Regulation of the Heat Shock Response in E. Coli

大肠杆菌热激反应的调节

• 批准号: 8019071
• 负责人: CAROL Anne GROSS
• 金额: $ 43.43万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8019071
• 关键词: Accounting; Address; Animal Model; Antibiotics; Bacteria; Binding; Biomass; Biotechnology; C-terminal; Cells; Cleaved cell; Collaborations; Communication; Coupled; Coupling; Cytoplasmic Protein; DNA-Directed RNA Polymerase; Data; Disease; Drug Metabolic Detoxication; Ecosystem; Environment; Escherichia coli; Excision; Feedback; Funding; Future; Genomics; Goals; Grant; Growth; Guanosine Triphosphate Phosphohydrolases; Health; Heat-Shock Response; Homeostasis; In Vitro; Length; Life; Mediating; Membrane; Membrane Proteins; Messenger RNA; Microbe; Minerals; Modeling; Molecular Chaperones; Organism; Pathogenesis; Pathway interactions; Peptide Hydrolases; Peptides; Peripheral; Play; Process; Production; Progress Reports; Prokaryotic Cells; Property; Proteins; Publishing; Reaction; Recycling; Regulation; Regulatory Pathway; Regulon; Role; Signal Recognition Particle; Signal Transduction; Signal Transduction Pathway; Stress; System; Testing; Time; Virulence; Work; arm; base; biological adaptation to stress; cell envelope; combat; design; in vivo; periplasm; porin; prevent; receptor; reconstitution; research study; response; thermal stress

DESCRIPTION (provided by applicant): Effective mechanisms to maintain cellular homeostasis and combat stress are vital to all living organisms. We study two issues fundamental to all living cells: how to construct an effective response to thermal stress (the ?32-directed heat shock response; HSR), and how to maintain homeostasis in discrete compartments of the cell (the ?E-directed envelope stress response). Our future work will address 3 critical questions: 1) How is homeostatic feedback control of ?32 accomplished? The activity of the HSR is coupled to cellular folding state by a homeostatic feedback control system. Surprisingly, our new studies implicate FtsY, the receptor (SR) for the Signal Recognition Particle (SRP), which is required for insertion of proteins into the inner membrane in this pathway. We will examine the role of SR/SRP proteins in feedback regulation, and test the provocative hypothesis that membrane localization of ?32 plays a regulatory role in this process; possibly by amplifying the length of time ?32 is unavailable for binding RNA polymerase. If these studies implicate the SR/SRP machine in cellular control, they will also provide the basis for a paradigm changing view of these universally conserved GTPases. 2) How are envelope stress signals integrated to activate the ?E response? Envelope stress controls the rate of degradation of RseA, the membrane spanning antisigma factor that negatively regulates ?E, thereby coupling ?E activity to status of the cell envelope. Previously, we thought that this pathway was activated simply by unassembled porins but our recent work suggests that two additional signals are required for activation. We will identify these signals, determine the relationship between the three signals, and reconstitute this regulatory pathway in vitro. These studies will provide critical understanding of how the two cellular compartments communicate. 3) What is the impact of sRNAs in the ?E (and ?32) mediated stress responses? Our recent work and that of others indicates that a major aspect of the ?E response is production of sRNAs that downregulate outer membrane porins. We will identify the remaining ?E sRNAs and test the hypothesis that they function to provide overall surveillance of outer membrane porin content and critical control of the properties of the stress response. Additionally, our preliminary evidence indicates that an sRNA controls DnaK, a regulator of ?32. Therefore, we will also identify ?32-controlled sRNAs and screen for those with regulatory roles. PUBLIC HEALTH RELEVANCE: Project relevance Microbes account for fully half of the world's biomass and are of immense importance to life on earth, for reasons as diverse as performing mineral recycling in our ecosystem, making products of important for biotechnology and detoxification of the environment, and causing disease. In the last decade, the genomic sequences of 444 bacteria have been published and hundreds more are in progress. It is impossible to study all of these bacteria, but we can perform an intensive study of selected bacteria, as the paradigms we develop are widely applicable to all bacteria. We study the regulation and function of two critical responses to stress, in the model organism E. coli, where cutting edge studies are possible. These responses are highly conserved, and both have been implicated in pathogenesis in related organisms. Moreover, one of the strategies we are defining is proving to be a paradigm for responses that orchestrate production of antibiotics, virulence and agents important in environmental cleanup. Finally, our studies may uncover new targets for antibiotics.

描述（由申请人提供）：维持细胞稳态和对抗压力的有效机制对所有生物体都至关重要。我们研究所有活细胞的两个基本问题：如何构建对热应激的有效响应（?32 定向热休克响应；HSR），以及如何维持细胞离散区室的稳态（?E 定向包络应力响应）。我们未来的工作将解决 3 个关键问题：1）如何实现 ?32 的稳态反馈控制？ HSR 的活动通过稳态反馈控制系统与细胞折叠状态耦合。令人惊讶的是，我们的新研究涉及信号识别颗粒 (SRP) 的受体 (SR) FtsY，该受体是将蛋白质插入该途径的内膜所必需的。我们将研究 SR/SRP 蛋白在反馈调节中的作用，并测试 ?32 的膜定位在此过程中发挥调节作用的假设；可能是通过放大无法结合RNA聚合酶的时间长度？32。如果这些研究表明 SR/SRP 机器参与细胞控制，它们也将为这些普遍保守的 GTP 酶的范式改变观点提供基础。 2) 如何整合包络应力信号来激活 ?E 响应？包膜应激控制 RseA 的降解速率，RseA 是一种跨膜抗西格玛因子，负向调节 ?E，从而将 ?E 活性与细胞包膜的状态耦合起来。以前，我们认为该途径仅由未组装的孔蛋白激活，但我们最近的工作表明激活需要两个额外的信号。我们将识别这些信号，确定这三个信号之间的关系，并在体外重建这个调节途径。这些研究将为两个细胞区室如何通信提供重要的理解。 3) sRNA 在 ?E（和 ?32）介导的应激反应中有何影响？我们和其他人最近的工作表明，?E 反应的一个主要方面是产生下调外膜孔蛋白的 sRNA。我们将鉴定剩余的 ?E sRNA 并检验以下假设：它们的功能是对外膜孔蛋白含量进行全面监测，并对应激反应的特性进行关键控制。此外，我们的初步证据表明 sRNA 控制 DnaK，即 ?32 的调节因子。因此，我们还将鉴定β32控制的sRNA并筛选那些具有调节作用的sRNA。公共卫生相关性：项目相关性 微生物占世界生物量的一半，对地球上的生命极其重要，其原因多种多样，包括在我们的生态系统中进行矿物质回收、制造对生物技术和环境解毒至关重要的产品以及引起疾病。在过去的十年中，444 种细菌的基因组序列已经发表，还有数百种细菌的基因组序列正在研究中。研究所有这些细菌是不可能的，但我们可以对选定的细菌进行深入研究，因为我们开发的范例广泛适用于所有细菌。我们研究模型生物大肠杆菌中两种对压力的关键反应的调节和功能，这使得前沿研究成为可能。这些反应高度保守，并且都与相关生物体的发病机制有关。此外，我们正在定义的策略之一被证明是协调抗生素、毒力和对环境清理至关重要的制剂生产的反应范例。最后，我们的研究可能会发现抗生素的新靶点。