γH2A binds Brc1 to maintain genome integrity during S‐phase |
| |
| Authors: | Claire L Dovey Grant Guenther John A Tainer Paul Russell |
| |
| Institution: | 1. Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA;2. Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, USA;3. Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA;4. Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA |
| |
| Abstract: | ATMTel1 and ATRRad3 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 (γH2A/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 γH2A 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. γH2A binding is critical for Brc1 function. The 1.45 Å resolution crystal structure of Brc1–γH2A 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 γH2A emerges as a critical chromatin‐specific response to replication‐associated DNA damage. |
| |
| Keywords: | chromatin DNA replication genome stability Schizosaccharomyces pombe X‐ray crystal structure |
|
|
