Molecular Regulation of Biological Stress Response

描述（由申请人提供）：所有细胞都具有监视和反应系统，使它们能够通过感知细胞损伤并刺激基因表达中的反作用反应来适应环境应激。这些系统旨在检测热休克或其他环境损伤引起的细胞组成变化，并做出相应反应以确保生存。在革兰氏阴性细菌中，细菌应激反应（ESR）系统检测源自内膜和外膜之间的周质空间的分子信号，然后激活细胞质中应激特异性基因的表达。在许多这些生物体中，ESR途径的激活是毒力或致病性所必需的。例如，铜绿假单胞菌，囊性纤维化患者呼吸道感染的主要原因，通过激活ESR途径转化为最具毒性的形式。因此，了解激活该通路的分子事件和机制可以为设计新的治疗策略提供有价值的见解。E.大肠杆菌RseB和铜绿假单胞菌MucB是邻位调节蛋白，在它们各自的生物体中作为细菌应激反应中的第一承诺步骤的抑制剂起作用。对抗RseB和MucB活性的细胞应激信号肯定存在，但在我开始这个项目时还没有被发现。在初步研究中，我发现这种信号似乎是外膜成分的衍生物，由细胞应激事件期间的片段化或不完全合成产生。我提出并将测试一个模型，在该模型中，这些分子在应激过程中形成结合RseB，抑制其正常的抑制活性，从而激活应激反应。建立这个模型的有效性将代表理解特定的压力信号是如何产生和感知以促进细胞存活的重要一步。具体目标（1）我将确定负责结合E的特定分子的化学决定簇。coliRseB中表达，并抑制其活性。(2)我将确定这些分子结合并调节RseB活性的分子机制。(3)我将测试在前面的目标中阐明的机制是否在细胞中起作用。 公共卫生相关性：许多细菌的致病性取决于它们检测和应对细胞应激的能力。因此，了解这些检测和反应系统如何在分子水平上运作是一个重要的目标，对人类健康的影响。本申请中描述的研究将解决新发现的分子应激信号被细菌检测到并用于启动基因和蛋白质表达变化的机制，这使得这些生物体能够在恶劣的环境中生存。

DESCRIPTION (provided by applicant): All cells have surveillance and response systems that allow them to adapt to environmental stress by sensing cellular damage, and stimulating a counteractive response in gene expression. These systems are designed to detect changes in cellular composition caused by heat shock or other environmental insults and to react accordingly to ensure survival. In Gram-negative bacteria, the envelope-stress response (ESR) system detects molecular signals originating in the periplasmic space between the inner and outer membranes and then activates expression of stress-specific genes in the cytoplasm. In many of these organisms, activation of the ESR pathway is required for virulence or pathogenicity. For example, Pseudomonas aeruginosa, the major cause of respiratory infections in patients with cystic fibrosis, converts into its most virulent form by activating the ESR pathway. Thus, understanding the molecular events and mechanisms that activate this pathway could provide valuable insights for the design of novel therapeutic strategies. E. coli RseB and P. aeruginosa MucB are orthologous regulatory proteins that function as inhibitors of the first committed step in the envelope-stress response in their respective organisms. Cellular stress signals that antagonize RseB and MucB activity must exist but had not been identified when I began this project. In preliminary studies, I have discovered that this signal appears to be a derivative of an outer membrane component, generated either by fragmentation during cellular stress events or incomplete synthesis. I propose and will test a model in which these molecules formed during stress bind to RseB, suppress its normal inhibitory activity, and therefore activate the envelope-stress response. Establishing the validity of this model would represent an important step forward in understanding how specific stress signals are generated and sensed to facilitate cellular survival. Specific Aims (1) I will identify the chemical determinants of specific molecules that are responsible for binding E. coli RseB and inhibiting its activity. (2) I will determine the molecular mechanism(s) by which these molecules bind to and modulate RseB activity. (3) I will test if the mechanisms elucidated in the preceding aims operate in the cell. PUBLIC HEALTH RELEVANCE: The pathogenicity of many bacteria depends on their ability to detect and respond to cellular stress. Thus, understanding how these detection and response systems operate at the molecular level is an important goal with implications for human health. The research described in this application will address the mechanisms by which a newly discovered molecular stress signal is detected by bacteria and used to initiate changes in gene and protein expression, which allow these organisms to survive in inhospitable environments.