Fig. 2.

Details of DNA binding. Interaction of Glu61, Lys73, and Arg62 with bases is shown. HTH motif interaction in the major groove: base-specific interaction includes Glu71 (chain A) contacting three consecutive cytosine bases at positions 3, 4, and 5, Lys73 making hydrogen bonds to O6 and N7 of guanine (−5), and Arg62 interacting with adenine at −7 and guanine at −8. Direct interactions of His69 and Ser179 with phosphate are shown. The partial positive charge from the N-terminal end of helix H4 dipole also provides electrostatic interaction with the DNA phosphate backbone.