RUI: Acid Signals and Bacterial Drug Efflux Systems

植物产生与阿司匹林相关的芳香酸，可能会限制或逆转土壤环境和肠道微生物组中的细菌耐药性。暴露于水杨酸选择大肠杆菌菌株已失去多药耐药性。适应性成本增加的机制尚不清楚，但可能涉及细菌细胞质子动力的耗尽，质子动力是为药物外排泵提供动力的能源。在这个项目中，本科研究人员将剖析有机酸如何逆转多药耐药性的机制。“第一年第一”计划将每年招收8名新生（三年24名）进行研究，由首席研究员和一个高级本科生团队监督。该招聘计划旨在吸引来自经济背景有限的学生，并鼓励他们从事STEM的研究事业。大肠杆菌在水杨酸盐或茉莉酸盐存在下产生适合度损失。质子动力的作用将通过使用药物泵阻断剂来测试，这可能会降低质子驱动泵的适应性成本。特定的酸阴离子的作用将通过比较水杨酸盐和茉莉酸盐与它们的甲酯的影响进行测试。耐药逆转的假说将扩展到大肠杆菌以外。通过与植物、土壤和人类微生物组相关的细菌物种的水杨酸盐依赖性实验进化，包括植物寄生荧光假单胞菌、土壤细菌枯草芽孢杆菌以及土壤和肠道发酵菌粪肠球菌，来鉴定大肠杆菌。对乙锭标记的细胞进行流式细胞仪分选将鉴定失去多药泵的突变体。水杨酸进化克隆的基因组和转录组将揭示每个物种独特的调控途径的重新布线。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Plants produce aromatic acids related to aspirin that may limit or reverse bacterial drug resistance within the soil environment and gut microbiome. Exposure to salicylic acid selects for Escherichia coli strains that have lost multidrug resistance. The mechanism of the increased fitness cost is unclear, but may involve depletion of the bacterial cell's proton motive force, the energy source that powers drug efflux pumps. In this project, undergraduate researchers will dissect the mechanism of how organic acids reverse multidrug resistance. The "First-years First" program will recruit eight incoming undergraduate students annually (24 over three years) to conduct research, with supervision by the principal investigator and a team of advanced undergraduates. The recruitment program is designed to attract students from economically limited backgrounds and encourage them to pursue research careers in STEM.Competition assays by flow cytometry will reveal which drug-efflux genes of E. coli incur fitness cost in the presence of salicylate or jasmonate. The role of proton motive force will be tested by using drug pump blockers, which may decrease the fitness cost of the proton-driven pumps. The role of specific acid anions will be tested by comparing the effects of salicylate and jasmonate with that of their methyl esters. The hypothesis of drug resistance reversal will be extended beyond E. coli by salicylate-dependent experimental evolution of bacterial species relevant to plant, soil and human microbiomes, including the plant commensal Pseudomonas fluorescens, the soil bacterium Bacillus subtilis, and the soil and gut fermenter Enterococcus faecalis. FACS sorting of ethidium-labeled cells will identify mutants that lose multidrug pumps. Genomes and transcriptomes of salicylate-evolved clones will reveal the rewiring of regulatory pathways unique to each species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.