a 4.53 A resolution density map in Fig. 2a and a 3.23 A resolution map in Fig. 2b

A 4-nt G-C mismatched substrate yields a RAD51 mini-filament density map at 4.53 Å resolution. The density shows an unbent dsDNA interacting with two adjoining NTDs of the presynaptic filament, presenting the initial recruitment state of homologous dsDNA (Figure 2a). Increasing the mismatch to 8-nt yielded another density map at 3.23Å (Figure 2b), where dsDNA displayed pronounced curvature, interacting with four adjoining NTDs (N+1, N+2, N+3, and N+4). These two structures represent the recruitment of homologous dsDNA via nonspecific interactions of NTDs.