Increase in negative supercoiling of plasmid DNA in Escherichia coli exposed to cold shock

Tohru Mizushima, Kazuhiro Kataoka, Yasuyuki Ogata, Ryu Ichi Inoue, Kazuhisa Sekimizu

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Negative supercoiling of plasmid DNA in Escherichia coli cells can decrease transiently when exposed to heat shock. The effect of cold shock on DNA supercoiling was examined, and analysis by agarose gel electrophoresis in the presence of chloroquine revealed that negative supercoiling of plasmid DNA in cells increased when cells were exposed to cold shock. This increase was transient and was nil when the cells were pretreated with nalidixic acid, an inhibitor of DNA gyrase. In a mutant deficient in expression of HU protein, the increase in negative supercoiling of DNA by cold shock is less apparent than in wild-type cells. It is proposed that DNA gyrase and HU protein have a role in the DNA supercoiling reaction seen with cold shock.

Original languageEnglish
Pages (from-to)381-386
Number of pages6
JournalMolecular Microbiology
Issue number2
Publication statusPublished - 1997 Jan 1


ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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