Investigating small RNA control of quorum sensing.

描述(由申请人提供)：群体感应是细菌用来评估邻近群落的细胞数量和物种组成的波动的一种化学交流过程。作为对这些参数变化的反应，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，群体感应介导的沟通现在被理解为细菌世界的常态。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，可以使用模式生物发光细菌哈维氏弧菌有效地研究这一过程，哈维氏弧菌是最初发现群体感应的细菌。在哈维氏弧菌群体感应级联的核心是五个非编码的小RNA(SRNAs)，它们直接调节主调控子LuxR的表达，最终控制群体感应基因的表达。这项建议的目标是通过具体研究控制sRNA调控和LuxR指导的群体感应基因表达的因素，来研究细胞如何整合和响应特定的细胞外信号组合。在具体目标1中，我将识别和表征控制这五个sRNA的因素。遗传和生化方法都将被用来评估五个QrR sRNA中的每一个对群体感应的个体贡献。1n具体目标2，我将研究LuxR对群体感应基因的差异调控，以响应细胞外提示。体内表达分析、遗传学和生化将被用来确定LuxR如何根据特定的细胞外线索对基因进行差异控制。我们将检查LuxR控制的基因表达的时机和强度，以了解群体感应调节。与公共健康相关：调节群体感应的分子有可能用作抗微生物药物，针对使用群体感应控制毒力的细菌。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为深入了解细胞内和细胞间信号传递、物种内和物种间通信以及多细胞进化提供新的机制。

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.