Molecular Regulation of Biological Stress Response

描述（由申请人提供）：所有细胞都有监视和反应系统，通过感知细胞损伤和刺激基因表达中的反作用反应来适应环境压力。这些系统旨在检测由热休克或其他环境损害引起的细胞成分变化，并作出相应反应以确保生存。在革兰氏阴性细菌中，包膜-应激反应（ESR）系统检测来自内外膜之间的质周间隙的分子信号，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，激活ESR通路是毒性或致病性所必需的。例如，铜绿假单胞菌（Pseudomonas aeruginosa）是囊性纤维化患者呼吸道感染的主要原因，它通过激活ESR途径转化为最致命的形式。因此，了解激活这一途径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。大肠杆菌RseB和铜绿假单胞菌MucB是同源调节蛋白，在它们各自的生物体中作为包膜-应激反应第一步的抑制剂。拮抗RseB和MucB活性的细胞应激信号一定存在，但在我开始这个项目时还没有被发现。在初步研究中，我发现该信号似乎是外膜成分的衍生物，由细胞应激事件期间的断裂或不完全合成产生。我提出并将测试一个模型，在这个模型中，这些分子在应激过程中与RseB结合，抑制其正常的抑制活性，从而激活包膜-应激反应。建立该模型的有效性将代表着理解特定应激信号是如何产生和感知以促进细胞存活的重要一步。我将确定负责结合大肠杆菌RseB并抑制其活性的特定分子的化学决定因素。(2)我将确定这些分子结合和调节RseB活性的分子机制。(3)我将测试上述目标阐明的机制是否在细胞中起作用。

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.