Fig. 6.

Proposed model for the interaction between RecBCD and χ. (A) Location of the χ-binding locus within RecBCD. Red and green residues are type 1 and type 2, respectively. Duplex DNA enters on left and exits at nuclease domain on right. Pre-χ recognition channels are orange; proposed post-χ recognition exit is magenta. The proposed exit path for ssDNA after χ recognition is shown. (B) Proposed alternative exit in RecBCD post-χ recognition. Path of ssDNA before χ recognition is in orange; the proposed alternative exit after χ recognition is shown in rose. Recognition helix is yellow and structural elements (blue) comprising the latch line alternative exit.