FIG. 5.

Generation of DNA cleavage by the yeast Top2p^T744P mutant in the presence of antibacterial quinolones. A 254-bp DNA fragment from the c-myc first intron was prepared. (A) Labeling of the upper DNA strand at position 3035. (B) Labeling of the lower DNA strand at position 3288. Drugs (100 μM each) and enzymes are indicated above the lanes. Lanes: yWT, yeast wild-type Top2p; Y T744P, Top2p^T744P. Numbers correspond to genomic positions of the nucleotide covalently linked to Top 2p. Double-headed arrows correspond to DNA cleavage sites with a 4-bp stagger that represent potential DNA double-strand breaks.