FIGURE 1.

A RecA K72R challenge of wild type RecA protein filaments reveals RecA filament dynamics, whereas a challenge with RecA E38K/K72R does not. Wild type RecA filaments formed on cssDNA were challenged with RecA K72R or RecA E38K/K72R, and the rate of wild type RecA-catalyzed ATP hydrolysis was monitored over time. ATPase assays were carried out as described under “Experimental Procedures.” Each reaction contained 4 μm M13mp18 cssDNA, 2 μm wild type RecA, 3 mm ATP, 0.4 μm SSB, and 4 μm RecA K72R or 4 μm E38K/K72R or an equivalent volume of RecA storage buffer. The challenge was made after 50 min of wild type RecA and cssDNA incubation.