CHANGES IN THE LINKING NUMBER OF SUPERCOILED DNA ACCOMPANY GROWTH TRANSITIONS IN ESCHERICHIA-COLI
CHANGES IN THE LINKING NUMBER OF SUPERCOILED DNA ACCOMPANY GROWTH TRANSITIONS IN ESCHERICHIA-COLI
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DOI：
10.1128/jb.169.10.4499-4506.1987
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发表时间：
1987-10-01
影响因子：
3.2
通讯作者：
GRALLA, JD
中科院分区：
文献类型：
--
作者：
BALKE, VL;GRALLA, JD
质粒DNA的超卷曲水平是从大肠杆菌中确定的，这种大肠杆菌的生长方式已知会改变基因表达和新陈代谢的全球模式。DNA超螺旋的变化被证明发生在几种类型的营养上移和下移中。超螺旋最显著的变化出现在饥饿的细胞中，其中两种不同松弛的质粒群被证明共存。因此，外部营养环境的一些变化导致细胞重组其全球新陈代谢，也导致伴随而来的DNA超级卷曲的变化。二硝基苯酚的实验结果表明，观察到的松弛可能不是由于ATP池的减少。当利福平被用来释放被RNA聚合酶限制的超级螺旋时，细胞拓扑异构酶的反应是移除这些新的、不受限制的超级螺旋。我们将这些结果解释为意味着细胞拓扑结构在DNA中保持恒定的超螺旋能量，除非在某些生长过渡期间，当代谢和基因表达的变化伴随着DNA超螺旋的变化。
The supercoiling levels of plasmid DNA were determined from Escherichia coli which was grown in ways that are known to alter global patterns of gene expression and metabolism. Changes in DNA supercoiling were shown to occur during several types of these nutrient upshifts and downshifts. The most dramatic change in supercoiling was seen in starved cells, in which two populations of differentially relaxed plasmids were shown to coexist. Thus, some changes in the external nutritional environment that cause the cells to reorganize their global metabolism also cause accompanying changes in DNA supercoiling. Results of experiments with dinitrophenol suggested that the observed relaxations were probably not due to reduced pools of ATP. When rifampin was used to release supercoils restrained by RNA polymerase, the cellular topoisomerases responded by removing these new, unrestrained supercoils. We interpret these results as implying that the cellular topological machinery maintains a constant superhelical energy in the DNA except during certain growth transitions, when changes in metabolism and gene expression are accompanied by changes in DNA supercoiling.