Structures and domain organization (PDB codes: 3V6P and 3V6T).

<p>(A) The structures of dHax3 in the DNA-free state (left) and DNA-bound state (right). Each structure contains an 11.5-repeat domain, forming a right-handed superhelical assembly. The 11.5 repeats are colored separately. (B) The 11.5-repeat domain mediates DNA binding. Each repeat recognizes one specific nucleotide by using the RVD residues at positions 12 and 13. Single-letter abbreviations for the amino acid residues are as follows: A, Ala; C, Cys; D, Asp; E, Glu; F, Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; V, Val; W, Trp; and Y, Tyr.