Tse-Dinh Y C
Nucleic Acids Res. 1985 Jul 11;13(13):4751-63. doi: 10.1093/nar/13.13.4751.
The transcriptional control region of THE E. coli DNA topoisomerase I (topA) gene has been fused to the galactokinase (galK) gene coding region in a recombinant plasmid. In vivo synthesis of the galactokinase produced from such a plasmid has been measured and found to be reduced when mutations in the genes coding for DNA gyrase subunits are introduced into the cell or when gyrase inhibitors are present. In vitro transcription-translation of the galactokinase gene product confirms that a supercoiled DNA template is required for efficient transcription from the topA gene promoter. These results indicate that the amount of DNA topoisomerase I activity in E. coli is regulated by the extent of DNA supercoiling and can contribute to the overall modulation of DNA superhelicity and the expression of other genes.
大肠杆菌DNA拓扑异构酶I（topA）基因的转录控制区已在重组质粒中与编码半乳糖激酶（galK）基因的编码区融合。已对由此类质粒产生的半乳糖激酶的体内合成进行了测量，结果发现，当将编码DNA促旋酶亚基的基因突变引入细胞或存在促旋酶抑制剂时，半乳糖激酶的合成会减少。半乳糖激酶基因产物的体外转录-翻译证实，从topA基因启动子进行有效转录需要超螺旋DNA模板。这些结果表明，大肠杆菌中DNA拓扑异构酶I的活性量受DNA超螺旋程度的调节，并可有助于DNA超螺旋性的整体调节以及其他基因的表达。
