Shafferman A, Cohen S, Flashner Y
Mol Gen Genet. 1978 Sep 8;164(3):259-64. doi: 10.1007/BF00333155.
Insertion of DNA at the EcoRI site of ColE1 results in increase of immunity to colicin killing in E. coli harboring such recombinant ColE1 plasmid as compared to E. coli (ColE1). This effect is neither due to cis or trans interactions originating from the inserted foreign DNA fragment, nor to changes in plasmid copy number. This defect in the immunity mechanism is not trans complemented for by wild type ColE1. Increase in immunity can also be obtained by deleting a DNA segment from the ColE1 genome. This segment is approximately 120 bp left to the EcoRI site within the colicin structural gene. It is concluded that the structure of DNA per se, around the EcoRI site, within colcin structural gene, is the structure which affects immunity expression.
在携带此类重组ColE1质粒的大肠杆菌中，将DNA插入ColE1的EcoRI位点会导致其对大肠杆菌素杀伤的免疫力增强，与大肠杆菌（ColE1）相比。这种效应既不是由于插入的外源DNA片段产生的顺式或反式相互作用，也不是由于质粒拷贝数的变化。野生型ColE1不能对这种免疫机制缺陷进行反式互补。通过从ColE1基因组中删除一个DNA片段也可以获得免疫力的增强。该片段位于大肠杆菌素结构基因内EcoRI位点左侧约120 bp处。得出的结论是，大肠杆菌素结构基因内EcoRI位点周围的DNA本身结构是影响免疫表达的结构。
