COBRE: UID: PROJ 2: EVOLUTION OF ANTIBIOTIC RESISTANCE PLASMIDS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 质粒是移动的遗传元件，其在细菌物种中抗生素抗性的分散中起核心作用，从而降低用于治疗感染性疾病的抗微生物剂的有效性。我们的研究目的是通过实验进化研究来辨别质粒进化的模式。特别是，我们的目标是确定一些质粒如何演变的能力，转移和保持在广泛的主机。64.5kb的IncP-1？选择质粒pB 10作为模型系统，因为其高转移性和宽宿主范围。对该质粒在污水处理厂细菌群落中的自然宿主范围的检查表明，pB 10转移到38个不同的物种。这些结果也表明，质粒的宿主范围不仅取决于固有的质粒特性，但由原始宿主和环境参数。从这些研究中，我们发现了两种宿主，其中质粒pB 10呈现出比在E. coli K12。在一个用这些宿主之一恶臭假单胞菌H2（pB 10）进行的进化实验中，质粒对于之前从未携带过质粒的同基因H2菌株（天然）的成本在1000代质粒进化后显著降低：从20%降低到9%或16%，这取决于质粒是否在同基因宿主之间定期转移。这些结果表明，质粒编码的适应性变化负责这种激烈的质粒宿主适应，分子基础正在研究中。同时，将三种天然存在的IncP-1质粒的基因组序列与已知的IncP-1质粒的基因组序列进行比较。相比之下，两个所有其他测序的IncP-1？质粒，质粒pB 3的oriV区域不被转座子中断，对这些混杂质粒的进化历史提供了新的线索。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Plasmids are mobile genetic elements that play a central role in the dispersion of antibiotic resistance among bacterial species, thereby decreasing the effectiveness of antimicrobial agents used for the treatment of infectious diseases. The objective of our research is to discern patterns of plasmid evolution through experimental evolution studies. In particular, we aim to determine how some plasmids have evolved the ability to transfer and be maintained in a wide range of hosts. The 64.5 kb IncP-1? plasmid pB10 was chosen as a model system because of its high transferability and broad host-range. An examination of the natural host-range of this plasmid in the bacterial community of a sewage treatment plant showed that pB10 transferred to 38 distinct species. These findings also suggested that the host-range of a plasmid was not only determined by intrinsic plasmid characteristics but by the original host and the environmental parameters. From these studies we found two hosts in which plasmid pB10 presents a higher burden or is less stable than in E. coli K12. In an evolution experiment with one of these hosts, P. putida H2 (pB10), the cost of the plasmid to an isogenic H2 strain that had never carried the plasmid before (na¿ve), was significantly decreased after 1000 generations of plasmid evolution: from 20% to 9% or 16%, depending on whether or not the plasmid was regularly transferred between isogenic hosts. These results indicate that plasmid-encoded adaptive changes were responsible for this drastic plasmid-host adaptation, and the molecular basis is being examined. In parallel, the genome sequences of three naturally occurring IncP-1 plasmids were compared with those of known IncP-1 plasmids. In contrast two all other sequenced IncP-1? plasmids, the oriV region of plasmid pB3 is not interrupted by transposons, shedding new light on the evolutionary history of these promiscuous plasmids.