Fig. 6

Structures of RecA and RecBCD bound to DNA. (a) Six E. coli RecA protein monomers were joined covalently by short peptide linkers and crystallized in the presence of ssDNA (d(T)₁₈) and an ATP analogue. The RecA monomers are in different colors. The ssDNA is in spacefill (From PDB ID 3CMU (Chen et al. 2008)). (b) The RecBCD enzyme from E. coli was crystallized bound to a DNA hairpin with a 19 bp stem and a 5 nt loop. The RecB subunit is in blue, RecC is red, and RecD is green. The nuclease domain of RecB is in the bottom, center, of the structure. Four base pairs at the end of the DNA hairpin are unwound in the RecBCD-DNA complex with the 3′-end bound to RecB and the 5′-end in RecC (From PDB ID 1 W36 (Singleton et al. 2004))