The BRC Repeats of BRCA2 Modulate the DNA-Binding Selectivity of RAD51

Aura Carreira, Jovencio Hilario, Ichiro Amitani, Ronald J. Baskin, Mahmud K K Shivji, Ashok R. Venkitaraman, Stephen C. Kowalczykowski

Research output: Contribution to journalArticlepeer-review

153 Scopus citations


The breast cancer susceptibility protein, BRCA2, is essential for recombinational DNA repair. BRCA2 delivers RAD51 to double-stranded DNA (dsDNA) breaks through interaction with eight conserved, ∼35 amino acid motifs, the BRC repeats. Here we show that the solitary BRC4 promotes assembly of RAD51 onto single-stranded DNA (ssDNA), but not dsDNA, to stimulate DNA strand exchange. BRC4 acts by blocking ATP hydrolysis and thereby maintaining the active ATP-bound form of the RAD51-ssDNA filament. Single-molecule visualization shows that BRC4 does not disassemble RAD51-dsDNA filaments but rather blocks nucleation of RAD51 onto dsDNA. Furthermore, this behavior is manifested by a domain of BRCA2 comprising all eight BRC repeats. These results establish that the BRC repeats modulate RAD51-DNA interaction in two opposing but functionally reinforcing ways: targeting active RAD51 to ssDNA and prohibiting RAD51 nucleation onto dsDNA. Thus, BRCA2 recruits RAD51 to DNA breaks and, we propose, the BRC repeats regulate DNA-binding selectivity.

Original languageEnglish (US)
Pages (from-to)1032-1043
Number of pages12
Issue number6
StatePublished - Mar 20 2009


  • DNA

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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