ECF sigma factors & cell envelope stress in B. subtilis

描述（由申请人提供）：我们的长期目标是使用枯草芽孢杆菌作为模型系统来定义响应细胞包膜应激的调控途径。细菌暴露于干扰细胞壁合成或膜功能的抗生素中，激活由胞质外功能（ECF） sigma因子和双组分调节系统（TCS）协调的几个大调控。这些调控包括参与抗生素失活或外排的基因，参与细胞表面重塑以增加耐药性的基因，以及参与抗生素生产的基因。我们将追求三个目标，旨在了解由细胞包膜应力引起的全局应激反应。首先，我们将描述一种由产孢枯草芽孢杆菌细胞产生的细菌素，这种细菌素选择性地杀死同一物种的非产孢细胞。我们将对这种细菌素进行结构表征，确定其光谱和活性模式，并探索Sigma-W调控在抵抗细菌素活性中的作用。我们还将描述一种西格玛- w依赖性细菌素，它是在抗生素暴露的反应中产生的。其次，我们将研究一种对多种细胞壁活性抗生素有反应的TCS，这些抗生素会干扰脂质II的功能或循环。这个TCS， LiaRS，有一个不寻常的传感激酶，是膜内传感激酶家族的代表，可能与LiaF膜蛋白相互作用。我们将探讨说谎者系统信号感知的本质，并定义说谎者规则。第三，我们将使用转录谱来定义暴露于抗生素引起的应激反应。这项工作将比较与抗生素相关的刺激物，这些刺激物具有明确的作用机制和密切相关的结构变异，具有改变的功能。此外，还将探讨枯草芽孢杆菌与其他产生抗生素的细菌（包括芽胞杆菌和链霉菌）共培养引起的刺激。最后，我们将识别和表征新的抗生素耐药机制，重点关注作为细胞包膜应激反应一部分被强烈诱导的基因。

DESCRIPTION (provided by applicant): Our long term goal is to define the regulatory pathways that respond to cell envelope stress using Bacillus subtilis as a model system. Exposure of bacteria to antibiotics that interfere with cell wall synthesis or membrane function activates several large regulons coordinated by extracytoplasmic function (ECF) sigma factors and two-component regulatory systems (TCS). These regulons include genes involved in the inactivation or efflux of antibiotics, in remodeling of the cell surface to increase resistance, and in the production of antibiotics. We will pursue three aims directed at understanding the global stress responses elicited by cell envelope stress. First, we will characterize a bacteriocin produced by sporulating B. subtilis cells that selectively kills non-sporulating cells of the same species. This bacteriocin will be structurally characterized, its spectrum and mode of activity defined, and the role of the Sigma-W regulon in defending against bacteriocin activity will be explored. We will also characterize a Sigma-W dependent bacteriocin that is produced in response to antibiotic exposure. Second, we will investigate a TCS that responds to a variety of cell wall active antibiotics that interfere with lipid II function or cycling. This TCS, LiaRS, has an unusual sensor kinase that is representative of a family of intramembrane-sensing kinases and may interact with the LiaF membrane proten. We will explore the nature of signal-sensing by the LiaRS system and define the LiaR regulon. Third, we will use transcriptional profiling to define the stress responses elicited by exposure to antibiotics. This work will compare the stimulons associated with antibiotics with well defined mechanisms of action and closely related structural variants with altered function. In addition, the stimulons elicited by co-culture of B. subtilis with other antibiotic producing bacteria, including Bacilli and Streptomycetes, will be explored. Finally, we will identify and characterize novel antibiotic resistance mechanisms focusing on genes that are strongly induced as part of the cell envelope stress responses.