B FRAGILIS OXYGEN STRESS RESPONSE AND INFECTION

B fragilis 氧应激反应和感染

• 批准号: 6328746
• 负责人: CHARLES J. SMITH
• 金额: $ 18.39万
• 依托单位: EAST CAROLINA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-01 至 2002-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6328746
• 关键词: Bacteroides; DNA footprinting; bacterial disease; bacterial genetics; gene deletion mutation; gene expression; gene mutation; genetic regulation; genetic regulatory element; glutamate ammonia ligase; molecular cloning; nucleic acid sequence; oxidative stress; virulence

DESCRIPTION (Adapted from the Applicant's Abstract): The anaerobic organism, Bacteroides fragilis is exceptionally resistant to the toxic effects of oxygen and other oxidative stress. This resistance can be attributed to induction of an oxidative stress response (OSR) and this response will be studied to document its role in the pathogenesis of Bacteroides fragilis infection. It is expected that new mechanisms of free radical protection and novel antioxidant defense strategies will be uncovered. This idea is supported by the fact that B. fragilis diverged very early from other eubacteria and has independently evolved the ability to survive extended exposure to oxygen. Further, since this is an anaerobe, it is likely to have stringent requirements for oxygen protection that have resulted in the development of unique highly protective antioxidants. The long term goals of this research are to understand the basic physiological and genetic processes responsible for tolerance of B. fragilis to oxidative stress and to determine how these contribute to virulence. The objectives for this proposal are: 1) Define and characterize the OSR at the protein and genetic levels. Initially, attention will focus on a subset of the OSR, resistance to H2O2 and peroxides (HPR). A set of HPR genes will be cloned and analyzed, and these data will be used to establish a catalog of HPR proteins expressed during the course of oxidative stress. 2) Regulation of the HPR regulon will be studied initially using a model system employing the catalase gene, katB. This will focus on transcriptional regulation and the identification of oxidative stress regulatory molecules. The system will be expanded to include the HPR genes as they become available. 3) Determine the effect of specific mutations in HPR-controlled genes on survival to oxidative stress. Mutants in one or more of these genes will be constructed by allelic exchange and tested for their ability to survive various forms of oxidative stress. Mutants will be subjected to a variety of biochemical tests to determine their mechanism of protection e.g. DNA repair or macromolecule protection. 4) The regulator responsible for control of the HPR regulon will be cloned and its role in the overall OSR will be determined.

描述（改编自申请人的摘要）：厌氧 生物体，菌脂叶片对有毒的耐药性异常抗性 氧和其他氧化应激的影响。这种阻力可以是 归因于诱导氧化应激反应（OSR），这 将研究反应以记录其在 细菌性脆弱的感染。预计新机制 自由基保护和新颖的抗氧化防御策略将 被发现。这个想法得到了B. fragilis的事实的支持 很早就与其他eubacteria分歧，并且已经独立发展 延长暴露于氧气的能力。此外，此外 是厌氧菌，可能对氧气有严格的要求 保护产生独特的保护 保护性抗氧化剂。这项研究的长期目标是 了解负责的基本生理和遗传过程 脆弱链球菌对氧化应激的耐受性，并确定如何 有助于毒力。该提案的目标是：1）定义 并在蛋白质和遗传水平上表征OSR。最初， 注意将集中于OSR的子集，对H2O2的抵抗力和 过氧化物（HPR）。一组HPR基因将被克隆和分析，并且 这些数据将用于建立表达的HPR蛋白的目录 在氧化应激过程中。 2）HPR调节的调节 最初将使用使用过氧化氢酶的模型系统研究 Gene，Katb。这将着重于转录调节和 氧化应激调节分子的鉴定。系统将 扩展到包括HPR基因可用时。 3） 确定特异性突变对HPR控制基因对 生存到氧化应激。其中一个或多个基因中的突变体将 由等位基因交换构建，并测试其能力 生存各种形式的氧化应激。突变体将受到 各种生化测试以确定其机制 保护，例如DNA修复或大分子保护。 4）调节器 负责控制HPR规范的控制及其作用 在整个OSR中，将确定。