Pruss G J, Manes S H, Drlica K
Cell. 1982 Nov;31(1):35-42. doi: 10.1016/0092-8674(82)90402-0.
Bacterial chromosomes and plasmid (pBR322) DNA from topoisomerase I-defective Escherichia coli strains have been characterized with respect to superhelical density. The topoisomerase I defect results in increased negative superhelical density of both the bacterial chromosome and pBR322. Thus topoisomerase I is involved in determining the level of supercoiling in bacteria. Three of the topoisomerase I-defective strains were studied carry secondary mutations that decrease superhelical density; these additional mutations are closely linked to the gyrB locus in two of the strains and to the gyrA locus in the third strain.
已对来自拓扑异构酶I缺陷型大肠杆菌菌株的细菌染色体和质粒（pBR322）DNA的超螺旋密度进行了表征。拓扑异构酶I缺陷导致细菌染色体和pBR322的负超螺旋密度增加。因此，拓扑异构酶I参与确定细菌中超螺旋的水平。研究了三个拓扑异构酶I缺陷型菌株，它们携带可降低超螺旋密度的二次突变；在其中两个菌株中，这些额外的突变与gyrB基因座紧密连锁，在第三个菌株中与gyrA基因座紧密连锁。
