Gruss A, Ehrlich S D
Institut Jacques Monod, Paris, France.
J Bacteriol. 1988 Mar;170(3):1183-90. doi: 10.1128/jb.170.3.1183-1190.1988.
Plasmids pUB110, pC194, pE194, and pT181 are commonly used as cloning vectors in both Bacillus subtilis and Staphylococcus aureus. We report that insertion of foreign DNA into any of these plasmids results in the generation of high-molecular-weight plasmid multimers (HMW) of the recombinant, present as tandem head-to-tail copies. HMW was detected in wild-type B. subtilis and S. aureus strains. The production of HMW depended on the nature of the DNA insertion. Inserts of Escherichia coli DNA, e.g., pBR322 or pUC18, resulted in large amounts of HMW, whereas some inserts of S. aureus DNA of the same size had no effect on plasmid profile. The generation of HMW depended on the mode of plasmid replication; plasmids which replicate via a single-stranded DNA intermediate produced HMW upon foreign DNA insertion, whereas plasmid pAM beta 1, which does not generate single-stranded DNA, did not generate HMW. We propose that HMW is a product of imparied termination of rolling-circle replication and that the impairment is due to the nature of the DNA insertion.
质粒pUB110、pC194、pE194和pT181常用于枯草芽孢杆菌和金黄色葡萄球菌的克隆载体。我们报告，将外源DNA插入这些质粒中的任何一种都会导致重组体产生高分子量质粒多聚体（HMW），以头尾串联拷贝的形式存在。在野生型枯草芽孢杆菌和金黄色葡萄球菌菌株中检测到了HMW。HMW的产生取决于DNA插入的性质。大肠杆菌DNA的插入片段，如pBR322或pUC18，会导致大量HMW的产生，而相同大小的一些金黄色葡萄球菌DNA插入片段对质粒图谱没有影响。HMW的产生取决于质粒复制的方式；通过单链DNA中间体复制的质粒在插入外源DNA后会产生HMW，而不产生单链DNA的质粒pAM beta 1则不会产生HMW。我们提出，HMW是滚环复制终止受损的产物，而这种受损是由于DNA插入的性质所致。
