FIG. 1.

Drug-promoted DNA breakage by wild-type S. pneumoniae DNA gyrase (A) and the mutant enzyme reconstituted with GyrA S81F (B). Supercoiled plasmid pBR322 DNA (0.4 μg) was incubated with recombinant S. pneumoniae GyrB (1.7 μg) and either wild-type GyrA (A) or GyrA S81F (B) (in each case, 0.45 μg) in the absence or presence of gemifloxacin (GEMI), moxifloxacin (MOXI), gatifloxacin (GATI), or levofloxacin (LEVO) at the indicated concentrations. Following treatment with SDS and proteinase K, the DNA products were examined in 1% agarose gels. Lanes a and b, supercoiled and linear pBR322, respectively; S, L, and N, supercoiled, linear, and nicked plasmid pBR322 bands, respectively.