title: Relaxation of supercoiled DNA associated with induction of heat shock proteins in Escherichia coli.
abstract: 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 gyr A 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.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Mizushima
authors.forename: S
authors.initials: S
authors.lastname: Natori
authors.forename: K
authors.initials: K
authors.lastname: Sekimizu
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D018834:Chaperonin 60; D002746:Chlorpromazine / Q000494:pharmacology; D004278:DNA, Superhelical / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D000431:Ethanol / Q000494:pharmacology; D005798:Genes, Bacterial; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006358:Hot Temperature; D007700:Kinetics; D009268:Nalidixic Acid / Q000494:pharmacology; D009675:Novobiocin / Q000494:pharmacology; D013997:Time Factors; D059005:Topoisomerase II Inhibitors
chemical_list: D001426:Bacterial Proteins; D018834:Chaperonin 60; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D059005:Topoisomerase II Inhibitors; D009675:Novobiocin; D009268:Nalidixic Acid; D000431:Ethanol; C063842:dnaK protein, E coli; D002746:Chlorpromazine