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A study of the topological change of DNA in Escherichia coli induced by heat shock.

热激诱导大肠杆菌DNA拓扑变化的研究。

基本信息

批准号：
04680153
负责人：
SEKIMIZU Kazuhisa
金额：
$ 1.41万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04680153/
关键词：
DNA topology DNA supercoiling DNA topoisomerase DNA gyrase heat shock response heat shock proteins recombination Escherichia coli 熱ショック蛋白相同組み換え

项目摘要

Heat treatment of wild-type Escherichia coli cells leads to relaxation of negatively supercolied plasmid DNA, followed by a re-supercoiling reaction to the original level of the linking number of DNA.There was no evidence of the recovery of the DNA torsional strain in DNA of gyrA mutant cells. After heat treatment, DnaK and GroEL proteins were synthesized continuously in gyrA mutant cells but only transiently in wild-type cells. Thus, change in superhelical density of the DNA correlates with 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 induced DnaK and GroEL proteins, As DNA relaxation was induced by heat treatment or chemicals in an rpoH, mutant, the process is not the result of any induced synthesis of heat shock proteins.In rpoH and dnaK mutants, a re-supercoiling reaction did not occur, hence DnaK protein and other heat shock proteins presumably participate in the reaction. We propose that DNA relaxation induced by heat treatment stimulates synthesis of heat shock proteins involved in the re-supercoiling of DNA, which in turn shuts off the induction of these proteins.

热处理野生型大肠杆菌细胞导致负超螺旋的质粒DNA松弛，随后发生重超螺旋反应，使DNA的连接数恢复到原来的水平，而gyrA突变细胞的DNA没有恢复DNA扭转应变的迹象。热处理后，DnaK和GroEL蛋白在gyrA突变体细胞中连续合成，但在野生型细胞中仅瞬时合成。因此，DNA超螺旋密度的变化与温度诱导的热休克蛋白的表达相关。（萘啶酸、新生霉素）、有机溶剂（乙醇）和精神药物在诱导DnaK和GroEL蛋白的相同浓度范围内，所有的氯丙嗪都刺激了细胞DNA的松弛。由于在rpoH突变体中DNA松弛是由热处理或化学物质诱导的，在rpoH和dnaK突变体中，没有发生再超螺旋反应，因此推测DnaK蛋白和其它热休克蛋白参与了该反应。我们提出，热处理诱导的DNA松弛刺激参与DNA再超螺旋的热休克蛋白的合成，这反过来又关闭了这些蛋白的诱导。