Relaxation of supercoiled DNA associated with induction of heat shock proteins in Escherichia coli

Tohru Mizushima, Shunji Natori, Kazuhisa Sekimizu

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Heat treatment of wild-type Escherichia coli cells led to a transient relaxation of negatively supercoiled plasmid DNA and there was no recovery of DNA torsional strain in the DNA in gyrA mutant cells. After heat treatment, DnaK and GroEL proteins were synthesized continuously in the gyrA mutant cells, whereas they were synthesized only transiently in wild-type cells. Thus, change in superhelical density of the DNA correlated with the temperature-induced expression of heat shock proteins. Inhibitors of DNA gyrase (nalidixic acid, novobiocin), an organic solvent (ethanol) and a psychotropic drug (chlorpromazine) all stimulated relaxation of cellular DNA over the same concentration range that induces heat shock proteins. As DNA relaxation was induced by heat treatment or chemicals in an rpoH mutant, the process is not the result of induced synthesis of heat shock proteins.

Original languageEnglish
Pages (from-to)1-5
Number of pages5
JournalMGG Molecular & General Genetics
Issue number1-2
Publication statusPublished - 1993 Apr 1



  • DNA gyrase
  • DNA relaxation
  • DNA supercoiling
  • Heat shock response
  • rpoH

ASJC Scopus subject areas

  • Genetics

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