Fig. 7: A magnesium ion coordinates drug binding to topo IV and DNA via multiple water-metal ion links.
From: Structural basis of topoisomerase targeting by delafloxacin
a, b Schematic representation of the water coordination spheres of delafloxacin chelated Mg2+ derived from 2.0 Å V-18 (a) and (better resolved) in 2.4 Å E18 (b) X-ray crystal structures of DNA cleavage complexes with topo IV (PDB ID: 8QMB). Important distances and likely hydrogen bonds are shown by dashed lines; only water molecules that could be individually imaged are shown (in red). c Imaging of the water molecule that forms a water-metal ion bridge between the delafloxacin and the ParC D83 sidechain (2mFo-DFc map contoured at 1.5σ) (PDB ID: 8C41).
