FIGURE 5.

Wild type RecA and RecA K72R from shortened filaments on cssDNA when premixed in solution. Wild type RecA and RecA K72R were mixed in the same ratios as in Fig. 4 before the addition to cssDNA, and images of the resulting RecA filaments were obtained by EM as described under “Experimental Procedures.” The concentrations of DNA, RecA, ATP, and SSB are the same as in the legend to Fig. 4. A, images of RecA filaments at 0, 25, 50, and 75% RecA K72R were obtained at 15,000× magnification. B, more than 200 filaments at 0, 25, 50, and 75% RecA K72R were visually inspected and grouped into Full, Medium, Small, or Miscellaneous (Misc) length categories as described under “Experimental Procedures.” Bars represent the average percentage of RecA filaments in each length category as counted from four randomly selected squares on carbon grids containing spread reaction samples with 0, 25, 50, or 75% RecA K72R. Error bars represent 1 S.D. from the mean.