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- DNA Damage Response Pathway Uses Histone Modification to Ass...DNA Damage Response Pathway Uses Histone Modification to Assemble a Double-Strand Break-Specific Cohesin Domain
Molecular Cell, Volume 16, Issue 6, 22 December 2004, Pages 991-1002
Elçin Ünal, Ayelet Arbel-Eden, Ulrike Sattler, Robert Shroff, Michael Lichten, James E. Haber and Douglas Koshland
SummaryThe postreplicative repair of double-strand breaks (DSBs) is thought to require sister chromatid cohesion, provided by the cohesin complex along the chromosome arms. A further specialized role for cohesin in DSB repair is suggested by its de novo recruitment to regions of DNA damage in mammals. Here, we show in budding yeast that a single DSB induces the formation of a ∼100 kb cohesin domain around the lesion. Our analyses suggest that the primary DNA damage checkpoint kinases Mec1p and Tel1p phosphorylate histone H2AX to generate a large domain, which is permissive for cohesin binding. Cohesin binding to the phospho-H2AX domain is enabled by Mre11p, a component of a critical repair complex, and Scc2p, a component of the cohesin loading machinery that is necessary for sister chromatid cohesion. We also provide evidence that the DSB-induced cohesin domain functions in postreplicative repair.
Summary | Full Text | PDF (713 kb) - S. cerevisiae Tel1p and Mre11p Are Required for Normal Level...S. cerevisiae Tel1p and Mre11p Are Required for Normal Levels of Est1p and Est2p Telomere Association
Molecular Cell, Volume 24, Issue 4, 17 November 2006, Pages 603-610
Lara K. Goudsouzian, Creighton T. Tuzon and Virginia A. Zakian
SummaryIn diverse organisms, the Mre11 complex and phosphoinositide 3-kinase-related kinases (PIKKs), such as Tel1p and Mec1p from , are key mediators of DNA repair and DNA damage checkpoints that also function at telomeres. Here, we use chromatin immunoprecipitation (ChIP) to determine if Mre11p, Tel1p, or Mec1p affects telomere maintenance by promoting recruitment of telomerase subunits to telomeres. We find that recruitment of Est2p, the catalytic subunit of telomerase, and Est1p, a telomerase accessory protein, was severely reduced in Δ and Δ cells. In contrast, the levels of Est2p and Est1p binding in late S/G2 phase, the period in the cell cycle when yeast telomerase lengthens telomeres, were indistinguishable in wild-type (WT) and Δ cells. These data argue that Mre11p and Tel1p affect telomere length by promoting telomerase recruitment to telomeres, whereas Mec1p has only a minor role in telomerase recruitment in a cell.
Summary | Full Text | PDF (961 kb) - The role of the Mre11-Rad50-Xrs2 complex in telomerase- medi...The role of the Mre11-Rad50-Xrs2 complex in telomerase- mediated lengthening of Saccharomyces cerevisiae telomeres
Current Biology, Volume 11, Issue 17, 4 September 2001, Pages 1328-1335
Yasumasa Tsukamoto, Andrew K.P Taggart and Virginia A Zakian
SummaryThese data rule out models in which the MRX complex is necessary for Cdc13p binding to telomeres or in which the MRX complex is necessary for the catalytic activity of telomerase. Rather, the data suggest that the MRX complex is involved in recruiting telomerase activity to yeast telomeres.
Summary | Full Text | PDF (378 kb) - …more
Copyright © 2004 Elsevier Ltd. All rights reserved.
Current Biology, Volume 14, Issue 19, 1703-1711, 5 October 2004
doi:10.1016/j.cub.2004.09.047
Article
Distribution and Dynamics of Chromatin Modification Induced by a Defined DNA Double-Strand Break
Robert Shroff1, Ayelet Arbel-Eden2, Duane Pilch3, Grzegorz Ira2, William M. Bonner3, John H. Petrini4, James E. Haber2 and Michael Lichten*, 1, 
1 Laboratory of Biochemistry, Center for Cancer Research, National Cancer Institute, Building 37, Room 6124, Bethesda, MD 20892 USA
2 Rosenstiel Center and Department of Biology, Brandeis University, Waltham, MA 02454 USA
3 Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892 USA
4 Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10021 USA
Correspondence: Michael Lichten, +1 301 496-9760 (phone), +1 301 402-3095 (fax)Summary
Background: In response to DNA double-strand breaks (DSBs), eukaryotic cells rapidly phosphorylate histone H2A isoform H2AX at a C-terminal serine (to form γ-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 γ-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 γ-H2AX formation and equally rapid recruitment of the Mre11 repair protein. γ-H2AX formation was efficiently promoted by both Tel1p and Mec1p, the yeast ATM and ATR homologs; in G1-arrested cells, most γ-H2AX formation was dependent on Tel1 and Mre11. γ-H2AX formed in a large (ca. 50 kb) region surrounding the DSB. Remarkably, very little γ-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 γ-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.
