DNA recombinational repair in Helicobacter pylori

描述（由申请人提供）：幽门螺杆菌感染约50%的人类胃，并导致一系列人类胃疾病。它非常适合在人胃粘膜中维持持久性，胃粘膜是一个充满氧化和酸应激剂的生态位，导致细菌DNA损伤。幽门螺杆菌在细菌中表现出最高水平的遗传多样性，而这种多样性的主要原因是DNA重组的高频率。我们假设通过重组修复DNA损伤既促进了幽门螺杆菌的遗传多样性，又有助于其在体内的生存。幽门螺杆菌可能有一种独特的DNA重组修复机制，特别是在最初的步骤，包括识别受损的DNA和随后的重组修复蛋白的募集。本研究的探索性目标是确定四种可能的蛋白质（RecN, RecJ， RecR和HP1553）在DNA重组修复中的作用。将检测这4个基因的基因靶向突变株对DNA损伤剂的敏感性、在氧化和酸胁迫条件下的存活率以及DNA重组频率。这些基因/蛋白在幽门螺杆菌体内存活中的作用将通过小鼠感染模型进行研究。第二个探索目标是通过从随机转座子突变文库中筛选丝裂霉素c敏感菌株，确定幽门螺杆菌重组修复系统的其他组成部分。或者，与RecN、RecB或RecR相互作用的蛋白将通过交联和共免疫沉淀方法进行鉴定。我们的研究旨在揭示幽门螺杆菌基因参与细菌在胃环境中生存的独特能力，并为DNA重组修复的独特机制提供新的见解。公共卫生相关性：幽门螺杆菌持续感染人类胃粘膜，并导致严重的疾病，如消化性溃疡疾病和胃癌。研究DNA重组修复系统将有助于我们了解幽门螺杆菌如何适应并在人体胃中持续存在。

DESCRIPTION (provided by applicant): Helicobacter pylori infects the stomachs of approximately 50% of humans and results in a series of human gastric diseases. It is highly adapted to maintain persistence in the human gastric mucosa, a niche full of oxidative and acid stress agents that cause bacterial DNA damage. H. pylori exhibits the highest level of genetic diversity known among bacteria, and a major contributor to this diversity is the high frequency of DNA recombination. We hypothesize that the repair of DNA damage by recombination both facilitates H. pylori's genetic diversity and contributes to its in vivo survival. H. pylori likely has a unique mechanism for DNA recombinational repair, particularly for the initial steps including the recognition of damaged DNA and subsequent recruitment of recombination repair proteins. The exploratory goals of this proposal are to define the roles of four putative proteins (RecN, RecJ, RecR, and HP1553) involved in DNA recombinational repair. Gene-targeted mutant strains in these 4 genes will be examined for their sensitivity to DNA damaging agents, for their survival under oxidative and acid stress conditions, and for their DNA recombination frequency. The roles of these genes/proteins in the in vivo survival of H. pylori will be studied using a mouse model of infection. A secondary exploratory goal is to identify additional components of the recombinational repair system in H. pylori by screening for mitomycin C-sensitive strains from a random transposon mutagenesis library. Alternatively, the proteins that interact with RecN, RecB, or RecR will be identified via cross-linking and coimmunoprecipitation approaches. Our studies are designed to shed light on H. pylori genes involved in the bacterium's unique ability to survive the gastric environment, and to provide novel insight into the unique mechanisms of DNA recombinational repair. PUBLIC HEALTH RELEVANCE: Helicobacter pylori persistently infects the human gastric mucosa and causes serious conditions such as peptic ulcer disease and gastric cancers. Studying the DNA recombinational repair system will help us understand how H. pylori can adapt to and persist in the human stomach.