Figure 1.

(A) Front view of Staphylococcus aureus DNA gyrase (PDB ID 6QX2 [13]), representative of the structure of type II topoisomerases. (B) Top view of S. aureus DNA gyrase, rotated 90° forwards from (A). The GyrA/ParC units of topoisomerase (green and red cartoons) are known to be critical to the actions of DNA strand breakage and covalent linkage of the phosphate backbone (whole DNA segment in pink spheres) to a conserved tyrosine residue in the active site, whilst the GyrB/ParE units (yellow and blue cartoons) are required for interactions with ATP. Both of these interactions are putative targets for topoisomerase inhibitors.