Topoisomerase binding probe and method of use

A fluorescence polarization probe comprising an aminocoumarin conjugated to a fluorescent label, said probe operative as a fluorescent polarization probe of the ATP-binding site of prokaryotic DNA gyrase B or topoisomerase IV E subunit, wherein the aminocoumarin is a 3-amino-4,7-dihydroxycumarin ring moiety linked with a sugar moiety in 7-position and a benzoic acid derivative moiety in 3-position, and the fluorescent probe is linked to the benzoic acid derivative moiety;

• the aminocoumarin is novobiocin or clorobiocin;
• the fluorescent label is an acridine, a cyanine, a fluorone, an oxazin, a phenanthridine, a rhodamine or a BODIPY (boron-dipyrromethene);
• and
• the subunit is gyrase, B subunit of Francisella tularensis.