Transient relaxation of plasmid DNA in Escherichia coli by fluoroquinolones.
We examined the influence of fluoroquinolones (norfloxacin, enoxacin, ofloxacin, levofloxacin, and sparfloxacin) on DNA supercoiling of plasmids in Escherichia coli cells by analysis with agarose gel electrophoresis in the presence of chloroquine. All the fluoroquinolones tested immediately induced DNA relaxation. The relaxed DNA was re-supercoiled, and the process was sensitive to chloramphenicol, suggesting that newly synthesized proteins participate in the reaction. The concentrations of fluoroquinolones required for DNA relaxation were much higher than those required for cell killing. The bactericidal effect of fluoroquinolones is apparently related to mechanisms other than DNA relaxation.
Department of Microbiology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
M
M
Matsuo
Y
Y
Ohtsuka
K
K
Kataoka
T
T
Mizushima
K
K
Sekimizu
D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis; D004269:DNA, Bacterial / Q000187:drug effects*; D004278:DNA, Superhelical / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D024841:Fluoroquinolones; D009690:Nucleic Acid Conformation / Q000187:drug effects; D010957:Plasmids / Q000187:drug effects*; D014161:Transduction, Genetic / Q000187:drug effects
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D024841:Fluoroquinolones