DNA recombinational repair in Helicobacter pylori

描述(申请人提供)：幽门螺杆菌感染大约50%的人的胃，并导致一系列人类胃病。它高度适应于在人类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利基，会导致细菌DNA损伤。幽门螺杆菌表现出已知的最高水平的遗传多样性，而这种多样性的一个主要贡献者是DNA重组的高频率。我们推测，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中，包括识别受损的DNA和随后招募重组修复蛋白。这项建议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。这4个基因的基因靶点突变菌株将被检测它们对DNA损伤剂的敏感性，它们在氧化和酸性应激条件下的生存情况，以及它们的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使用小鼠感染模型进行研究。第二个探索性目标是通过从随机转座子突变文库中筛选丝裂霉素C敏感菌株来鉴定幽门螺杆菌重组修复系统的其他成分。或者，将通过交联法和免疫共沉淀法鉴定与RecN、RecB或RecR相互作用的蛋白质。我们的研究旨在揭示幽门螺杆菌在胃环境中生存的独特能力所涉及的基因，并为DNA重组修复的独特机制提供新的见解。与公共卫生相关：幽门螺杆菌持续感染人类胃粘膜，并导致消化性溃疡疾病和胃癌等严重疾病。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.