GSK126 enhances only single-stranded DNA breaks mediated by gyrase in the presence of ATP. The effects of GSK126 on single-stranded (SS, filled circles) and double-stranded (DS, empty circles) DNA cleavage mediated by B. anthracis (left, red), E. coli (middle, green), and M. tuberculosis (right, orange) gyrase in the presence of 1.5 mM ATP are shown. Error bars represent the SD of at least three independent experiments. Representative agarose gels are shown in Figure S4.