Figure 3.

(A) Determination of the extent of DNA wrapping. Open-circular pBR322 (400 ng) was incubated for 30 min at 25°C with the enzyme/DNA ratios indicated and then the nick was resealed with E. coli ligase. The asterisk indicates the starting open-circular material. Samples were analyzed on an 1% agarose gel containing chloroquine at 0.4 μg/ml. (B) Stabilization of crossovers by A59₂B₂. Negatively supercoiled pBR322 (400 ng) was relaxed by topo I in the presence of the indicated ratios of enzyme/DNA, in the absence and presence of CFX. The tracks labeled with the asterisk contain the starting supercoiled material while those labeled 0 (zero) contain no enzyme and are fully relaxed by topo I. Samples were analyzed on an agarose gel containing chloroquine at 0.8 μg/ml.