The DNA-binding activities of rice RAD51A1 and RAD51A2.

<p>Circular φX174 ssDNA (20 µM) (A) or linear φX174 dsDNA (20 µM) (C) was incubated with rice RAD51A1, RAD51A2, or human RAD51 at 37°C for 10 min. The samples were then separated by 0.8% agarose gel electrophoresis in TAE buffer, and were visualized by ethidium bromide staining. Lanes 1–10 and 11–20 represent the reactions conducted with and without ATP, respectively. Lanes 1 and 11 indicate negative control experiments without protein. Lanes 2–4 and 12–14 represent the experiments conducted with RAD51A1. Lanes 5–7 and 15–17 represent the experiments conducted with RAD51A2. Lanes 8–10 and 18–20 represent the experiments conducted with human RAD51. The protein concentrations were 0.75 µM (lanes 2, 5, 8, 12, 15, and 18), 1.5 µM (lanes 3, 6, 9, 13, 16, and 19) and 3 µM (lanes 4, 7, 10, 14, 17, and 20). (B) Graphic representation of the relative migration distances of the RAD51A1- and RAD51A2-ssDNA complexes. The migration distances relative to the free DNA are plotted against the protein concentrations. (D) Competitive ssDNA- and dsDNA-binding. Circular φX174 ssDNA (20 µM) and linear φX174 dsDNA (20 µM) were incubated with rice RAD51A1, RAD51A2, or human RAD51 at 37°C for 10 min, under the 120 mM NaCl conditions. The samples were then separated by 0.8% agarose gel electrophoresis in TAE buffer, and were visualized by ethidium bromide staining. Lane 1 indicates negative control experiments without protein. Lanes 2–4, 5–7, and 8–10 represent the experiments conducted with RAD51A1, RAD51A2, and human RAD51, respectively. The protein concentrations were 0.9 µM (lanes 2, 5, and 8), 1.8 µM (lanes 3, 6, and 9), and 3.6 µM (lanes 4, 7, and 10).