Investigating small RNA control of quorum sensing.

描述（由申请人提供）：群体感应是细菌用于评估邻近群落的细胞数量和物种组成波动的化学通讯过程。响应于这些参数的变化，细菌在个体细胞和群体行为模式下的基因表达程序之间切换。以前被认为是少数海洋细菌的异常，群体感应介导的通信现在被认为是细菌世界的常态。研究这一过程对所有微生物学，尤其是工业和临床微生物学至关重要，这可以使用模型生物发光细菌哈维氏弧菌（Vibrio harveyi）进行有效研究，该细菌最初发现了群体感应。在哈维氏弧菌群体感应级联的核心是五个非编码小RNA（sRNA），它们直接调节主调节因子LuxR的表达，LuxR最终控制群体感应基因的表达。该提案的目标是通过专门检查控制sRNA调节和LuxR指导的群体感应基因表达的因素，研究细胞如何整合和响应细胞外信号的特定组合。在具体目标1中，我将确定和描述控制这五种sRNA的因素。遗传和生物化学方法将用于评估五种Qrr sRNA中的每一种对群体感应的个体贡献。在具体目标2中，我将研究群体感应基因的差异调节LuxR响应细胞外线索。体内表达测定、遗传学和生物化学将用于确定LuxR如何响应于特定的细胞外信号差异地控制基因。将检查LuxR控制的基因表达的时间和强度以理解群体感应调节子。公共卫生相关性：调节群体感应的分子具有作为针对利用群体感应来控制毒力的细菌的抗微生物药物的潜在用途。同样，参与这些小分子生产的生物合成酶是新型抗微生物药物设计的潜在目标。除了这项研究的生物技术和医学应用之外，对群体感应的持续研究有望深入了解细胞内和细胞间信号传递，种内和种间通信以及多细胞进化的新机制。

DESCRIPTION (provided by applicant): Quorum sensing is a process of chemical communication that bacteria use to assess fluctuations in the number of cells and species composition of the vicinal community. In response to changes in these parameters, bacteria switch between programs of gene expression underlying individual-cell and group- behavior-modes. Previously assumed to be an anomaly of a few marine bacteria, quorum-sensing-mediated communication is now understood to be the norm in the bacterial world. Investigating this process is vital to all of microbiology, most notably industrial and clinical microbiology, and this can be studied effectively using the model bioluminescent bacterium Vibrio harveyi, the bacterium in which quorum sensing was originally discovered. At the heart of the quorum-sensing cascade in V. harveyi are five non-coding small RNAs (sRNAs) that directly regulate expression of the master regulator, LuxR, which ultimately controls expression of the quorum-sensing genes. The goals of this proposal are to investigate how cells integrate and respond to particular combinations of extracellular cues by specifically examining the factors governing sRNA regulation and LuxR-directed quorum-sensing gene expression. In Specific Aim 1, I will identify and characterize the factors controlling the five sRNAs. Both genetic and biochemical approaches will be used to assess the individual contribution that each of the five Qrr sRNAs makes to quorum sensing. 1n Specific Aim 2, I will investigate differential regulation of quorum-sensing genes by LuxR in response to extracellular cues. In vivo expression assays, genetics, and biochemistry will be used to determine how LuxR differentially controls genes in response to particular extracellular cues. The timing and strength of LuxR- controlled gene expression will be examined to understand the quorum-sensing regulon. PUBLIC HEALTH RELEVANCE: Molecules that modulate quorum sensing have potential use as anti-microbial drugs aimed at bacteria that use quorum sensing to control virulence. Similarly, the biosynthetic enzymes involved in production of these small molecules are potential targets for novel anti-microbial drug design. Beyond the biotechnological and medical applications of this research, a continued study of quorum sensing promises to provide insight into novel mechanisms of intra- and inter-cellular signal transmission, intra- and inter-species communication, and the evolution of multi-cellularity.