COBRE: UID: PROJ 1: EVOLUTION OF ANTIBIOTIC RESISTANCE PLASMID HOST RANGE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 通过质粒结合转移抗生素耐药基因，极大地促进了耐药性在细菌病原体中的快速传播，从而降低了人类感染性疾病的各种治疗方案的有效性。有些质粒只在较小范围的宿主(NHR)中转移和稳定复制，而所谓的宽宿主范围(BHR)质粒在远缘细菌中转移和复制，从而使抗性基因跨越分类障碍。我们的长期目标是限制多药耐药对重要人类病原体的快速传播，但首先必须从根本上了解质粒宿主范围的进化。我们的总体假设是，质粒的宿主范围可以进化，就像寄生虫一样，随着进化时间的推移，会变得更宽或更窄。为了验证这一假说，我们提出了以下具体目标：1)阐明允许窄宿主范围的质粒扩大或改变其宿主范围的进化变化，以及2)阐明由于长期与单一宿主结合而导致宽宿主范围的质粒宿主范围收缩的进化变化。为了解决第一个目标，我们将在四个细菌宿主中进化NHR微型复制子mini-F，这些宿主显示出不同的初始水平的质粒稳定性。进化的质粒的DNA序列将被确定，以识别导致宿主范围转移或扩大的基因类型变化。我们推测，在一个较差的宿主中，导致稳定性提高的质粒适应也将提高其他宿主中的稳定性。在特定目标2下，我们将研究BHR微型复制子mini-pBP136的进化突变体，这些突变体最近被证明经历了宿主范围的变化。我们推测，观察到的变化是由于复制起始蛋白TrfA1与宿主解旋酶相互作用的变化。为实现这两个目标，将建立数学模型和统计分析，并用来确定影响这些演变过程的参数。与公共卫生相关：这项工作将揭开决定多重耐药质粒宿主范围的质粒-宿主相互作用的机制。这可能会揭示特定药物治疗的诱人目标，以对抗人类病原体中令人震惊的耐药性传播。

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. Conjugative transfer of antibiotic resistance genes by plasmids has greatly contributed to the rapid spread of drug resistance among bacterial pathogens, thereby decreasing the effectiveness of various treatment options for infectious diseases in humans. While some plasmids only transfer and stably replicate in a narrow range of hosts (NHR), so-called broad-host-range (BHR) plasmids transfer and replicate in distantly related bacteria, thereby shuffling resistance genes across taxonomic barriers. Our long-term goal is to limit the rapid spread of multi-drug resistance to important human pathogens, but first a fundamental understanding of the evolution of plasmid host range is essential. Our overall hypothesis is that the host range of plasmids can evolve, much like that of parasites, to become wider or narrower over evolutionary time. To test this hypothesis, we propose the following specific aims: 1) To elucidate evolutionary changes that permit a narrow-host-range plasmid to expand or shift its host range, and 2) To elucidate evolutionary changes that cause host range contraction of a broad-host-range plasmid as a result of long-term association with a single host. To address the first aim, we will evolve the NHR mini-replicon mini-F in four bacterial hosts that show different initial levels of plasmid stability. The DNA sequences of the evolved plasmids will be determined to identify genotypic changes that cause a host range shift or expansion. We postulate that plasmid adaptation resulting in improved stability in one poor host will also improve the stability in other hosts. Under Specific Aim 2, we will examine evolved mutants of the BHR mini-replicon mini-pBP136 that were recently shown to have undergone a shift in host-range. We postulate that the observed shift is due to changes in the interaction of the replication initiation protein TrfA1 with the host helicase. For both Aims mathematical models and statistical analyses will be developed and used to identify the parameters that affect these evolutionary processes. Relevance to public health: This work will unravel the mechanisms of plasmid-host interactions that determine the host range of multi-drug resistance plasmids. This may reveal attractive targets for specific drug therapy in the fight against the alarming spread of drug resistance in human pathogens.