Figure 7. Effect of NKX3.1 and CPT on the relaxation activity of reconstituted topoisomerase I peptides.

DNA-relaxation assays were performed as described in Figure 6 except that reconstituted topoisomerase I was used to induce DNA relaxation. The experiments were performed in the absence or presence of NKX3.1 and with or without CPT as indicated. (A) Characterization of the DNA-relaxation activity of the reconstituted topoisomerase I peptides 6 and 12 without (upper panel) or with (lower panel) 50 μM CPT in the absence or presence of NKX3.1 as indicated. Relaxation activities were assayed by incubation at 37°C for the indicated time intervals. (B) Graphical representation of the relaxation activity quantified and calculated from the gels shown in (A), as described in the Experimental section, and plotted as a function of incubation time. (C) Characterization of the DNA relaxation activity of reconstituted topoisomerase I peptides 6 and 9 with or without 50 μM CPT and in the absence or presence of NKX3.1 as indicated.