Figure 3.

The presence of the T segment in the ATP-operated clamp promotes DNA cleavage. Negatively supercoiled DNA (10 nM; σ = −0.06) was incubated with 200 nM gyrase and 1.4 mM ADPNP, where indicated. The samples were treated with 0.2% SDS and 0.1 mg/ml proteinase K for 30 min at 37°C to reveal DNA cleavage, and the products were analyzed by agarose gel electrophoresis.