Roles for five small RNAs required for quorum sensing in Vibrio harveyi

描述（由申请人提供）：我的首要目标是了解支持集体行为的分子机制。为了探索这一点，我将研究群体感应，模型细菌哈维氏弧菌中的细胞-细胞通信过程：使用群体感应，细菌产生，检测和响应细胞外信号分子（自诱导物），以协调群体范围内的基因表达。在哈维氏弧菌中，在低细胞密度下产生五种调节性小RNA（称为Qrr sRNA），并使编码主群体感应调节因子LuxR的luxR mRNA不稳定。我的目标是了解有五个Qrr sRNA而不是一个sRNA提供了哈维氏弧菌群体感应电路的哪些功能，以及更一般地说，sRNA而不是调节蛋白提供了信号网络的哪些功能。具体而言，我将谈谈以下几点。1)定义单独控制每个qrr sRNA基因的转录因子。五个c/rr sRNA基因启动子是不同的，并且每个gfrrsRNA基因显示出不同的基因表达模式，这表明不同的转录因子调节每个Qrr sRNA基因的表达。我建议确定这些转录因子，并表征其在哈维氏弧菌群体感应反应中的作用。2)识别每个Qrr sRNA独有的mRNA靶标。我将鉴定出由每个哈维氏弧菌Qrr sRNA专门调控的基因，并确定所鉴定的靶标的群体感应功能。3)确定不同的Qrr sRNA对靶mRNA的亲和力如何建立群体感应基因表达的有序程序。我建议，QRR sRNAs结合不同的亲和力的mRNA目标，这会影响各种群体感应响应输出的时间。我将比较Qrr sRNA与已知的哈维氏弧菌mRNA靶标的结合强度，定义Qrr sRNA结合的序列要求，以及改变这些结合特性如何影响群体感应基因表达的时机。 我们的群体感应研究的一个重要的实际方面是，它们正在导致反群体感应疗法的发展，作为传统抗生素的替代品。类似地，对有益细菌（例如生产重要的医疗、农业或工业产品的细菌）中的群体感应的分子理解可以促进群体感应策略的开发和实施，从而改善商业相关天然产品的工业规模生产。

DESCRIPTION (provided by applicant): My overarching goal is to understand the molecular mechanisms underpinning collective behaviors. To explore this, I will study quorum sensing, the process of cell-cell communication in the model bacterium Vibrio harveyi: Using quorum sensing, bacteria produce, detect, and respond to extracellular signal molecules (autoinducers) to coordinate gene expression on a population-wide scale. In V. harveyi, five regulatory small RNAs (called Qrr sRNAs) are produced at low cell densities and act to destabilize the luxR mRNA encoding the master quorum-sensing regulator, LuxR. My goal is to understand what features having five Qrr sRNAs rather than one sRNA provides the V. harveyi quorum-sensing circuit, and, more generally, what features sRNAs rather than regulatory proteins provide to signaling networks. Specifically, I will address the following points. 1) Define the transcription factors that individually control each qrr sRNA gene. The five c/rr sRNA gene promoters are divergent, and each gfrrsRNA gene shows a distinct pattern of gene expression, suggesting that different transcription factors regulate expression of each Qrr sRNA gene. I propose to identify these transcription factors and characterize their roles in the V. harveyi quorum-sensing response. 2) Identify mRNA targets that are exclusive to each Qrr sRNA. I will identify genes regulated exclusively by each of the V. harveyi Qrr sRNAs and determine the quorum-sensing functions of the identified targets. 3) Determine how different Qrr sRNA affinities for target mRNAs establish an ordered program of quorum-sensing gene expression. I propose that the Qrr sRNAs bind with different affinities to mRNA targets and this affects the timing of the various quorum-sensing response outputs. I will compare binding strengths of the Qrr sRNAs with known V. harveyi mRNA targets, define the sequence requirements for Qrr sRNA binding, and how altering those binding properties affects the timing of quorum- sensing gene expression. An important practical aspect of our quorum-sensing investigations is that they are leading to the development of anti-quorum-sensing therapies for use as alternatives to traditional antibiotics. Similarly, a molecular understanding of quorum sensing in beneficial bacteria, such as those that produce medical, agricultural, or industrial products of importance, could facilitate the development and implementation of pro- quorum-sensing strategies that improve industrial-scale production of commercially relevant natural products.