Figure 1.

hRPA binding to ssDNA. (a) In a magnetic tweezer setup, an ssDNA molecule is tethered in between a glass slide and a paramagnetic bead. (b) hRPA binding curve taken at a stretching force of 3 pN. The reaction is initiated upon introduction of hRPA in the flow cell. A fast increase in the end-to-end distance is measured. The exponential shape of the binding curve indicates a low binding cooperativity (ω = 10–30). (c) Force-extension curves for bare ssDNA (green) and an ssDNA–hRPA complex (red) reveal an increase in hRPA-induced flexural rigidity and the prevention of hairpin formation. [NaCl]=30 mM. [hRPA]=3 nM.