Ramiro-Martínez Paula, de Quinto Ignacio, Lanza Val F, Gama João Alves, Rodríguez-Beltrán Jerónimo
Microbiology Department, Hospital Universitario Ramón y Cajal-IRYCIS, Madrid, Spain.
Escuela de Doctorado, Universidad Autónoma de Madrid, Madrid, Spain.
Nat Commun. 2025 Jul 2;16(1):6022. doi: 10.1038/s41467-025-61202-5.
Plasmids -autonomously replicating DNA molecules- exhibit a broad range of replication and mobility strategies, genetic repertoires, host ranges, sizes, and copies per cell. However, the determinants of plasmid copy number (PCN) remain poorly understood. Here, we use extensive DNA sequencing data to analyse the copy number of thousands of diverse bacterial plasmids in a comprehensive manner. We find that PCN is highly variable, spanning nearly three orders of magnitude, and that it is intrinsically robust against changes in genomic context. We further show that PCN variability is tightly associated with plasmid lifestyles, and propose the concept of replicon dominance to explain interactions in widespread multi-replicon plasmids. Finally, we uncover a universal scaling law that links copy number and plasmid size across bacterial species, indicating that pervasive constraints modulate the PCN-size trade-off.
质粒——自主复制的DNA分子——展现出广泛的复制和移动策略、基因库、宿主范围、大小以及每个细胞中的拷贝数。然而，质粒拷贝数（PCN）的决定因素仍知之甚少。在这里，我们使用大量的DNA测序数据，以全面的方式分析了数千种不同细菌质粒的拷贝数。我们发现PCN高度可变，跨度近三个数量级，并且它对基因组背景的变化具有内在的稳健性。我们进一步表明，PCN的变异性与质粒的生活方式紧密相关，并提出了复制子优势的概念来解释广泛存在的多复制子质粒中的相互作用。最后，我们发现了一条通用的标度律，该标度律将细菌物种间的拷贝数与质粒大小联系起来，表明普遍存在的限制因素调节了PCN与大小之间的权衡。
