Danilevich V N, Volozhantsev N V, Stepanshin Iu G, Amosenko F A
Genetika. 1983 Oct;19(10):1582-92.
Integration of broad host range RP1 plasmid into the chromosome of Escherichia coli K-12 recA- cells has been studied. Using temperature-sensitive for replication plasmids pVD1 and pVD3, the derivatives of RP1, it has been shown that integration of RP1 into the bacterial chromosome results in formation of two classes of Hfr strains. Properties of these Hfrs have been examined. From the data obtained, it has been concluded that the plasmid integration and formation of one of the Hfrs classes appear to be mediated by transposon Tn1 residing on RP1. The other class of Hfr strains is formed due to a stable integration of RP1. In the course of analysis of R+ transconjugants arising at low frequency in crosses between stable Hfrs and E. coli rec+ recipients, it has been found that the significant part of them contain plasmid-chromosome hybrids (R-prim plasmids). On the basis of the latter results, a new simple method for R' plasmids selection has been proposed. Using restriction endonuclease analysis, the structure of plasmids that were excised from chromosomes of the stable Hfr strains and were comparable in their size to RP1, has been investigated. Probable mechanisms of the stable Hfr strains formation are discussed.
已对广宿主范围的RP1质粒整合到大肠杆菌K-12 recA-细胞染色体中的情况进行了研究。使用对复制敏感的温度敏感型质粒pVD1和pVD3（RP1的衍生物），结果表明RP1整合到细菌染色体中会导致形成两类高频重组（Hfr）菌株。已对这些Hfr菌株的特性进行了检测。根据所获得的数据，得出的结论是，质粒整合以及其中一类Hfr菌株的形成似乎是由位于RP1上的转座子Tn1介导的。另一类Hfr菌株是由于RP1的稳定整合而形成的。在分析稳定Hfr菌株与大肠杆菌rec+受体之间杂交时低频出现的R+转接合子的过程中，发现其中很大一部分含有质粒-染色体杂种（R-引物质粒）。基于后一结果，提出了一种新的简单的R'质粒选择方法。使用限制性内切酶分析，对从稳定Hfr菌株染色体上切除且大小与RP1相当的质粒结构进行了研究。讨论了稳定Hfr菌株形成的可能机制。
