BRCA2的BRC重复序列调节RAD51的DNA结合选择性。
The BRC repeats of BRCA2 modulate the DNA-binding selectivity of RAD51.
作者信息
Carreira Aura, Hilario Jovencio, Amitani Ichiro, Baskin Ronald J, Shivji Mahmud K K, Venkitaraman Ashok R, Kowalczykowski Stephen C
机构信息
Department of Microbiology, University of California, Davis, CA 95616, USA.
出版信息
Cell. 2009 Mar 20;136(6):1032-43. doi: 10.1016/j.cell.2009.02.019.
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, approximately 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.
乳腺癌易感蛋白BRCA2对重组DNA修复至关重要。BRCA2通过与八个保守的、约35个氨基酸的基序（BRC重复序列）相互作用，将RAD51递送至双链DNA（dsDNA）断裂处。在此我们表明，单独的BRC4促进RAD51组装到单链DNA（ssDNA）上，而非dsDNA上，以刺激DNA链交换。BRC4通过阻断ATP水解，从而维持RAD51-ssDNA细丝的活性ATP结合形式来发挥作用。单分子可视化显示，BRC4不会拆解RAD51-dsDNA细丝，而是阻止RAD51在dsDNA上成核。此外，BRCA2包含所有八个BRC重复序列的结构域表现出这种行为。这些结果表明，BRC重复序列以两种相反但功能上相互增强的方式调节RAD51与DNA的相互作用：将活性RAD51靶向ssDNA并阻止RAD51在dsDNA上成核。因此，BRCA2将RAD51募集到DNA断裂处，并且我们提出，BRC重复序列调节DNA结合选择性。
Zotero 插件