Backbone 1H, 13C and 15N Resonance Assignment of the N-Terminal 24 kDa Fragment of the gyraseb Subunit from E. Coli

DNA topoisomerases are ubiquitous enzymes that control the topological state of DNA in cells. Among them, bacterial DNA-gyrase is able to introduce supercoils into DNA in a reaction coupled to hydrolysis of ATP. Gyrase is essential in all bacteria but it is not found in eukaryotes and is therefore a good target for antibiotics. Gyrase consists of 2 subunits GyrA and GyrB, the active enzyme being an A2B2 complex. The ATPase reaction takes place in the B subunit and binding sites of different inhibitors have been localised in the N-terminal 24KDa fragment of GyrB (P24). The X-ray structures of this fragment complexed with different ligands have been published but structural studies in solution are scarce. In the present work, the fragment P24 was investigated by heteronuclear NMR both in the free form and as a complex with the cyclothialidine GR1222222. Backbone assignment for the 2 forms was obtained using TROSY-based triple resonance experiments on a triply labelled sample (100%15N, 100%13C, 75% 2H) of P24 from E. coli.