Most Acinetobacter plasmids are genus specific but their properties have not been investigated. Small plasmids with Rep_3 family replication initiation proteins and iterons are common in Acinetobacter baumannii and often carry antibiotic resistance genes and toxin-antitoxin systems. A RepAci1 plasmid, carrying the carbapenem resistance gene oxa23 in Tn2006 and a RepAci2 plasmid carrying the amikacin (kanamycin and neomycin) resistance gene aphA6 in TnaphA6 were identified. These two plasmids have related rep regions; the consensus 22 bp iteron repeats differ only at three positions and the RepA proteins are 84% identical. However, they were shown to be compatible, whereas the RepAci1 plasmid displaced another RepAci1 plasmid demonstrating that they were incompatible. Despite encoding no mobilisation proteins, the RepAci1 plasmid was transferred to a new host at low frequency when a conjugatively proficient RepAci6 plasmid was present, whereas the RepAci2 plasmid carrying mobA and mobC mobilisation genes was not. Comparison of the sequences of the mobilised and mobilising plasmids revealed a short region of high similarity that is upstream of the predicted mobilisation genes in the RepAci6 plasmid, and has an organisation similar to that of F-type oriT transfer origins. The segment carrying the oriT-like region is present in many RepAci1 plasmids, including ones carrying the cabarpenem resistance genes oxa24 or oxa58 in dif modules, and in some RepAci2 or other Rep_3 plasmids of further types, including one carrying the tet39 tetracycline resistance determinant. These plasmids are also likely to be mobilised, spreading resistance.

中文翻译：

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通过共轭RepAci6质粒动员携带oriT转移起点的小不动杆菌质粒。

大多数不动杆菌属质粒是属特异性的，但尚未研究其性质。带有Rep_3家族复制起始蛋白和iteron的小质粒在鲍曼不动杆菌中很常见，并且通常带有抗生素抗性基因和毒素-抗毒素系统。鉴定了在Tn2006中带有碳青霉烯抗性基因oxa23的RepAci1质粒和在TnaphA6中带有阿米卡星（卡那霉素和新霉素）抗性基因aphA6的RepAci2质粒。这两个质粒具有相关的rep区。共有的22 bp Iteron重复序列仅在三个位置不同，并且RepA蛋白具有84％的同一性。但是，它们被证明是兼容的，而RepAci1质粒取代了另一个RepAci1质粒，表明它们是不相容的。尽管没有编码动员蛋白，当存在结合熟练的RepAci6质粒时，将RepAci1质粒以低频率转移至新宿主，而没有携带mobA和mobC动员基因的RepAci2质粒。对动员质粒和动员质粒的序列进行比较，发现在RepAci6质粒中预测的动员基因上游有一个高度相似的短区域，其组织与F型oriT转移起点相似。带有oriT样区域的片段存在于许多RepAci1质粒中，包括在dif模块中携带Cabarpenem抗性基因oxa24或oxa58的质粒，以及在某些RepAci2或其他Rep_3进一步类型的质粒中，包括一个带有tet39四环素抗性决定簇的质粒。这些质粒也可能被动员，传播抗性。