Figure 4. Functional expression of purified LdTopIΔ⁵⁶¹ΔL/ΔS truncation.

A) Two-fold serial dilutions of truncation LdTopIΔ⁵⁶¹ΔL/ΔS were assayed in a plasmid DNA relaxation assay for 30 min at 37°C. B) Time-course experiment of topoisomerase activity using 0.2 µg of truncation LdTopIΔ⁵⁶¹ΔL/ΔS per reaction C) Spot tests showing the sensibility to CPT of MBY3 yeast strain transformed with the “empty” pESC-URA vector (“mock”) or carrying the wild type LdTopIL/S genotype and deletion LdTopIΔ⁵⁶¹ΔL/ΔS D) Dose-response curves of these transformed yeast to different concentrations of CPT. A, B and C are pictures representatives of multiple experiments. D is the average of four independent experiments. Relaxation rate was compared with lane RfII which includes 0.3 µg of Φ X174 relaxed DNA. The “c” lane corresponds to an activity control, using a commercial topoisomerase.