The IncB/O multiresistance plasmid R16, recovered in 1956 and used in experimental studies of B/O plasmid features, was sequenced. The resistance genes are all within a class 1 integron closely related to In1 containing the cassette array oxa2-aadA1-oxa2-orfD and the sul1 gene in the 3'-conserved segment (3'-CS), with Tn10, containing tetA(B), inserted just inside the 3'-CS. The integron is part of a 25,144 bp region inserted in the plasmid backbone, bounded on only one side by a truncated Tn6018 and flanked by a 4 bp duplication. Most of the 82,026 bp R16 backbone is almost identical to that of the B/O plasmid R805a. However, two short regions containing genes of unknown function are <95% identical to the corresponding regions of R805a, and were likely acquired from a related plasmid. The insertion in R16 is related to one in the I1 plasmid pSE69-3861-1, which is embedded at the same position in an almost 11 kb segment of R16 backbone. In pSE69-3861-1, Tn6018 is complete, and two regions previously seen only in AbaR type islands of GC1 Acinetobacter baumannii are present. One contains a top topoisomerase gene and the second contains a resX resolvase gene. These regions are identical to the corresponding parts of AbaR islands. Thus, the complete sequence of R16 sheds light on the role of homologous recombination in the evolution of plasmid backbones and the acquisition of antibiotic resistance genes by I-complex plasmids, as well as on the formation of the AbaR islands of GC1 A. baumannii.

中文翻译：

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1956年的B / O质粒R16携带一个In1样的1类整合子，该整合子嵌入包含鲍曼不动杆菌AbaR抗性岛部分的复杂区域。

对在1956年回收并用于B / O质粒特性实验研究的IncB / O多抗质粒R16进行了测序。抗性基因都在与In1密切相关的1类整合子中，In1包含盒阵列oxa2-aadA1-oxa2-orfD和3'保守区段（3'-CS）中的sul1基因，Tn10包含tetA（B ），插入3'-CS内。整合子是插入质粒主链中的25,144 bp区域的一部分，仅在一侧被截短的Tn6018结合，并在其侧翼有4 bp重复。82,026 bp的R16主链大部分与B / O质粒R805a几乎相同。但是，两个含有未知功能基因的短区与R805a的相应区<95％相同，很可能是从相关质粒中获得的。R16中的插入与I1质粒pSE69-3861-1中的一个相关，该质粒嵌入在R16主链几乎11 kb片段的相同位置。在pSE69-3861-1中，Tn6018是完整的，并且存在两个以前仅在GC1鲍曼不动杆菌的AbaR型岛中可见的区域。一个包含一个顶部拓扑异构酶基因，另一个包含一个resX resolvase基因。这些区域与AbaR岛的相应部分相同。因此，R16的完整序列阐明了同源重组在质粒主链的进化和I-复合质粒对抗生素抗性基因的获取中的作用，以及在GC1鲍曼不动杆菌AbaR岛的形成中的作用。存在两个以前仅在GC1鲍曼不动杆菌的AbaR型岛中看到的区域。一个包含一个顶部拓扑异构酶基因，另一个包含一个resX resolvase基因。这些区域与AbaR岛的相应部分相同。因此，R16的完整序列阐明了同源重组在质粒主链的进化和I-复合质粒对抗生素抗性基因的获取中的作用，以及在GC1鲍曼不动杆菌AbaR岛的形成中的作用。存在两个以前仅在GC1鲍曼不动杆菌的AbaR型岛中看到的区域。一个包含一个顶部拓扑异构酶基因，另一个包含一个resX resolvase基因。这些区域与AbaR岛的相应部分相同。因此，R16的完整序列阐明了同源重组在质粒主链的进化和I-复合质粒对抗生素抗性基因的获取中的作用，以及在GC1鲍曼不动杆菌AbaR岛的形成中的作用。