EMSY is a large nuclear protein that binds to the transactivation domain of BRCA2. EMSY contains an approximately 100-residue segment at the amino terminus called the ENT (EMSY N-terminal) domain. Pla Show more
EMSY is a large nuclear protein that binds to the transactivation domain of BRCA2. EMSY contains an approximately 100-residue segment at the amino terminus called the ENT (EMSY N-terminal) domain. Plant proteins containing ENT domains also contain members of the royal family of chromatin-remodelling domains. It has been proposed that EMSY may have a role in chromatin-related processes. This is supported by the observation that a number of chromatin-regulator proteins, including HP1beta and BS69, bind directly to EMSY by means of a conserved motif adjacent to the ENT domain. Here, we report the crystal structure of residues 1-108 of EMSY at 2.0 A resolution. The structure contains both the ENT domain and the HP1beta/BS69-binding motif. This binding motif forms an extended peptide-like conformation that adopts distinct orientations in each subunit of the dimer. Biophysical and nuclear magnetic resonance analyses show that the main complex formed by EMSY and the chromoshadow domain of HP1 (HP1-CSD) consists of one EMSY dimer sandwiched between two HP1-CSD dimers. The HP1beta-binding motif is necessary and sufficient for EMSY to bind to the chromoshadow domain of HP1beta. Show less
The BRCA2 gene is mutated in familial breast and ovarian cancer, and its product is implicated in DNA repair and transcriptional regulation. Here we identify a protein, EMSY, which binds BRCA2 within Show more
The BRCA2 gene is mutated in familial breast and ovarian cancer, and its product is implicated in DNA repair and transcriptional regulation. Here we identify a protein, EMSY, which binds BRCA2 within a region (exon 3) deleted in cancer. EMSY is capable of silencing the activation potential of BRCA2 exon 3, associates with chromatin regulators HP1beta and BS69, and localizes to sites of repair following DNA damage. EMSY maps to chromosome 11q13.5, a region known to be involved in breast and ovarian cancer. We show that the EMSY gene is amplified almost exclusively in sporadic breast cancer (13%) and higher-grade ovarian cancer (17%). In addition, EMSY amplification is associated with worse survival, particularly in node-negative breast cancer, suggesting that it may be of prognostic value. The remarkable clinical overlap between sporadic EMSY amplification and familial BRCA2 deletion implicates a BRCA2 pathway in sporadic breast and ovarian cancer. Show less