DNA recombinational repair in Helicobacter pylori

描述（申请人提供）：幽门螺杆菌感染大约50%的人类的胃，并导致一系列人类胃部疾病。它高度适应于在人胃粘膜中保持持久性，胃粘膜是一个充满氧化和酸应激剂的小生境，可引起细菌DNA损伤。H.幽门螺杆菌在细菌中表现出最高水平的遗传多样性，这种多样性的主要贡献者是高频率的DNA重组。我们假设，DNA损伤的修复重组既有利于H。幽门螺杆菌的遗传多样性，并有助于其在体内的生存。H.幽门螺杆菌可能具有DNA重组修复的独特机制，特别是对于初始步骤，包括识别受损DNA和随后募集重组修复蛋白。本提案的探索性目标是确定参与DNA重组修复的四种推定蛋白（RecN，RecJ，RecR和HP 1553）的作用。将检查这4个基因中的基因靶向突变株对DNA损伤剂的敏感性、在氧化和酸性应激条件下的存活率以及DNA重组频率。这些基因/蛋白在H.将使用感染的小鼠模型来研究幽门螺杆菌。第二个探索性目标是鉴定H. pylori通过从随机转座子诱变文库中筛选丝裂霉素C敏感菌株。或者，与RecN、RecB或RecR相互作用的蛋白质将通过交联和免疫共沉淀方法鉴定。我们的研究旨在阐明H。pylori基因参与了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了新的见解。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，如消化性溃疡和胃癌。对DNA重组修复系统的研究将有助于我们理解H.幽门螺杆菌可以适应并持续存在于人的胃中。

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.