B FRAGILIS OXYGEN STRESS RESPONSE AND INFECTION

描述(改编自申请者摘要)：厌氧 有机体，脆弱类杆菌对有毒物质具有特殊的抵抗力 氧和其他氧化应激的影响。这种抵抗力可以 归因于氧化应激反应(OSR)的诱导 将对其反应进行研究，以证明其在糖尿病发病机制中的作用。 脆弱类杆菌感染。预计新的机制将 自由基保护和新的抗氧化防御策略将 被揭开。这一观点得到了以下事实的支持：脆弱杆菌 很早就从其他真细菌中分化出来，并独立进化 长时间暴露在氧气中存活的能力。此外，由于这一点 是一种厌氧菌，它可能对氧气有严格的要求 保护导致了独一无二的高度 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 脆弱芽孢杆菌对氧化应激的耐受性以及确定这些 对致命性有贡献。这项提案的目标是：1)确定 并在蛋白质和基因水平上对OSR进行表征。最初， 人们的注意力将集中在OSR的一个子集上，即对过氧化氢和 过氧物(HPR)。一组hpr基因将被克隆和分析，以及 这些数据将被用来建立一个表达的HPR蛋白的目录 在氧化应激过程中。2)HPR的调控 将首先使用使用过氧化氢酶的模型系统进行研究 吉恩，卡特B。这将集中在转录调控和 氧化应激调节分子的鉴定。系统将 当hpr基因可用时，将其扩展到包括它们。3) 确定hpr控制基因的特定突变对 在氧化应激下存活。这些基因中的一个或多个的突变将 通过等位基因交换构建，并测试它们的能力 在各种形式的氧化应激下存活下来。变种人将受到 各种生化测试以确定其发病机制。 保护，例如DNA修复或大分子保护。4)监管者 负责控制HPR的调节子将被克隆并发挥其作用 在总体上，OSR将被确定。

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.