Synthetic Ligands for Modulating Bacterial Communication

项目摘要/摘要 群体感应在细菌中广泛存在，并在它们与细菌的相互作用中起着关键作用。 真核宿主。这种细胞间信号机制是基于小分子配体和它们的 同源蛋白受体，并允许细菌评估其当地的种群密度和功能 作为一个整体。拟议研究的长期目标是设计、合成和 表征能够截取天然QS信号用作工具的非天然小分子 剖析QS在细菌种群和细菌-宿主联合中的无数作用。这个 这种化学探针的潜在影响是巨大的，范围从基础研究中的应用 到治疗和生物材料的开发。因为许多最臭名昭著的人类病原体使用 QS激活毒力途径，这些途径是急性和慢性感染的根源，包括生物膜 QS拮抗剂作为一种新型抗菌剂的应用前景看好 策略。这种“抗毒力”药剂与目前的抗生素不同，因为它们针对的是传染性 与生长相反，代表着治疗细菌介导性疾病的范式转变。 革兰氏阴性细菌中的QS是迄今为止最具特点的，也是本项目的重点。这些 QS电路基于N-酰基L-高丝氨酸内酯信号和LuxR型转录 AHL与其靶向LuxR型受体结合触发QS控制基因 在高细胞密度下表达。在早期的工作中，我们研究了LuxR型受体的结构 配体结合位点，设计了能够靶向这些位点的非天然配体，并开发了 通往这些化合物文库的有效合成途径。模型中的图书馆评价 细菌菌株发现了几种最有效的LuxR型合成拮抗剂和激动剂 QS报告到目前为止。这些结果验证了我们的整体研究策略。 我们现在的目标是开发能够拦截LuxR型QS的新的小分子支架 随着效力和稳定性的提高，确定这些化合物发挥作用的机制 它们的QS调节活性，并检测它们在野生型中减弱QS表型的能力 人类病原体。在赠款期间，这些目标将通过三个具体目标来实现。 它们是：(1)新型合成QS拮抗剂和激动剂的设计和结构优化，(2) 合成配体对LuxR型受体拮抗和激化作用的机理分析 QS拮抗剂的细胞毒力测定及抗性发展研究。结果是 本文提出的跨学科研究将提供对 QS的机制，最终可以为下一步的发展提供一种途径。 针对细菌感染的世代、抗毒力治疗。

PROJECT SUMMARY / ABSTRACT Quorum sensing (QS) is widespread in bacteria and plays a pivotal role in their interactions with eukaryotic hosts. This intercellular signaling mechanism is based on small molecule ligands and their cognate protein receptors, and allows bacteria to assess their local population densities and function as a group. The long-term objective of the proposed research is to design, synthesize, and characterize non-native small molecules capable of intercepting native QS signals for use as tools to dissect the myriad roles of QS in bacterial populations and in bacteria-host associations. The potential impact of such chemical probes is enormous, and ranges from applications in basic research to therapeutic and biomaterials development. As many of the most notorious human pathogens use QS to activate virulence pathways that are the origin of acute and chronic infections, including biofilm formation, the application of QS antagonists holds significant promise as a novel antimicrobial strategy. Such "anti-virulence" agents differ from current antibiotics because they target infectivity as opposed to growth, and represent a paradigm shift for the treatment of bacteria-mediated disease. QS in Gram-negative bacteria is the best characterized to date and the focus of this project. These QS circuits are based on N-acyl L-homoserine lactone (AHL) signals and LuxR-type transcription factors, and binding of the AHL to its target LuxR-type receptor triggers QS-controlled gene expression at high cell densities. In earlier work, we studied the structures of LuxR-type receptor ligand-binding sites, designed non-native ligands capable of targeting these sites, and developed efficient synthetic routes to libraries of these compounds. Evaluation of the libraries in model bacterial strains revealed several of the most potent synthetic antagonists and agonists of LuxR-type QS reported to date. These results validate our overall research strategy. Our intent now is to develop new small molecules scaffolds capable of intercepting LuxR-type QS with improved potencies and stabilities, determine the mechanisms by which these compounds exert their QS modulatory activities, and examine their ability to attenuate QS phenotypes in wild-type human pathogens. During the grant period, these objectives will be pursued in three Specific Aims. These are: (1) Design and Structural Optimization of New Synthetic QS Antagonists and Agonists, (2) Mechanistic Analysis of LuxR-type Receptor Antagonism and Agonism by Synthetic Ligands, and (3) Cell-Based Virulence Assays and Studies of Resistance Development to QS Antagonists. The results of the interdisciplinary research proposed herein will provide fundamental insights into the mechanisms of QS and ultimately could provide an approach for the development of next- generation, anti-virulence treatments for bacterial infection.