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Published on: August 21, 2016
Transient relaxation of plasmid DNA in Escherichia coli by fluoroquinolones
M Matsuo1, Y Ohtsuka, K Kataoka
1Department of Microbiology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Abstract:
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.
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