James A A, Morrison P T, Kolodner R
Nature. 1983;303(5914):256-9. doi: 10.1038/303256a0.
Some plasmid DNAs, when maintained in wild-type Escherichia coli strains, form high levels of oligomeric species while others remain primarily monomers. One explanation of this observation is that the plasmids that do not form circular oligomers lack a DNA sequence necessary for the formation or maintenance of circular oligomeric species. Here we describe the isolation of segments of DNA from the E. coli genome and other sources that through a recA+ -dependent process: (1) stimulate the conversion of monomeric plasmids to different oligomeric forms, (2) stimulate the conversion of an oligomeric plasmid to a mixture of monomeric and different oligomeric forms, and (3) increase the frequency of recovery of figure-8 molecules. Both cis-acting and trans-acting elements were found. These elements seen to act by stimulating either the frequency of the recombination events that lead to the interconversion of different oligomeric plasmid DNA molecules or some process involved in the maintenance of newly-formed recombinant molecules.
一些质粒DNA在野生型大肠杆菌菌株中保存时会形成高水平的寡聚体，而其他质粒则主要保持为单体。对这一现象的一种解释是，不形成环状寡聚体的质粒缺乏形成或维持环状寡聚体所需的DNA序列。在此，我们描述了从大肠杆菌基因组和其他来源分离DNA片段的过程，这些片段通过recA+依赖的过程：（1）刺激单体质粒向不同寡聚体形式的转化；（2）刺激寡聚体质粒向单体和不同寡聚体形式混合物的转化；（3）增加8字形分子的回收频率。发现了顺式作用元件和反式作用元件。这些元件似乎通过刺激导致不同寡聚体质粒DNA分子相互转化的重组事件的频率或参与维持新形成的重组分子的某些过程来发挥作用。
