Department of Cell and Molecular Biology, Microbiology, University of Gothenburg, Box 462, SE 413 46, Gothenburg, Sweden.
Nat Commun. 2011;2:268. doi: 10.1038/ncomms1267. Epub 2011 Apr 5.
Plasmids are important members of the bacterial mobile gene pool, and are among the most important contributors to horizontal gene transfer between bacteria. They typically harbour a wide spectrum of host beneficial traits, such as antibiotic resistance, inserted into their backbones. Although these inserted elements have drawn considerable interest, evolutionary information about the plasmid backbones, which encode plasmid related traits, is sparse. Here we analyse 25 complete backbone genomes from the broad-host-range IncP-1 plasmid family. Phylogenetic analysis reveals seven clades, in which two plasmids that we isolated from a marine biofilm represent a novel clade. We also found that homologous recombination is a prominent feature of the plasmid backbone evolution. Analysis of genomic signatures indicates that the plasmids have adapted to different host bacterial species. Globally circulating IncP-1 plasmids hence contain mosaic structures of segments derived from several parental plasmids that have evolved in, and adapted to, different, phylogenetically very distant host bacterial species.
质粒是细菌移动基因库的重要成员，也是细菌之间水平基因转移的最重要贡献者之一。它们通常携带着广泛的宿主有益特征，如抗生素抗性，插入到它们的骨架中。尽管这些插入元件引起了相当大的关注，但关于编码质粒相关特征的质粒骨架的进化信息却很少。在这里，我们分析了 25 个来自广泛宿主范围的 IncP-1 质粒家族的完整骨架基因组。系统发育分析显示出七个分支，其中我们从海洋生物膜中分离出来的两个质粒代表了一个新的分支。我们还发现，同源重组是质粒骨架进化的一个突出特征。基因组特征分析表明，这些质粒已经适应了不同的宿主细菌物种。因此，全球循环的 IncP-1 质粒包含了源自几个亲本质粒的片段的镶嵌结构，这些片段在不同的、系统发育上非常遥远的宿主细菌物种中进化并适应。
