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.

对野生型大肠杆菌细胞进行热处理会导致负超螺旋质粒 DNA 松弛，随后发生重新超螺旋反应，恢复到 DNA 连接数的原始水平。没有证据表明 DNA 中的 DNA 扭转应变恢复gyrA 突变细胞。热处理后，DnaK 和 GroEL 蛋白在 gyrA 突变细胞中连续合成，但在野生型细胞中仅短暂合成。因此，DNA 超螺旋密度的变化与温度诱导的热休克蛋白表达相关。DNA 旋转酶抑制剂（萘啶酸、新生霉素）、有机溶剂（乙醇）和精神药物（氯丙嗪）都会刺激细胞 DNA 的松弛，在诱导 DnaK 和 GroEL 蛋白的相同浓度范围内，由于 DNA 松弛是通过热处理或 rpoH 突变体中的化学物质诱导的，因此该过程不是任何诱导合成的结果热休克蛋白。在rpoH和dnaK突变体中，没有发生再超螺旋反应，因此DnaK蛋白和其他热休克蛋白可能参与了该反应。我们认为，热处理诱导的 DNA 松弛会刺激参与 DNA 重新超螺旋的热休克蛋白的合成，从而阻止这些蛋白质的诱导。