Fig. 3: Human topo IIα and IIβ are also highly processive on buckled DNA.

a The constant-extension experimental configuration, as shown in Fig. 2a (reshown here for clarity). All experiments shown in this figure were conducted on the 12.7 kb DNA clamped at 50% extension under (+) supercoiling. b Topo II activity traces of turns relaxed vs. time: yeast topo II (top panel, same traces as those used in Fig. 2c, d), human topo IIα (middle panel), and human topo IIβ (bottom panel) with N = 13, 5, and 5 biologically independent traces, respectively. Each color represents a measurement from a single DNA molecule, with an arrow of the same color indicating the first occurrence when the topo II paused for >30 s. For the dark blue trace of yeast topo II, topo II relaxation paused with duration >30 s at 430 s (and thus classified as no longer active at that time) and later showed a doubling of the rate beginning at 770 s, likely due to tandem relaxation by two topo II molecules. Source data are provided as a Source Data file.