POSITIVE SUPERCOILING OF DNA GREATLY DIMINISHES MESSENGER-RNA SYNTHESIS IN YEAST
POSITIVE SUPERCOILING OF DNA GREATLY DIMINISHES MESSENGER-RNA SYNTHESIS IN YEAST
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DOI：
10.1073/pnas.89.23.11461
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发表时间：
1992-12-01
影响因子：
11.1
通讯作者：
WANG, JC
中科院分区：
文献类型：
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作者：
GARTENBERG, MR;WANG, JC
在含有GAL1启动子连接的β-半乳糖苷酶基因的酿酒酵母细胞中，大肠杆菌DNA拓扑异构酶I的同时表达以及酵母DNA拓扑异构酶I和II的失活使β-半乳糖苷酶的细胞水平降低到无法检测的水平。细胞内mRNA水平和RNA聚合酶沿DNA的密度分析表明，这种减少是由于转录受到抑制，并且质粒携带的基因和染色体定位的基因都受到影响。这些结果被解释为由于DNA模板的正超卷曲而在体内抑制转录：在酵母DNA拓扑异构酶I和II都不存在的情况下，大肠杆菌DNA拓扑异构酶I优先去除转录产生的负超螺旋，导致细胞内DNA中正超螺旋的积累。在正常原核或真核细胞中，可能通过DNA拓扑异构酶的平衡作用避免了阳性超螺旋的积累。
In Saccharomyces cerevisiae cells harboring a GAL1 promoter-linked beta-galactosidase gene, the simultaneous expression of Escherichia coli DNA topoisomerase I and inactivation of yeast DNA topoisomerases I and II reduces the cellular level of beta-galactosidase to an undetectable level. Analysis of intracellular mRNA level and the density of RNA polymerase along DNA indicates that this reduction is due to the suppression of transcription and that both plasmid-borne and chromosomally located genes are affected. These results are interpreted in terms of inhibition of transcription in vivo due to positive supercoiling of the DNA template: preferential removal of transcription-generated negative supercoils by E. coli DNA topoisomerase I in the absence of both yeast DNA topoisomerases I and II results in the accumulation of positive supercoils in intracellular DNA. In normal prokaryotic or eukaryotic cells, accumulation of positive supercoils is presumably avoided through the balanced actions of DNA topoisomerases.