del Solar G, Moscoso M, Espinosa M
Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.
Mol Microbiol. 1993 May;8(5):789-96. doi: 10.1111/j.1365-2958.1993.tb01625.x.
Rolling circle-replicating plasmids constitute a group of small, promiscuous multicopy replicons spread among eubacteria. Until recently, rolling circle replication seemed to be limited to small plasmids from Gram-positive hosts and to single-stranded bacteriophages from Gram-negative bacteria. However, characterization of two small plasmids from Gram-negative hosts has shown that this replication mechanism is general among eubacteria. This review focuses on a family of highly related promiscuous plasmids that replicate by the rolling circle mechanism, and that have been isolated from various Gram-positive bacteria and from the Gram-negative bacterium Helicobacter. They all share homologies at the leading-strand origins and at the initiator of replication proteins. The plasmids of this family have directly repeated sequences at their plus origin of replication, which is located 5' from the start point of the mRNA for the initiation of replication protein. Replication is controlled by an antisense RNA and by a transcriptional repressor protein. The features and regulatory circuits of replication of this plasmid family seem to be unique among rolling circle-replicating plasmids. Members of this family replicate autonomously in Gram-positive and -negative hosts.
滚环复制质粒构成了一组小型、可在多种细菌中复制的多拷贝复制子，广泛分布于真细菌中。直到最近，滚环复制似乎还仅限于革兰氏阳性宿主的小质粒以及革兰氏阴性细菌的单链噬菌体。然而，对来自革兰氏阴性宿主的两个小质粒的特性分析表明，这种复制机制在真细菌中普遍存在。本综述聚焦于一类高度相关的可通过滚环机制复制的可在多种细菌中复制的质粒，它们已从各种革兰氏阳性细菌以及革兰氏阴性细菌幽门螺杆菌中分离出来。它们在先导链起始位点和复制蛋白起始因子处都具有同源性。该家族质粒在其正链复制起点处有直接重复序列，该起点位于复制蛋白起始mRNA起点的5'端。复制由反义RNA和转录阻遏蛋白控制。该质粒家族的复制特征和调控回路在滚环复制质粒中似乎是独特的。该家族成员可在革兰氏阳性和阴性宿主中自主复制。
