012 Apr 8;14(5):502-9. doi: 10.1038/ncb2465.


Chromatin mobility is thought to facilitate homology search during homologous recombination and to shift damage either towards or away from specialized repair compartments. However, unconstrained mobility of double-strand breaks could also promote deleterious chromosomal translocations. Here we use live time-lapse fluorescence microscopy to track the mobility of damaged DNA in budding yeast. We found that a Rad52-YFP focus formed at an irreparable double-strand break moves in a larger subnuclear volume than the undamaged locus. In contrast, Rad52-YFP bound at damage arising from a protein-DNA adduct shows no increase in movement. Mutant analysis shows that enhanced double-strand-break mobility requires Rad51, the ATPase activity of Rad54, the ATR homologue Mec1 and the DNA-damage-response mediator Rad9. Consistent with a role for movement in the homology-search step of homologous recombination, we show that recombination intermediates take longer to form in cells lacking Rad9.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / physiology*
  • Chromatin / metabolism
  • DNA Damage*
  • Intracellular Signaling Peptides and Proteins / physiology*
  • Microscopy, Fluorescence
  • Protein-Serine-Threonine Kinases / physiology*
  • Recombination, Genetic*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / physiology*


  • Cell Cycle Proteins
  • Chromatin
  • Intracellular Signaling Peptides and Proteins
  • Saccharomyces cerevisiae Proteins
  • rad9 protein
  • MEC1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases