FIGURE 6.

DNA minor groove binders inhibit the positive supercoiling activity of Rad52^1-212. A, structures of distamycin A, netropsin, and pentamidine. B, topoisomerase I-mediated relaxation assay in the presence of minor groove binding ligands. Increasing concentrations of the ligands with or without 2 μm Rad52^1-212. Lanes 12, 24, and 36 show the addition of the ligands before E. coli topoisomerase I. C, DNA binding activity of Rad52^1-212 in the presence of the ligands. Negatively supercoiled plasmid DNA (pGsat4, 3.2 kilobases) was used.