Quorum Sensing in Vibrio fischeri: Cell Density Regulation in Global Control of Gene Expression

费氏弧菌中的群体感应：基因表达全局控制中的细胞密度调节

• 批准号: 9808308
• 负责人: Everett Greenberg
• 金额: $ 33万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9808308&HistoricalAwards=false
• 关键词: Quorum; Sensing; Vibrio; fischeri; Cell

It has recently been appreciated that quorum sensing, the ability of a bacterial species to monitor its own population density and activate specific sets of genes at appropriate cell concentrations, is a common trait. This trait is critical to the success of bacteria in adapting to changes in environmental conditions. The classic example of quorum sensing is the luminescent, symbiotic bacterium, Vibrio fischeri. Recent evidence indicates there are two quorum sensing systems in V. fischerii, one that is known to control expression of a set of genes including the luminescence genes and one that presumably controls another set of genes. With the exception of the luminescence genes, the target genes for the two quorum sensing systems remain undefined. The specific aims of this research project are to identify the genes controlled by each of the two quorum sensing systems and to determine whether control of individual genes is direct or indirect. Two main approaches will be taken to identify target genes. I. Wildtype and V. fischeri quorum sensing mutants will be employed to identify proteins expressed at higher levels with or without each of the signal molecules. This approach will involve pulse-chase radiolabeling of cellular proteins. II. Transposon mutagenesis of a V. fischeri quorum sensing null mutant with promoter probe vehicles will be employed to screen for and identify genes that require for their expression the presence or absence of either of the quorum sensing signals. The two main approaches to determine whether quorum sensing control of target genes is direct or indirect will be: I. To measure transcription of target genes in vitro. II. To examine expression of lacZ fusions to target gene promoters in recombinant Escherichia coli. Luminescence gene regulation is the best studied model of quorum sensing in gram negative bacteria. In this model and in other systems it has become clear that the role of quorum sensing in the general regulatory circuits of the cell is complex, yet this has not been investigated systematically. This research will open a new area of study in bacterial cell-to-cell communication.

最近人们认识到，群体感应，细菌物种监测其自身种群密度并在适当的细胞浓度下激活特定基因组的能力，是一种常见的性状。这种特性对于细菌成功适应环境条件的变化至关重要。群体感应的经典例子是发光的共生细菌，费氏弧菌。最近的证据表明，在费氏弧菌中有两个群体感应系统，一个已知控制一组基因（包括发光基因）的表达，另一个可能控制另一组基因。除发光基因外，这两个群体感应系统的靶基因仍不确定。这个研究项目的具体目标是确定由两个群体感应系统控制的基因，并确定单个基因的控制是直接还是间接的。将采取两种主要方法来鉴定靶基因。I.将采用野生型和费氏弧菌群体感应突变体来鉴定在具有或不具有每种信号分子的情况下以更高水平表达的蛋白质。这种方法将涉及细胞蛋白质的脉冲追踪放射性标记。二.用启动子探针载体对费氏弧菌群体感应无效突变体进行转座子诱变，以筛选和鉴定需要存在或不存在任一群体感应信号来表达的基因。确定群体感应对靶基因的控制是直接的还是间接的两种主要方法是：I。体外检测靶基因的转录水平。二.目的研究lacZ融合基因在重组大肠杆菌中的表达。发光基因调控是革兰氏阴性菌群体感应的最佳研究模型。在这个模型和其他系统中，已经清楚的是，群体感应在细胞的一般调节回路中的作用是复杂的，但这还没有被系统地研究。这项研究将开辟细菌细胞间通讯的新研究领域。