Figure 2.

Pif1 exhibited robust strand annealing activity in the absence of ATP and MgCl₂. (a) Schematic illustration for two partially complementary ssDNAs (70T-30nt and 30nt CS) annealing to generate a partial duplex DNA, 70T-30bp. Pif1 (200 nM) was incubated with 70T-30nt (2.6 nM) and 30nt CS (2 nM) for increasing times, and the reactions were stopped by mixing with a quench solution containing 200 mM EDTA, 1% SDS, 100 nM DNA trap, and 5 mg/mL dextran sulfate. (b) Representative gel images of annealed products formed in the presence of Pif1 (top) and in the absence of Pif1 (bottom) as a function of time. (c) Fraction of ssDNA annealed in the presence of Pif1 (circles). Spontaneous annealing was measured in the absence of Pif1 (diamonds). Error bars represent the standard deviation of three independent experiments.