Microbiol Spectr. 2014 Oct;2(5). doi: 10.1128/microbiolspec.PLAS-0008-2013.
Conjugation is a key mechanism for horizontal gene transfer in bacteria. Some plasmids are not self-transmissible but can be mobilized by functions encoded in trans provided by other auxiliary conjugative elements. Although the transfer efficiency of mobilizable plasmids is usually lower than that of conjugative elements, mobilizable plasmids are more frequently found in nature. In this sense, replication and mobilization can be considered important mechanisms influencing plasmid promiscuity. Here we review the currently available information on two families of small mobilizable plasmids from Gram-positive bacteria that replicate via the rolling-circle mechanism. One of these families, represented by the streptococcal plasmid pMV158, is an interesting model since it contains a specific mobilization module (MOBV) that is widely distributed among mobilizable plasmids. We discuss a mechanism in which the promiscuity of the pMV158 replicon is based on the presence of two origins of lagging strand synthesis. The current strategies to assess plasmid transfer efficiency as well as to inhibit conjugative plasmid transfer are presented. Some applications of these plasmids as biotechnological tools are also reviewed.
conjugation 是细菌水平基因转移的关键机制。有些质粒不能自我传递，但可以通过其他辅助接合元件编码的功能来实现转移。虽然可移动质粒的转移效率通常低于接合元件，但在自然界中可移动质粒更为常见。从这个意义上说，复制和移动可以被认为是影响质粒混杂性的重要机制。本文综述了目前关于革兰氏阳性菌中小型可移动质粒的两个家族的信息，这些质粒通过滚环机制进行复制。其中一个家族以链球菌质粒 pMV158 为代表，它是一个有趣的模型，因为它包含一个广泛存在于可移动质粒中的特定移动模块 (MOBV)。我们讨论了一种机制，其中 pMV158 复制子的混杂性基于两条滞后链合成起始点的存在。目前评估质粒转移效率和抑制接合质粒转移的策略也被提出。还回顾了这些质粒作为生物技术工具的一些应用。
