Figure 3. Gsx2 forms a canonical HD fold with three major contacts within the major and minor DNA grooves.
X-ray crystal structure of Gsx2 203–264 (HD) bound to DNA containing the consensus motif TAATTA. (A) A single Gsx2HD-DNA complex shows the classic HD three helix fold, with the third helix inserted into the major groove of DNA. Gsx2 is colored cyan while DNA is colored grey, except for the -TAATTA- motif, which is colored green. N- and C-terminal ends are labeled. (B) A water molecule mediates hydrogen bond interactions between Q252 (Q50) of the HD and two thymine bases within the major groove. (C) Highly conserved N253 (N51) makes two direct hydrogen bonds with an adenine in the major groove. (D) R207 (R5) makes two direct hydrogen bonds with a thymine and an adenine in the minor groove. (E) Schematic of all specific and nonspecific protein-DNA interactions.