Figure 6.

Cleavage at the crux of an immobile Holliday junction. The sequence of the immobile junction in the vicinity of the crossover is depicted in a square planar conformation. The topoisomerase cleavage site is indicated by an arrow. Reaction mixtures containing 5 nM immobile junction (5′-labeled on strand 2) and 0, 5, 10 or 25 nM topoisomerase were incubated at 37°C for 15 min. The protease-digested DNA products were analyzed by denaturing gel electrophoresis as described in the legend to Figure 4. An autoradiograph of a gel is shown. The positions and chain lengths of the input 66mer strand 2 (66mer) and a 5′-labeled 24mer marker strand are indicated to the left. Labeled DNA–peptide adducts (Cl) are indicated by the bracket to the right.