Diverted Total Synthesis and Biological Evaluation of Natural Product Biofilm Inhibitors, The Cahuitamycins

项目总结/摘要 多重耐药（MDR）革兰氏阴性菌代表了全球健康危机。传统 抗生素会产生选择压力，滋生抗药性，使我们现有的药物越来越少， 有效靶向细菌毒力因子作为一种替代策略已经引起了人们的兴趣， 有可能解决这个问题。鲍曼不动杆菌依赖多重毒力 建立感染的机制，包括生物膜形成和铁载体介导的铁 采集生物膜是由细胞外基质结合在一起的细菌群落， 附着在表面并显示出增强的抗生素抗性，而铁载体很小- 分子螯合剂，从宿主来源中吸收维持生命的铁。近日一组 被称为cahuitamycins的天然产物的结构特征和确定， 具有抗A.鲍曼不动杆菌。卡惠他霉素含有双齿 在铁载体结构中普遍存在的螯合基序（酚盐-恶唑啉和 异羟肟酸盐）;然而，恶唑啉的开环完全消除了抗生物膜活性。 这在很大程度上意味着这些分子的铁载体样性质与它们的生物活性密切相关。 抗生素活性机制。在此，我们建议研究cahuitamycins，以阐明 这两种临床相关毒力因子之间的生物化学联系。 为此，我们提出了两个相互关联的目标，分别侧重于有机合成， 卡惠他霉素及其类似物的生物学评价， 铁载体-生物膜关系。鲍曼不动杆菌。我们设计了一种合成路线， cahuitamycins是高度收敛的快速生成不同的模拟面板。 将测试衍生物抑制生物膜形成的能力，以及所得结构- 活性关系将用于设计官能化卡惠他霉素探针分子。在 平行，A.将使用铁载体缺陷突变体 文库，共聚焦显微镜表型分析，和转录组学分析， cahuitamycin处理A.鲍曼不动杆菌。使用基于活性的蛋白质分析将使 cahuitamycin靶点鉴定和计算对接将提供深入了解机制 的行动。该提案整合了传染病领域的两个前沿研究领域， 疾病，生物膜形成和铁载体，因此被定位为产生高度影响力的 为今后开发新型抗病毒治疗药物奠定了基础。

Project Summary/Abstract Multidrug resistant (MDR) Gram-negative bacteria represent a global health crisis. Traditional antibiotics create selective pressure and breed resistance, making our current drugs less and less effective. Targeting of bacterial virulence factors has gained interest as an alternative strategy to potentially circumvent this problem. Virulent Acinetobacter baumannii rely on multiple virulence mechanisms to establish infection, including biofilm formation and siderophore-mediated iron acquisition. Biofilms are communities of bacteria bound together by extracellular matrices that adhere to surfaces and display enhanced antibiotic resistance, and siderophores are small- molecule chelators that scavenge life sustaining iron from host sources. Recently, a group of natural products dubbed the cahuitamycins were structurally characterized and determined to have biofilm-inhibitory activity against A. baumannii. The cahuitamycins contain bidentate chelating motifs found ubiquitously in siderophore structures (phenolate-oxazoline and hydroxamate); however, ring-opening of the oxazoline completely abolishes anti-biofilm activity. This heavily implies that the siderophore-like nature of these molecules is closely related to their mechanism of antibiotic activity. Herein, we propose to study the cahuitamycins to shed light on the biochemical connection between these two clinically relevant virulence factors. To this end, we propose two interrelated aims focusing respectively on the organic synthesis of cahuitamycins and analogs thereof, and on the biological evaluation of the cahuitamycins and the siderophore-biofilm relationship in A. baumannii. We have devised a synthetic route to the cahuitamycins that is highly convergent for the rapid generation of diverse analog panels. Derivatives will be tested for their ability to inhibit biofilm-formation, and the resulting structure- activity relationships will be used to design functionalized cahuitamycin probe molecules. In parallel, biofilm formation in A. baumannii will be evaluated using siderophore-deficient mutant libraries, phenotypic profiling by confocal microscopy, and transcriptomic analysis of cahuitamycin-treated A. baumannii. Use of Activity-based Protein Profiling will enable cahuitamycin target identification, and computational docking will provide insight into mechanism of action. This proposal integrates two cutting edge research areas in the field of infectious disease, biofilm formation and siderophores, and as such is positioned to produce highly impactful and foundational work for the future development of novel anti-virulence therapeutics.