Structure of the BRCT Repeats of BRCA1 Bound to a BACH1 Phosphopeptide

Abstract

The recognition of the phosphorylated BACH1 helicase by the BRCA1 C-terminal (BRCT) repeats is important to the tumor suppressor function of BRCA1. Here we report the crystal structure of the BRCT repeats of human BRCA1 bound to a phosphorylated BACH1 peptide at 2.3 A resolution. The phosphorylated serine 990 and phenylalanine 993 of BACH1 anchor the binding to BRCA1 through specific interactions with a surface cleft at the junction of the two BRCT repeats. This surface cleft is highly conserved in BRCA1 across species, suggesting an evolutionarily conserved function of phosphopeptide recognition. Importantly, conserved amino acids critical for BACH1 binding are frequently targeted for missense mutations in breast cancer. These mutations greatly diminish the ability of BRCA1 to interact with the phosphorylated BACH1 peptide. Additional structural analysis revealed significant implications for understanding the function of the BRCT family of proteins in DNA damage and repair signaling.

Cleavage of the BRCT tandem domains of nibrin by the 657del5 mutation affects the DNA damage response less than the Arg215Trp mutation

“…Therefore, the BRCT domains present in both the 26-and the 70-kDa NBN fragments are involved in the dimerization of the two NBN fragments. Interestingly, several proteins containing BRCT domains interact with specific protein partners by BRCT-BRCT homointeractions and heterointeractions (27,(41)(42)(43).…”

The FHA and BRCT domains recognize ADP-ribosylation during DNA damage response

“…2E). Single mutation in the binding pocket of the BRCA1 BRCT domain abolished the interaction between the pSer motif and the BRCA1 BRCT domain (Shiozaki et al 2004). Based on the similarity of the secondary structure in the BRCT domain, we mutated the conserved Ser or Lys residues to disrupt the putative binding pocket in the BRCT domain of Ligase4 and XRCC1 ( Fig.…”

“…We also examined the binding pocket in the BRCT domains of Ligase4, XRCC1, BRCA1, and MDC1 because the structure of these BRCT domains has been solved (Zhang et al 1998;Sibanda et al 2001;Shiozaki et al 2004;Stucki et al 2005;Wu et al 2009;Campbell et al 2010;Cuneo et al 2011). However, the binding pockets in the BRCT domains of BRCA1 and MDC1 are much larger compared with those in the FHA domain.…”

“…For the comparison of the binding affinity between iso-ADP-ribose, peptides, and the FHA domain, five amino acids neighboring the pSer or pThr (capped with ACE and NME at their N and C termini) from the peptides comparable with the size of the iso-ADP-ribose were used in the binding free energy calculations. For the BRCT domain proteins, crystal structures of MDC1/peptide (pS-QEY; PDBID: 3K05) (Campbell et al 2010), BRCA1/peptide (ISRST-pS-PTFNK; PDB ID: 1T29) (Shiozaki et al 2004), NMR (nuclear magnetic resonance) structure of Ligase4 (PDB ID: 2E2W), and XRCC1 (PDB ID: 2D8M) were used.…”

Molecular Basis for the Association of Microcephalin (MCPH1) Protein with the Cell Division Cycle Protein 27 (Cdc27) Subunit of the Anaphase-promoting Complex

“…In vitro phosphopeptide interaction screens along with the crystal structures of BRCA1-and MDC1-phosphopeptide complexes have helped define a consensus BRCT binding phosphoprotein interaction site (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). This consensus binding site conforms to the pS/XXX rule where pS is a phosphoserine and X is any residue, with position pSϩ3 usually being a phenylalanine (BRCA1) or tyrosine (MDC1) or an aliphatic residue (TopBP1, Brc1, and Crb2), and possibly an aspartate in the sequence recognized by NBS1 tandem BRCT domains (24).…”