FIG 1.

Fluoroquinolone (FQ) sensitivity of mycobacterial gyrase. (A) FQ-induced plasmid DNA cleavage with M. tuberculosis DNA gyrase. A 100 nM concentration of the enzyme was incubated with 200 ng of pUC18 plasmid DNA and various concentrations (0.5 to 16 μM) of the different FQs (as indicated). The cleavage products were resolved on 1% agarose gel. Lane C, pUC18 DNA control. (B) Trapping of the gyrase-DNA complex by CFX and MFX. A total of 50 nM M. smegmatis DNA gyrase (MsGyr) was incubated with 5′-γ-³²P-labeled 72-bp DNA in the presence of 25 nM CFX or MFX in supercoiling reaction buffer at 37°C for 15 min. The DNA-bound complex was resolved on a 5% native polyacrylamide gel and visualized using a phosphorimager. The fold increase in gyrase-DNA complex formation in the presence of CFX and MFX was calculated with respect to the complex formed in the absence of any drug.