Mizushima T, Natori S, Sekimizu K
Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Mol Gen Genet. 1993 Apr;238(1-2):1-5. doi: 10.1007/BF00279523.
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.
野生型大肠杆菌细胞的热处理导致负超螺旋质粒DNA出现短暂松弛，而gyrA突变体细胞中的DNA没有恢复其扭转应变。热处理后，gyrA突变体细胞中持续合成DnaK和GroEL蛋白，而在野生型细胞中它们仅短暂合成。因此，DNA超螺旋密度的变化与热休克蛋白的温度诱导表达相关。DNA回旋酶抑制剂（萘啶酸、新生霉素）、一种有机溶剂（乙醇）和一种精神药物（氯丙嗪）在诱导热休克蛋白的相同浓度范围内均刺激细胞DNA松弛。由于rpoH突变体中的热处理或化学物质诱导了DNA松弛，所以该过程不是热休克蛋白诱导合成的结果。
