Inhibition of the Agrobacterium tumefaciens Quorum Sensor by the TraM Anti-Activator

TraM 抗激活剂对根癌农杆菌群体传感器的抑制

• 批准号: 9974863
• 负责人: William Fuqua
• 金额: $ 31.67万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9974863&HistoricalAwards=false
• 关键词: Inhibition; Agrobacterium; tumefaciens; Quorum; Sensor

Many species of bacteria employ signaling mechanisms to monitor their own population density and respond by altering physiological and developmental pathways. This process usually entails the release of a soluble pheromone, the local concentration of which provides a measure of cell density. Release and perception of the signaling molecule has been termed quorum sensing. Quorum sensing in a number of gram-negative bacteria is facilitated by production of acylated homoserine lactones (acyl HSL). Agrobacterium tumefaciens, the causative agent of plant crown gall neoplasia, utilizes the acyl HSL N-3-(oxooctanoyl) homoserine lactone to regulate the conjugal dissemination of its primary virulence factor, the Ti (tumor-inducing) plasmid, to other bacteria in the rhizosphere. The current proposal focuses on examination of a unique and essential inhibitory component of the A. tumefaciens acyl HSL regulatory pathway. For most acyl HSL-type quorum sensors, a pheromone synthase and a receptor protein that also serves as a transcriptional activator are sufficient to impart cell-density-dependent gene expression. However, A. tumefaciens requires a third component, a regulator protein called TraM, to facilitate quorum sensing. The hypothesis is that TraM forms a noncovalent complex with the acyl HSL receptor, TraR, which prevents the transcriptional activator from binding DNA. The overall goal of this research is to dissect the interaction between TraM and TraR and to understand how this interaction modulates the activity of TraR. Biochemical analysis will be employed to examine the inhibitory complex and to determine the effect of inhibition on the activity of TraM and TraR in the presence of acyl HSL. Mutant TraR and TraM proteins that exhibit altered regulatory phenotypes will beisolated and biochemically analyzed to correlate in vitro and in vivo activities. Additional studies will assess the effects of regulation of traM expression and pool size. This research will not only elucidate a unique aspect of acyl HSL quorum sensing in the important model pathogen A. tumefaciens, but will also contribute to the understanding of cell-cell communication in other species of bacteria.

许多种类的细菌利用信号传导机制来监测它们自己的种群密度，并通过改变生理和发育途径来做出反应。这个过程通常需要释放一种可溶性信息素，其局部浓度提供了细胞密度的测量。信号分子的释放和感知被称为群体感应。在许多革兰氏阴性细菌中，群体感应通过产生酰化高丝氨酸内酯（酰基HSL）来促进。根癌农杆菌是植物冠瘿瘤形成的病原体，其利用酰基HSL N-3-（氧代辛酰基）高丝氨酸内酯来调节其主要毒力因子Ti（肿瘤诱导）质粒向根际中的其它细菌的接合传播。目前的建议集中在检查一个独特的和必要的抑制成分的A。根癌农杆菌酰基HSL调控途径。 对于大多数酰基HSL型群体传感器，信息素合酶和受体蛋白，也作为转录激活剂是足以赋予细胞密度依赖性基因表达。然而，A.根癌农杆菌需要第三种成分，一种叫做TraM的调节蛋白来促进群体感应。 假设TraM与酰基HSL受体TraR形成非共价复合物，其阻止转录激活因子结合DNA。 本研究的总体目标是剖析TraM和TraR之间的相互作用，并了解这种相互作用如何调节TraR的活性。 将采用生物化学分析来检查抑制复合物并确定在酰基HSL存在下抑制对TraM和TraR活性的影响。 突变的TraR和TraM蛋白表现出改变的调节表型将被分离和生化分析，以关联在体外和体内活动。 进一步的研究将评估调节traM表达和池大小的影响。 本研究不仅将阐明重要模式病原体A中酰基HSL群体感应的一个独特方面。tumefaciens，但也将有助于了解其他细菌物种的细胞间通讯。