Distribution and dynamics of chromatin modification induced by a defined DNA double-strand break

Curr Biol. 2004 Oct 5;14(19):1703-11. doi: 10.1016/j.cub.2004.09.047.


Background: In response to DNA double-strand breaks (DSBs), eukaryotic cells rapidly phosphorylate histone H2A isoform H2AX at a C-terminal serine (to form gamma-H2AX) and accumulate repair proteins at or near DSBs. To date, these events have been defined primarily at the resolution of light microscopes, and the relationship between gamma-H2AX formation and repair protein recruitment remains to be defined.

Results: We report here the first molecular-level characterization of regional chromatin changes that accompany a DSB formed by the HO endonuclease in Saccharomyces cerevisiae. Break induction provoked rapid gamma-H2AX formation and equally rapid recruitment of the Mre11 repair protein. gamma-H2AX formation was efficiently promoted by both Tel1p and Mec1p, the yeast ATM and ATR homologs; in G1-arrested cells, most gamma-H2AX formation was dependent on Tel1 and Mre11. gamma-H2AX formed in a large (ca. 50 kb) region surrounding the DSB. Remarkably, very little gamma-H2AX could be detected in chromatin within 1-2 kb of the break. In contrast, this region contains almost all the Mre11p and other repair proteins that bind as a result of the break.

Conclusions: Both Mec1p and Tel1p can respond to a DSB, with distinct roles for these checkpoint kinases at different phases of the cell cycle. Part of this response involves histone phosphorylation over large chromosomal domains; however, the distinct distributions of gamma-H2AX and repair proteins near DSBs indicate that localization of repair proteins to breaks is not likely to be the main function of this histone modification.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chromatin / genetics*
  • Chromatin / metabolism
  • DNA Fragmentation / physiology*
  • DNA Repair / genetics
  • DNA Repair / physiology*
  • Deoxyribonucleases, Type II Site-Specific
  • Endodeoxyribonucleases / metabolism*
  • Exodeoxyribonucleases / metabolism*
  • Histones / metabolism*
  • Immunoprecipitation
  • Phosphorylation
  • Protein Isoforms / metabolism
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / metabolism*


  • Chromatin
  • Histones
  • Protein Isoforms
  • Saccharomyces cerevisiae Proteins
  • Endodeoxyribonucleases
  • Exodeoxyribonucleases
  • MRE11 protein, S cerevisiae
  • HO protein, S cerevisiae
  • SCEI protein, S cerevisiae
  • Deoxyribonucleases, Type II Site-Specific