FIG. 6.

Site-specific DNA cleavage by S. pneumoniae topoisomerase IV mediated by ciprofloxacin and its dimers. Plasmid pBR322 DNA linearized at its EcoRI site (0.4 μg) was incubated with ParC (0.45 μg) and GyrB (1.7 μg) in the absence or presence of dimer 1 or 2 or ciprofloxacin (CIP) at the indicated concentrations. After addition of SDS and proteinase K treatment, the DNA samples were analyzed by electrophoresis in a 1% agarose gel. Lanes M, a, and b, DNA size markers, linear pBR322, and linear pBR322 incubated with ParC and ParE in the absence of drug, respectively.