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Mol Cell 2021 Jul 01;8113:2765-2777.e6. doi: 10.1016/j.molcel.2021.05.010.
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Structural insight into BRCA1-BARD1 complex recruitment to damaged chromatin.

Dai L , Dai Y , Han J , Huang Y , Wang L , Huang J , Zhou Z .

The BRCA1-BARD1 complex directs the DNA double-strand break (DSB) repair pathway choice to error-free homologous recombination (HR) during the S-G2 stages. Targeting BRCA1-BARD1 to DSB-proximal sites requires BARD1-mediated nucleosome interaction and histone mark recognition. Here, we report the cryo-EM structure of BARD1 bound to a ubiquitinated nucleosome core particle (NCPUb) at 3.1 Å resolution and illustrate how BARD1 simultaneously recognizes the DNA damage-induced mark H2AK15ub and DNA replication-associated mark H4K20me0 on the nucleosome. In vitro and in vivo analyses reveal that the BARD1-NCPUb complex is stabilized by BARD1-nucleosome interaction, BARD1-ubiquitin interaction, and BARD1 ARD domain-BARD1 BRCT domain interaction, and abrogating these interactions is detrimental to HR activity. We further identify multiple disease-causing BARD1 mutations that disrupt BARD1-NCPUb interactions and hence impair HR. Together, this study elucidates the mechanism of BRCA1-BARD1 complex recruitment and retention by DSB-flanking nucleosomes and sheds important light on cancer therapeutic avenues.

PubMed ID: 34102105
Article link: Mol Cell

Species referenced: Xenopus laevis
Genes referenced: bard1 brca1
GO keywords: nucleosome

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