Guiney D G, Deiss C, Simnad V
Department of Medicine, UCSD Medical Center.
Plasmid. 1988 Nov;20(3):259-65. doi: 10.1016/0147-619x(88)90032-7.
Transfer of plasmid DNA during bacterial conjugation begins at a specific site: the origin of transfer (oriT). The oriT region of the broad host range plasmid RK2 is located on a 250 bp fragment. Deletions involving either end of this region reduce transfer function, indicating that an extended sequence is required for optimal oriT activity. The single-strand nick induced by the RK2 DNA-protein relaxation complex is located adjacent to the 19 bp inverted repeat within the minimal oriT sequence. These results provide strong evidence that the plasmid relaxation event induced in vitro represents the nicking reaction that initiates DNA transfer at oriT during conjugation.
细菌接合过程中质粒DNA的转移始于一个特定位点：转移起点（oriT）。广宿主范围质粒RK2的oriT区域位于一个250 bp的片段上。涉及该区域任何一端的缺失都会降低转移功能，这表明需要一段延伸序列才能实现最佳的oriT活性。RK2 DNA-蛋白质松弛复合物诱导产生的单链切口位于最小oriT序列内19 bp反向重复序列的相邻位置。这些结果提供了强有力的证据，证明体外诱导的质粒松弛事件代表了在接合过程中在oriT处启动DNA转移的切口反应。
