Steck T R, Drlica K
Cell. 1984 Apr;36(4):1081-8. doi: 10.1016/0092-8674(84)90058-8.
Nucleoids isolated from a temperature-sensitive gyrB mutant of E. coli, incubated at restrictive temperatures, exhibit increased sedimentation rates and an abnormal doublet or dumbbell-shaped morphology. Shifting cells from restrictive to permissive temperature prior to nucleoid isolation leads to decreases in the percentage of doublet nucleoids and in nucleoid sedimentation rates. When nucleoids isolated from mutant cells exposed to restrictive temperature are incubated with purified gyrase, the percentage of doublet nucleoids decreases as the total number of nucleoids increases. These results, together with the demonstrated ability of gyrase to decatenate small circular DNA molecules in vitro, suggest that gyrase participates in bacterial chromosome segregation through its decatenating activity.
从大肠杆菌的温度敏感型gyrB突变体中分离出的类核，在限制温度下孵育时，沉降速率增加，呈现出异常的双峰或哑铃状形态。在类核分离之前将细胞从限制温度转移到允许温度，会导致双峰类核的百分比和类核沉降速率降低。当将从暴露于限制温度的突变细胞中分离出的类核与纯化的回旋酶一起孵育时，随着类核总数的增加，双峰类核的百分比会降低。这些结果，连同已证明的回旋酶在体外解开小环状DNA分子连环的能力，表明回旋酶通过其解连环活性参与细菌染色体分离。
