Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, 78712, USA.
Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA.
Nat Commun. 2019 Dec 20;10(1):5809. doi: 10.1038/s41467-019-13709-x.
Transmissible plasmids spread genes encoding antibiotic resistance and other traits to new bacterial species. Here we report that laboratory populations of Escherichia coli with a newly acquired IncQ plasmid often evolve 'satellite plasmids' with deletions of accessory genes and genes required for plasmid replication. Satellite plasmids are molecular parasites: their presence reduces the copy number of the full-length plasmid on which they rely for their continued replication. Cells with satellite plasmids gain an immediate fitness advantage from reducing burdensome expression of accessory genes. Yet, they maintain copies of these genes and the complete plasmid, which potentially enables them to benefit from and transmit the traits they encode in the future. Evolution of satellite plasmids is transient. Cells that entirely lose accessory gene function or plasmid mobility dominate in the long run. Satellite plasmids also evolve in Snodgrassella alvi colonizing the honey bee gut, suggesting that this mechanism may broadly contribute to the importance of IncQ plasmids as agents of bacterial gene transfer in nature.
可转移质粒将编码抗生素抗性和其他特性的基因传播到新的细菌物种中。在这里，我们报告说，具有新获得的 IncQ 质粒的大肠杆菌实验室种群经常会进化出带有辅助基因和质粒复制所需基因缺失的“卫星质粒”。卫星质粒是分子寄生虫：它们的存在降低了它们赖以继续复制的全长质粒的拷贝数。带有卫星质粒的细胞从减少辅助基因的累赘表达中立即获得了适应性优势。然而，它们保留了这些基因和完整质粒的副本，这使它们能够在未来受益并传播它们所编码的特性。卫星质粒的进化是短暂的。从长远来看，完全丧失辅助基因功能或质粒迁移能力的细胞占主导地位。卫星质粒也在定植于蜜蜂肠道的 Snodgrassella alvi 中进化，这表明这种机制可能广泛有助于 IncQ 质粒作为自然界中细菌基因转移的媒介的重要性。
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