Figure 6.

The CL analogue NA1 does not promote topoisomerase IV-mediated DNA breakage. Supercoiled plasmid pBR322 was incubated with increasing amounts (12.5, 25, 50, 100, 200 µM) of CL (lanes 3–7) or NA1 (lanes 8–12) and after SDS-proteinase K treatment, DNA products were separated on a 1% agarose gel and visualized by ethidium bromide staining. Lanes 1 and 2 are controls for the input supercoiled plasmid DNA and for the cleavage activity of topoisomerase IV without drugs, respectively. Band identities are shown on the left. N, L and SC stand for nicked, linear and supercoiled plasmid DNA, respectively. For any given DNA sample, the percentage of nicked, linear and supercoiled DNA bands were determined by dividing the relevant band intensity by the total DNA intensity loaded into that particular track. Quantification data are shown below the gel figure.