Novel Two Component Regulation of Quorum Sensing & Secondary Metabolite Production in Bacteria

澳大利亚PIERSON IIIPROPOSAL # NSF 0545804标题：细菌群体感应和次级代谢产物产生的新型双组分调节宿主相关细菌，无论是致病的还是有益的，都能在由宿主及其相关微生物群落决定的环境中生存。宿主相关细菌利用感觉网络来调节建立和维持宿主相关性所需的次级代谢产物的表达。吩嗪类化合物是一类重要的次生代谢产物，在植物病害防治中起重要作用，在人类病原菌铜绿假单胞菌的毒力中也起重要作用。在这两种细菌中，吩嗪部分由双组分群体感应（QS）系统调节（例如，吩嗪仅在细菌种群达到足够的密度或群体后表达）。一种新的双组分调节系统（RpeA/RpeB）被确定在这两种细菌，突变时，消除了对QS的要求，并导致吩嗪生产过剩。这一发现特别有趣，因为绕过QS控制的（RpeA/RpeB）系统中的突变可能会严重限制旨在通过干扰QS调节来降低细菌毒力和感染的新抗生素治疗的有效性。该提案概述了一种系统的方法来表征新的负双组分调节系统（RpeA/RpeB）及其与营养传感和QS的联系。这两种感觉系统之间的联系将使用全局基因表达分析在金霉素假单胞菌和铜绿假单胞菌中确定。还将确定这种双组分系统的损失对细菌与宿主结合时的生态适合度的影响。了解这种双组分系统的损失如何绕过QS法规，将为成功控制植物病害或阻断人类疾病建立所需的次生代谢产物生产提供深入了解。拟议研究的多学科性质将i）为本科生和研究生提供培训机会，并将信息和技术整合到讲座，实验室练习和现有的本科生和研究生研究机会中，ii）通过美国植物病理学会教育中心进行推广。

ABSTRACTLELAND S. PIERSON IIIPROPOSAL # NSF 0545804TITLE: Novel Two-Component Regulation of Quorum Sensing and Secondary Metabolite Production in BacteriaHost-associated bacteria, whether pathogenic or beneficial, survive in an environment determined by the host and its associated microbial community. Host-associated bacteria use sensory networks to regulate the expression of secondary metabolites needed to establish and maintain host associations. Phenazines are secondary metabolites important in plant disease control by Pseudomonas aureofaciens and also in virulence by the human pathogen P. aeruginosa. In both bacteria, phenazines are regulated, in part, by a two-component quorum sensing (QS) system (e.g. phenazines are expressed only after bacterial populations reach a sufficient density or quorum). A novel two-component regulatory system (RpeA/RpeB) was identified in both bacteria that, when mutated, removed the requirement for QS and resulted in overproduction of phenazines. This finding is particularly interesting because mutations in the (RpeA/RpeB) system, which bypasses QS control, could severely limit the effectiveness of new antibiotic therapies aimed at reducing bacterial virulence and infection by interfering with QS regulation. This proposal outlines a systematic approach to characterize the novel negative two component regulatory system (RpeA/RpeB) and its linkage to nutritional sensing and QS. The linkage between these two sensory systems will be determined in both P. aureofaciens and P. aeruginosa using global gene expression analysis. The effect of loss of this two-component system on the ecological fitness of the bacteria when associated with hosts also will be determined. Understanding how loss of this two-component system bypasses QS regulation will provide insights into strategies for enhancing secondary metabolite production essential for successful plant disease control or for blocking secondary metabolite production required for human disease establishment. The multidisciplinary nature of the proposed research will i) provide training opportunities for undergraduate and graduate students and integration of information and technologies into lectures, laboratory exercises and existing undergraduate and graduate research opportunities, ii) outreach via the American Phytopathological Society Education Center.