Collaborative research: Short-circuiting in bacterial quorum sensing

合作研究：细菌群体感应的短路

• 批准号: 1158531
• 负责人: Jack Dockery
• 金额: $ 5.28万
• 依托单位: Montana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1158531&HistoricalAwards=false
• 关键词: Collaborative; research; Short; circuiting; bacterial

Intellectual meritBacterial cell-cell communication, also termed quorum sensing (QS) is a wide-spread process that coordinates multicellular behaviors such as virulence, biofilm formation, and nutrient acquisition in response to cell density, population structure and environmental viscosity. There has been an explosion in research directed at understanding the molecular mechanisms of QS, but there is a paucity of information on the ecophysiological implications and on the emergent properties of QS regulatory networks. The current project addresses this need by combining genetics, physiology, and systems biology in understanding QS in the model bacterium Pseudomonas aeruginosa. This bacterium communicates via diffusible acyl-homoserine lactone signals to control the expression of hundreds of genes. The particular focus is on two central properties of the P. aeruginosa QS network, antiactivation and co-regulation. Antiactivation, initially characterized in the plant pathogen Agrobacterium tumefaciens, inhibits the activity of cognate QS receptors through direct protein-protein interaction. Co-regulation permits the integration of other environmental signals into the quorum response. A key feature here is the starvation-dependent transcription of the main P. aeruginosa QS receptor, LasR. Because several QS-controlled products are costly extracellular enzymes involved in nutrient acquisition, co-regulation by starvation appears ecologically worthwhile. The roles of antiactivation and lasR regulation in modulating the quorum response and in preventing "short-circuiting" will be investigated. Short-circuiting, or self-induction, is a major unanswered question in bacterial QS: How is it that diffusible quorum-signals do not immediately bind to their cognate receptors in the same cell in which they are produced and activate gene expression independent of cell density? Based on recent modeling data, the PIs hypothesize that antiactivation and lasR regulation help prevent short-circuiting, and that the tight environmental control of lasR expression is key in modulating quorum responses that are either short-circuited, triggered by cell density, or triggered by starvation. The specific aims of the project, which integrate experimentation and computational modeling, are therefore to (1) directly observe short-circuiting of QS target gene expression in antiactivator-deficient and lasR overexpressing cells, (2) investigate the growth-rate dependence of QS gene induction and short-circuiting in wild-type cells, and (3) develop a model of the las QS network that, in addition to antiactivation and co-regulation, incorporates and evaluates key properties such as receptor-QS signal interaction, receptor dimerization, autoregulation, and active efflux. Broader impactsResearch. The research conducted by the PIs over the last decade, funded in part by NSF, has established P. aeruginosa QS as a global regulatory network, has provided insight into the function of the central QS regulator LasR, has demonstrated that QS is a cooperative behavior subject to social conflict, and has resulted in the first computational model of P. aeruginosa QS. The current project will incorporate and extend these findings to understand the basic design features of a QS network, including antiactivation and the integration of environmental cues. The work will broadly benefit and will find application in synthetic biology and biotechnology for the design of novel genetic response circuits. Education. The described project provides excellent educational opportunities for students. The PIs have and will continue to train graduate and undergraduate students. Dr. Schuster will also provide educational opportunities for high-school students through the Apprenticeship for Science and Engineering, an established summer internship program at Oregon State University. Many of the proposed experiments are conceptually and technically straight-forward and are particularly well suited for the engagement of high-school and undergraduate students in the scientific process.

细菌细胞间通讯，也称为群体感应（quorum sensing，QS），是一个广泛存在的过程，它协调多细胞行为，如毒力，生物膜形成和营养物质获取，以响应细胞密度，种群结构和环境粘度。 有一个爆炸性的研究，旨在了解QS的分子机制，但有一个缺乏的信息的生理生态的影响和QS监管网络的新兴属性。目前的项目通过结合遗传学、生理学和系统生物学来理解模式细菌铜绿假单胞菌中的QS来解决这一需求。这种细菌通过可扩散的酰基-高丝氨酸内酯信号来控制数百个基因的表达。特别关注的是铜绿假单胞菌QS网络的两个中心特性，抗激活和协同调节。抗激活作用最初在植物病原体根癌农杆菌中表征，其通过直接的蛋白质-蛋白质相互作用抑制同源QS受体的活性。 协同调节允许将其他环境信号整合到群体响应中。 这里的一个关键特征是主要铜绿假单胞菌QS受体LasR的饥饿依赖性转录。 由于几个QS控制的产品是昂贵的胞外酶参与营养物质的获取，共同调节饥饿出现生态价值。 将研究抗激活和lasR调节在调节群体反应和防止“短路”中的作用。 短路或自诱导是细菌QS中一个主要的未回答的问题： 为什么可扩散的群体信号不会立即与产生它们的同一细胞中的同源受体结合，并激活基因表达而不依赖于细胞密度？ 基于最近的建模数据，PI假设抗激活和lasR调节有助于防止短路，并且lasR表达的严格环境控制是调节由细胞密度触发的短路或由饥饿触发的群体反应的关键。因此，该项目的具体目标是整合实验和计算建模，（1）直接观察抗激活因子缺陷和lasR过表达细胞中QS靶基因表达的短路，（2）研究野生型细胞中QS基因诱导和短路的生长速率依赖性，以及（3）开发las QS网络模型，除了抗激活和共调节，还包括并评估了关键特性，如受体-QS信号相互作用、受体二聚化、自动调节和主动外排。更广泛的影响研究。在过去十年中，由美国国家科学基金会（NSF）部分资助的PI进行的研究已经将铜绿假单胞菌QS建立为全球监管网络，深入了解了中央QS监管机构LasR的功能，证明了QS是一种受社会冲突影响的合作行为，并产生了铜绿假单胞菌QS的第一个计算模型。目前的项目将纳入并扩展这些发现，以了解QS网络的基本设计特征，包括抗激活和环境线索的整合。这项工作将广泛受益，并将在合成生物学和生物技术中找到新的遗传反应电路设计的应用。 教育所述项目为学生提供了极好的教育机会。 PI已经并将继续培训研究生和本科生。 舒斯特博士还将通过科学与工程学徒项目为高中生提供教育机会，这是俄勒冈州州立大学的一个既定暑期实习项目。许多拟议的实验在概念上和技术上都是直截了当的，特别适合高中和本科学生参与科学过程。