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。 通过质粒的抗生素抗性基因的接合转移极大地促进了细菌病原体中药物抗性的快速传播，从而降低了人类感染性疾病的各种治疗选择的有效性。虽然一些质粒仅在窄范围的宿主（NHR）中转移和稳定复制，但所谓的宽宿主范围（BHR）质粒在远亲细菌中转移和复制，从而使抗性基因跨越分类障碍。我们的长期目标是限制多重耐药性对重要人类病原体的快速传播，但首先必须对质粒宿主范围的演变有基本的了解。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变得更宽或更窄。为了验证这一假设，我们提出了以下具体目标：1）阐明允许窄宿主范围质粒扩大或转移其宿主范围的进化变化，以及2）阐明导致宽宿主范围质粒由于与单一宿主长期关联而导致宿主范围收缩的进化变化。为了解决第一个目标，我们将在四种细菌宿主中进化NHR迷你复制子迷你F，这些宿主显示出不同的质粒稳定性初始水平。将测定进化质粒的DNA序列，以鉴定导致宿主范围转移或扩增的基因型变化。我们假设，质粒适应导致一个较差宿主的稳定性提高，也会提高其他宿主的稳定性。在特定目标2下，我们将研究BHR微型复制子mini-pBP 136的进化突变体，这些突变体最近被证明在宿主范围内发生了变化。我们推测，观察到的转变是由于在复制起始蛋白TrfA 1与宿主解旋酶的相互作用的变化。对于这两个目标的数学模型和统计分析将开发和使用，以确定影响这些演变过程的参数。与公共卫生的相关性：这项工作将揭示质粒-宿主相互作用的机制，决定了多药耐药质粒的宿主范围。这可能会揭示特定药物治疗的有吸引力的目标，以对抗人类病原体中令人担忧的耐药性蔓延。

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.