FIGURE 6.

DprA antagonizes the inhibitory effect of RecU on RecA filament extension. (A) Circular 3,199-nt ssDNA (10 μM) was preincubated with increasing DprA concentrations (5 min, 37°C) in buffer B containing 5 mM ATP. RecA (0.8 μM) was added and ATPase activity was measured (30 min, 37°C). (B) ssDNA was preincubated with increasing DprA concentrations and a fixed RecU amount (100 nM) (5 min, 37°C), followed by the addition RecA. ATPase activity was then measured. (C) ssDNA was preincubated with a fixed amount of RecA and increasing DprA concentrations (5 min, 37°C), followed by a fixed amount of RecU (100 nM), and ATPase activity was measured. ATPase activity was measured from the time of RecA addition. Representative graphics are shown here and quantification of the results are expressed as the mean ± SEM of >3 independent experiments (see Table 2).