Human BRCA1-BARD1 ubiquitin ligase activity counteracts chromatin barriers to DNA resection

Ruth M. Densham, Alexander J. Garvin, Helen R. Stone, Joanna Strachan, Robert A. Baldock, Manuel Daza-Martin, Alice Fletcher, Sarah Blair-Reid, James Beesley, Balraj Johal, Laurence H. Pearl, Robert Neely, Nicholas H. Keep, Felicity Z. Watts, Joanna R. Morris

Research output: Contribution to journalArticlepeer-review


The opposing activities of 53BP1 and BRCA1 influence pathway choice in DNA double-strand-break repair. How BRCA1 counteracts the inhibitory effect of 53BP1 on DNA resection and homologous recombination is unknown. Here we identify the site of BRCA1-BARD1 required for priming ubiquitin transfer from E2∼ubiquitin and demonstrate that BRCA1-BARD1's ubiquitin ligase activity is required for repositioning 53BP1 on damaged chromatin. We confirm H2A ubiquitination by BRCA1-BARD1 and show that an H2A-ubiquitin fusion protein promotes DNA resection and repair in BARD1-deficient cells. BRCA1-BARD1's function in homologous recombination requires the chromatin remodeler SMARCAD1. SMARCAD1 binding to H2A-ubiquitin and optimal localization to sites of damage and activity in DNA repair requires its ubiquitin-binding CUE domains. SMARCAD1 is required for 53BP1 repositioning, and the need for SMARCAD1 in olaparib or camptothecin resistance is alleviated by 53BP1 loss. Thus, BRCA1-BARD1 ligase activity and subsequent SMARCAD1-dependent chromatin remodeling are critical regulators of DNA repair.

Original languageEnglish
Pages (from-to)647-655
Number of pages9
JournalNature Structural & Molecular Biology
Issue number7
Early online date30 May 2016
Publication statusPublished - 1 Jul 2016


  • BRCA1 Protein/genetics
  • Binding Sites
  • Camptothecin/pharmacology
  • Chromatin/chemistry
  • Cloning, Molecular
  • DNA Breaks, Double-Stranded
  • DNA Cleavage/drug effects
  • DNA Helicases/genetics
  • DNA, Neoplasm/genetics
  • Escherichia coli/genetics
  • Gene Expression
  • Gene Expression Regulation, Neoplastic
  • HeLa Cells
  • Histones/genetics
  • Humans
  • Models, Molecular
  • Phthalazines/pharmacology
  • Piperazines/pharmacology
  • Protein Binding
  • Recombinant Proteins/genetics
  • Recombinational DNA Repair
  • Signal Transduction
  • Tumor Suppressor Proteins/genetics
  • Tumor Suppressor p53-Binding Protein 1/genetics
  • Ubiquitin/genetics
  • Ubiquitin-Protein Ligases/genetics
  • Ubiquitination/drug effects


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