Fig. 7.

Structure of the E. coli PutA DNA-binding domain. A, PutA52 dimer highlighting residues important for binding DNA. The two chains are colored green and red. Positions of residues of the β-sheet that form hydrogen bonds with DNA bases are indicated in yellow. Side chains of residues at the N-terminus of αB that interact with the DNA backbone are drawn as cyan sticks. B, Structure of PutA52 complexed with DNA, highlighting interaction of the protein β-sheet with the DNA major groove. Coloring of the protein is the same as in panel A. Selected protein side chains are drawn as spheres.