Overall Structures of Mycobacterium tuberculosis DNA Gyrase Reveal the Role of a Corynebacteriales GyrB-Specific Insert in ATPase Activity

Despite sharing common features, previous studies have shown that gyrases from different species have been modified throughout evolution to modulate their properties. Here, we report two crystal structures of Mycobacterium tuberculosis DNA gyrase, an apo and AMPPNP-bound form at 2.6-Å and 3.3-Å resolution, respectively. These structures provide high-resolution structural data on the quaternary organization and interdomain connections of a gyrase (full-length GyrB-GyrA57)2 thus providing crucial inputs on this essential drug target. Together with small-angle X-ray scattering studies, they revealed an “extremely open” N-gate state, which persists even in the DNA-free gyrase-AMPPNP complex and an unexpected connection between the ATPase and cleavage core domains mediated by two Corynebacteriales-specific motifs, respectively the C-loop and DEEE-loop. We show that the C-loop participates in the stabilization of this open conformation, explaining why this gyrase has a lower ATPase activity. Our results image a conformational state which might be targeted for drug discovery. [Display omitted] •The N-gate of GyrBA57 (Mtb) gyrase lies in an “extremely open” conformation•The N-gate stays open in the crystal and in solution even in the presence of AMPPNP•The C-loop (a Corynebacteriales-specific GyrB insert) stabilized this conformation•This C-loop plays a role in the ATPase activity of the enzyme Petrella et al. present structures and SAXS data of Mycobacterium tuberculosis DNA gyrase highlighting a specific open N-gate conformation. They show that both the apo- and AMPPNP-bound gyrase N gates stay open in the crystal and in solution. This resting state is stabilized by a Corynebacteriales-specific GyrB insert called C-loop.