The IrvA-Dependent Pathway: A Link Between Stress Adaptation and Virulence

 描述(申请人提供)：这项拟议的研究旨在研究变形链球菌irvR/A调控系统用来控制众多辅助基因途径以应对环境压力的分子机制。我们以前的研究表明，IRVA是该系统的中央调节因子，是一种核转录调节基因。它的主要调节功能是通过种子与Irva mRNA配对而不是通过其编码的蛋白质的功能来调节的。这种调控是mRNAs功能的新范式。在这个项目中，我们感兴趣的是确定变形链球菌调节Irva表达的机制，Irva作为多效性核转录调节mRNA的作用，以及Irva利用调节核糖核酸酶RNase J2进行基因表达转录后控制的能力。该项目的目标将分三个目标完成。1)为了确定IRVA表达的控制机制，我们将表征调节IRVA基因表达的近端调控因子IrvR的稳定性和功能的蛋白质-蛋白质相互作用。这一机制将测试其在调节生物膜完整性方面的作用 环境压力。2)为了了解IRVA作为多效性核转录调节基因的作用，我们将鉴定IRVA调节子和新发现的IRVA核转录调节所需的RNA伴侣之间的重叠基因集。这些基因将被测试目标mRNA稳定性和种子配对的Irva和伴侣依赖的调节。3)为了研究IRVA利用RNase J2调控基因表达的能力，我们将测试IRVA和RNA伴侣蛋白通过种子配对调控IRVA靶基因RNase J2降解的能力。我们还将确定RNA中指定RNaseJ2切割的识别元件。拟议的研究将提供一些首次对口腔细菌使用的转录后调控机制的机械性见解，并将展示关键途径是如何调节的，以应对环境压力。这将有望为我们理解变形链球菌影响口腔生态的能力增加重要的一层。

 DESCRIPTION (provided by applicant): The proposed research aims to investigate the molecular mechanisms used by the irvR/A regulatory system of Streptococcus mutans to control numerous accessory gene pathways in response to environmental stress. Our previous studies demonstrated that the central regulator of this system irvA is a riboregulatory mRNA. Its principal regulatory function is mediated through seed pairing with irvA mRNA, rather than through the function of its encoded protein. Such regulatory control is a new paradigm for the function of mRNAs. In this project, we are interested to determine the mechanisms used by S. mutans to modulate irvA expression, the role of irvA as a pleiotropic riboregulatory mRNA, and the ability of irvA to exploit the regulatory ribonuclease RNase J2 for the posttranscriptional control of gene expression. The goals of the project will be completed in three Aims. 1) To determine the mechanism controlling irvA expression, we will characterize the protein-protein interactions that modulate the stability and function of the proximal regulator of irvA gene expression, IrvR. This mechanism will be tested for its role in modulating biofilm integrity during environmental stress. 2) To understand the role of irvA as a pleiotropic riboregulatory mRNA, we will identify the overlapping geneset between the irvA regulon and a newly identified RNA chaperone required for irvA riboregulation. These genes will be tested for irvA- and chaperone-dependent regulation of target mRNA stability and seed pairing. 3) To investigate the ability of irvA to exploit RNase J2 for the control of gene expression, we will test irvA and RNA chaperone for their ability to modulate RNase J2 degradation of irvA target mRNAs via seed pairing. We will also determine the recognition elements in RNA that specify cleavage by RNase J2. The proposed studies will provide some of the first mechanistic insights into the posttranscriptional regulatory mechanisms used by oral bacteria and will demonstrate how key pathways are regulated in response to environmental stress. This will hopefully add an important layer to our understanding of S. mutans ability to influence oral ecology.