Involvement of DNA superhelicity in minichromosome maintenance in Escherichia coli.
Involvement of DNA superhelicity in minichromosome maintenance in Escherichia coli.
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DNA 超螺旋参与大肠杆菌微型染色体的维持。
DOI：
10.1128/jb.161.2.687-695.1985
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发表时间：
1985
影响因子：
3.2
通讯作者：
Helmstetter,CE
中科院分区：
文献类型：
--
作者：
Leonard,AC;Whitford,WG;Helmstetter,CE
有证据表明，大肠杆菌微型染色体的超螺旋密度低于其他大肠杆菌。大肠杆菌质粒，但可比的染色体。当引入gyrB减少超螺旋突变体，微型染色体是更不稳定的比正常或增加超螺旋特性的菌株，事实上，某些微型染色体衍生物不能引入顶端gyrB减少超螺旋突变体。这些观察结果是独特的微型染色体，因为维持质粒不复制oriC在这些突变体中没有改变。相同大小但具有不同限制性片段方向的微型染色体的分析表明，启动子-终止子功能的超螺旋依赖性改变，以及超螺旋对复制的直接影响，可能在观察到的微型染色体不稳定性中发挥作用。
Evidence is presented that Escherichia coli minichromosomes are harbored at superhelical densities which are lower than those measured for other E. coli plasmids but are comparable to that of the chromosome. When introduced into gyrB decreased-supercoiling mutants, minichromosomes were much more unstable than in strains with normal or increased supercoiling properties; in fact, certain minichromosome derivatives could not be introduced into top gyrB decreased-supercoiling mutants. These observations were unique to minichromosomes, since the maintenance of plasmids which did not replicate from oriC was not altered in these mutants. Analyses of minichromosomes of identical sizes but with different restriction fragment orientations suggested that supercoiling-dependent alterations in promoter-terminator functions, as well as direct effects of supercoiling on replication, may play a role in the observed minichromosome instability.