Acquisition of resistance genes by the IncQ plasmid R1162 is limited by its high copy number and lack of a partitioning mechanism
Acquisition of resistance genes by the IncQ plasmid R1162 is limited by its high copy number and lack of a partitioning mechanism
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DOI：
10.1128/jb.179.18.5947-5950.1997
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发表时间：
1997-09-01
影响因子：
3.2
通讯作者：
Meyer, RJ
中科院分区：
文献类型：
--
作者：
Becker, EC;Meyer, RJ
R1162是多拷贝质粒的宽宿主范围IncQ组的代表性成员。R1162的低拷贝数衍生物在体外构建并显示不稳定，表明在细胞分裂时质粒拷贝的分配是由于随机分布而不是主动分配机制，然而，R1162的正常拷贝数降低了肉汤中生长期间的细胞适应性，并有利于不稳定的低拷贝数变体的出现。因此，质粒携带的抗生素抗性基因在低拷贝数下有活性，最终导致质粒在无选择期间丢失。我们认为，R1162在人群中的维持需要一个基因，只有在高水平的选择。这降低了从其他R因子获得基因的可能性，并且可以解释天然存在的IncQ质粒所包含的抗生素抗性基因的种类有限。
R1162 is a representative member of the broad-host-range IncQ group of multicopy plasmids. Lower-copy-number derivatives of R1162 were constructed in vitro and shown to be unstable, indicating that partitioning of plasmid copies at cell division is due to random distribution and not to an active partitioning mechanism, However, the normal copy number of R1162 reduces cell fitness during growth in broth and favors the emergence of unstable, lower-copy-number variants. As a result, plasmid-borne antibiotic resistance genes active at a low copy number eventually result in plasmid loss during periods of no selection. We argue that the maintenance of R1162 in a population requires a gene that is selected only at high levels. This reduces the potential for acquiring genes from other R factors and could explain the limited variety of antibiotic resistance genes contained by naturally occurring IncQ plasmids.