Transcriptional Control of the Helicobacter pylori RpoN Regulon

描述(申请人提供)：幽门螺杆菌是人类消化性溃疡疾病和多种其他疾病的病原体，包括胃癌和粘膜相关淋巴瘤。幽门螺杆菌需要运动才能穿过胃粘膜层并定植于胃上皮细胞，而幽门螺杆菌利用一簇极鞭毛来完成这一任务。细菌中鞭毛基因表达的调控是复杂的，涉及到将鞭毛基因的表达与鞭毛的组装结合在一起的转录层次。拟议研究的长期目标是确定幽门螺杆菌调节鞭毛基因表达的机制。另一种Sigma因子RpoN是几个H.Pylori鞭毛基因转录所必需的。这些依赖于RpoN的基因的转录也需要flgs/flgR双组分系统。幽门螺杆菌依赖于RpoN的鞭毛基因的表达与鞭毛蛋白输出装置有关，因为编码输出装置组件的基因突变干扰了RpoN调节子的表达。输出装置影响RpoN调节子表达的机制尚不清楚。本项目的目标是确定输出装置控制H.Pylori RpoN鞭毛调节子表达的分子机制。工作假说是，输出装置通过分泌RpoN调节子的抑制剂或通过蛋白质-蛋白质相互作用影响传感器激酶flgs的活性，从而影响Hp RpoN调节子的转录。这一假设将在三个具体目标上得到客观检验。第一个特定的目标将确定一种成分活性形式的FlgR是否绕过输出装置突变，以允许RpoN依赖的报告基因的表达。在第二个具体目标中，带有突变的幽门螺杆菌菌株将被锁定在有利于杆状/钩型底物的构象中，以确定它们如何影响依赖RpoN的报告基因的表达。第三个特定目的是通过破坏编码HP1042的基因并确定这种突变如何影响Hp中依赖RpoN的报告基因的表达，来确定新的蛋白质HP1042是否是RpoN调节子的抑制因子。这项拟议的工作与美国国立卫生研究院促进公共健康的使命相关，因为研究结果可能会导致确定控制或检测幽门螺杆菌的新目标。这些信息对于开始减少与幽门螺杆菌感染相关的发病率和死亡率至关重要。公共卫生相关性：幽门螺杆菌是消化性溃疡疾病和其他胃病的病原体，在美国每年估计导致100万人住院和6500人死亡。拟议的研究结果可能导致确定控制或检测幽门螺杆菌的新靶点，这对开始降低与这种重要病原体相关的发病率和死亡率非常重要。

DESCRIPTION (provided by applicant): Helicobacter pylori is the causative agent of peptic ulcer disease and a variety of other diseases in humans, including gastric cancer and mucosal-associated lymphoma. Motility is required for H. pylori to cross the gastric mucous layer and colonize the gastric epithelium, and H. pylori use a cluster of polar flagella to accomplish this. Regulation of flagellar gene expression in bacteria is complex and involves a transcriptional hierarchy that couples the expression of flagellar genes with assembly of the flagellum. The long-term objective of proposed research is to identify mechanisms used by H. pylori to regulate flagellar gene expression. The alternative sigma factor RpoN is needed for transcription of several H. pylori flagellar genes. Transcription of these RpoN-dependent genes also requires the FlgS/FlgR two-component system. Expression of H. pylori RpoN-dependent flagellar genes is linked to the flagellar protein export apparatus as mutations in genes encoding components of the export apparatus interfere with expression the RpoN regulon. The mechanism by which the export apparatus influences expression of the RpoN regulon is unknown. The goal of this project is to identify the molecular mechanism by which the export apparatus controls expression of the H. pylori RpoN flagellar regulon. The working hypothesis is that the export apparatus affects transcription of the H. pylori RpoN regulon by secreting an inhibitor of the RpoN regulon or influencing the activity of the sensor kinase FlgS through protein-protein interactions. This hypothesis will be tested objectively in three specific aims. The first specific aim will determine if a constitutively active form of FlgR bypasses export apparatus mutations to allow expression of RpoN-dependent reporter genes. In the second specific aim H. pylori strains with mutations that lock the export apparatus in a conformation that favors rod-/hook-type substrates will be examined to see how they influence expression of RpoN-dependent reporter genes. The third specific aim will determine if the novel protein HP1042 is an inhibitor of the RpoN regulon by disrupting the gene encoding this protein and determining how this mutation affects expression of RpoN-dependent reporter genes in H. pylori. The proposed work is relevant to NIH's mission of promoting public health in the United States as the results of the studies may lead to identification of new targets for the control or detection of H. pylori. This information is essential to begin to reduce the morbidity and mortality associated with H. pylori infections. PUBLIC HEALTH RELEVANCE: Helicobacter pylori is a causative agent of peptic ulcer disease and other gastric diseases, causing an estimated 1 million hospitalizations and 6,500 deaths each year in the United States. Results of the proposed studies may lead to the identification of new targets for the control or detection of H. pylori, which is important to begin to reduce the morbidity and mortality associated with this significant pathogen.