Intra- and inter species cell-cell communication in Vibrio cholerae

描述（由申请人提供）：人类病原体霍乱弧菌使用群体感应，包括被称为自诱导剂的化学信号分子的产生、释放和随后的检测，以调节毒力基因表达，以响应细胞种群密度和物种复杂性的变化。目前已知两种霍乱弧菌自动诱导检测系统，一种用于种内传播，另一种用于种间传播。该应用程序的长期目标是了解该细菌种内和种间群体感应信号的分子机制。每个细胞外自诱导剂编码的独特信息在内部被翻译成磷酸化反应调节因子LuxO的离散水平，这决定了霍乱弧菌群体感应系统的最终输出。由于天冬氨酸磷酸酯的不稳定性，磷酸化细菌反应调节因子的体内水平从未被直接测定过。为了理解霍乱弧菌群体感应电路中的信号-响应输入-输出关系，我的第一个目标是开发霍乱弧菌细胞中磷酸化- luxo水平定量测量的方法。将两种不同的自动诱导器中包含的信息整合到一个单一的调节网络中，可以使霍乱弧菌群体感应系统发挥巧合探测器的作用。或者，该电路可以通过两种自诱导剂的任何或所有组合促进不同的基因调控。我的第二个目标是通过研究每种自诱导剂对特定靶基因表达的影响来区分这两种可能性。将对选定的靶基因的时间表达动态进行测量，以确定这些自诱导剂是否一起起作用，或者是否存在一个有序的基因表达层次，以响应不同的自诱导剂组合。这些研究的结果将充分定义群体感应信号电路中每个调节元件的作用。该应用程序的第三个目的是确定霍乱弧菌和其他细菌物种之间存在的新的化学信号通信途径。物种间的交流可能使霍乱弧菌能够在复杂的环境中适应、竞争和生存，比如受污染的水和存在许多其他细菌物种的人类肠道。这种物种间交流途径的组成部分将被识别和表征。总之，这些研究将为霍乱弧菌种内和种间通讯网络的分子结构提供见解。实际上，这项工作的结果可能会导致反群体感应疗法的发展，作为传统抗生素的替代品。

DESCRIPTION (provided by applicant): The human pathogen Vibrio cholerae uses quorum sensing which involves the production, release, and subsequent detection of chemical signaling molecules called autoinducers, to regulate virulence gene expression in response to changes in cell-population density and species complexity. Two V. cholerae autoinducer-detection systems, one for intra-species and one for inter-species communication, are currently known. The long term goal of this application is to understand the molecular mechanisms underlying intra-species and inter-species quorum-sensing signaling in this bacterium. The unique information encoded in each extracellular autoinducer is translated internally into discrete levels of the phosphorylated response regulator LuxO, which determines the final output of the V. cholerae quorum-sensing system. Due to the instability of aspartyl phosphates, in vivo levels of phosphorylated bacterial response regulators have never been directly determined. To understand the signal-response input-output relationship in the V. cholerae quorum-sensing circuit, my first aim is to develop methodology for the quantitative measurement of phospho-LuxO levels in V. cholerae cells. Integration of the information contained in the two different autoinducers into a single regulatory network could allow the V. cholerae quorum-sensing system to function as a coincidence detector. Alternatively, this circuit may facilitate distinct gene regulation by any or all combinations of the two autoinducers. My second aim is focused on distinguishing between these two possibilities by investigating the effect of each autoinducer on specific target gene expression. Measurement of the temporal expression dynamics of selected target genes will be performed to establish whether the autoinducers function together or if there is an ordered gene expression hierarchy in response to different autoinducer combinations. Results from these studies will fully define the role of each regulatory element in the quorum-sensing signaling circuit. The third aim of this application is to identify novel chemical signal communication pathways that exist between V. cholerae and other bacterial species. Inter-species communication likely enables V. cholerae to adapt, compete, and survive in complex environments such as contaminated water and the human intestine where many other bacterial species are present. The components involved in such inter-species communication pathways will be identified and characterized. Together, these studies will provide insight into the molecular architecture of V. cholerae intra- and inter-species communication networks. Practically, results from this work could lead to the development of anti-quorum-sensing therapies for use as alternatives to traditional antibiotics.