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EMBO J. 2010 Mar 17;29(6):1136-48. doi: 10.1038/emboj.2009.413. Epub 2010 Jan 21.

gammaH2A binds Brc1 to maintain genome integrity during S-phase.

Author information

  • 1Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA.

Abstract

ATM(Tel1) and ATR(Rad3) checkpoint kinases phosphorylate the C-terminus of histone H2AX (H2A in yeasts) in chromatin flanking DNA damage, establishing a recruitment platform for checkpoint and repair proteins. Phospho-H2A/X (gammaH2A/X)-binding proteins at double-strand breaks (DSBs) have been characterized, but those required for replication stress responses are unknown. Here, we present genetic, biochemical, small angle X-ray scattering (SAXS), and X-ray structural studies of the Schizosaccharomyces pombe Brc1, a 6-BRCT-domain protein that is structurally related to Saccharomyces cerevisiae Rtt107 and mammalian PTIP. Brc1 binds gammaH2A to form spontaneous and DNA damage-induced nuclear foci. Spontaneous Brc1 foci colocalize with ribosomal DNA repeats, a region prone to fork pausing and genomic instability, whereas DNA damage-induced Brc1 foci colocalize with DSB response factors. gammaH2A binding is critical for Brc1 function. The 1.45 A resolution crystal structure of Brc1-gammaH2A complex shows how variable BRCT insertion loops sculpt tandem-BRCT phosphoprotein-binding pockets to facilitate unique phosphoprotein-interaction specificities, and unveils an acidic DNA-mimicking Brc1 surface. From these results, Brc1 docking to gammaH2A emerges as a critical chromatin-specific response to replication-associated DNA damage.

PMID:
20094029
[PubMed - indexed for MEDLINE]
PMCID:
PMC2845269
Free PMC Article

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