Fig. 1

Crystal structure of Mtb DnaE1. a Stereo image of the polymerase with domains indicated in different colors. The catalytic residues of the polymerase are shown in red sticks and the three metals in the PHP-exonuclease site are shown in blue spheres. b Stereo image of the polymerase, rotated by 90° from the view in (a). c Example of the electron density showing clearly defined side chains. Electron density shown at 2.1σ in gray. A stereo image is shown in Supplementary Fig. 1a. d Modeling of dsDNA into the polymerase active site reveals an almost perfect overlap between the DNA backbone and two SO₄ ²⁻ ions that are bound in the polymerase active site. See also Supplementary Fig. 1b for a comparison to other polymerases