FIG. 4.

Homology of the 3′ acceptor tail to the donor complex enhances flap ligation. The 5′-tailed 3′-blunt covalent topoisomerase-DNA intermediate was reacted with acceptor B, and the products were analyzed by polyacrylamide gel electrophoresis. An autoradiogram of the gel is shown in the left panel. The strand transfer reaction times are specified above the lanes. ", seconds; ′, minutes. A control reaction mixture containing the 5′ ³²P-labeled 60-mer substrate and no topoisomerase was analyzed in lane −. The extents of recombinant formation (as percentages of total labeled DNA) are plotted as a function of time in the right panel. The reaction pathway is illustrated at the top and discussed in the text.