FIGURE 1.

Crystal structure of EF1143 in complex with dGTP and dTTP. A, general view of the EF1143 homo-tetramer bound to dGTP and dTTP (PDB ID: 4LRL). Each monomer is identified with distinct colors and labeled as chains A–D. The N-terminal catalytic domain of each subunit is colored in brighter tones, whereas the C-terminal subdomains are shown in pale shades. Dication metal atoms in the catalytic centers are shown as black spheres. dGTP (cyan spheres) occupies each of four primary allosteric sites, and dTTP (red spheres) occupies two (those of chains A and C) of four secondary regulatory sites. B, dGTP (cyan carbon atoms) binding at the primary allosteric site in 4LRL. Chains B, C, and D are shown in yellow, green, and orange, respectively. dTTP is shown in gray stick representation. H-bonds are depicted by dashed lines, and H-bond lengths are shown. This binding site was also described in our previous publication (23). C, details of the dTTP (pink carbon atoms) interaction at the secondary allosteric site of 4LRL. Chains B, C, and D are depicted as in B. A dGTP molecule, in the primary allosteric site, is shown in gray. Selected side chains are shown and labeled. H-bond lengths are indicated.