Extracytoplasmic function 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压力的调控途径。细菌暴露于干扰细胞壁合成或膜功能的抗生素后，激活了由胞浆外功能(ECF)、Sigma因子和双组分调节系统(TCS)协调的几个大的调节子。这些调节基因包括与抗生素失活或外流有关的基因，与细胞表面重塑以增加耐药性有关的基因，以及与抗生素生产有关的基因。我们将追求三个目标，旨在了解细胞被膜应激引发的全球应激反应。首先，我们将确定一种细菌素的特性，这种细菌素是由枯草杆菌芽胞细胞产生的，它选择性地杀死同一物种的非芽胞细胞。将对细菌素进行结构表征，确定其光谱和活性模式，并探索Sigma-W调节子在防御细菌素活性中的作用。我们还将描述一种依赖于Sigma-W的细菌素，该细菌素是在抗生素暴露时产生的。其次，我们将研究一种对干扰脂质II功能或循环的各种细胞壁活性抗生素有反应的TCS。这个TCS，说谎者，有一个不同寻常的传感器激酶，它是膜内传感蛋白家族的代表，可能与LIAF膜蛋白相互作用。我们将通过说谎者系统来探索信号感知的本质，并定义说谎者规则。第三，我们将使用转录图谱来定义因接触抗生素而引起的应激反应。这项工作将比较与抗生素相关的刺激物和明确的作用机制，以及功能改变的密切相关的结构变体。此外，还将探索枯草杆菌与其他产生抗生素的细菌，包括芽孢杆菌和链霉菌共培养所引起的刺激。最后，我们将确定和描述新的抗生素耐药机制，重点是作为细胞被膜应激反应的一部分而强烈诱导的基因。

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.