Mizushima T, Kataoka K, Ogata Y, Inoue R, Sekimizu K
Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Mol Microbiol. 1997 Jan;23(2):381-6. doi: 10.1046/j.1365-2958.1997.2181582.x.
Negative supercoiling of plasmid DNA in Escherichia coli cells can decrease transiently when exposed to heat shock. The effect of cold shock on DNA supercoiling was examined, and analysis by agarose gel electrophoresis in the presence of chloroquine revealed that negative supercoiling of plasmid DNA in cells increased when cells were exposed to cold shock. This increase was transient and was nil when the cells were pretreated with nalidixic acid, an inhibitor of DNA gyrase. In a mutant deficient in expression of HU protein, the increase in negative supercoiling of DNA by cold shock is less apparent than in wild-type cells. It is proposed that DNA gyrase and HU protein have a role in the DNA supercoiling reaction seen with cold shock.
当暴露于热休克时，大肠杆菌细胞中质粒DNA的负超螺旋会短暂降低。研究了冷休克对DNA超螺旋的影响，在氯喹存在下通过琼脂糖凝胶电泳分析发现，当细胞暴露于冷休克时，细胞中质粒DNA的负超螺旋增加。这种增加是短暂的，当用DNA回旋酶抑制剂萘啶酸预处理细胞时，这种增加就消失了。在HU蛋白表达缺陷的突变体中，冷休克引起的DNA负超螺旋增加不如野生型细胞明显。有人提出，DNA回旋酶和HU蛋白在冷休克时出现的DNA超螺旋反应中起作用。
