Global regulatory interactions in bacterial pathogenesis

描述(由申请人提供)：流感嗜血杆菌能够有效和长期地定植在人的鼻咽粘膜上，并能够引起侵袭性疾病，包括中耳炎、肺炎，更罕见的是脑膜炎。在前基因组时代，已经确定了许多与流感嗜血杆菌毒力有关的因素。利用基因组序列和新技术的出现，如全球表达谱，我们打算促进对这种生物的关键毒力特征的理解。脂多糖(LPS)结构修饰是流感嗜血杆菌毒力的重要决定因素。使用DNA微阵列的表达谱，辅之以经典的方法，我们最近发现了在流感嗜血杆菌中氧化还原调节和脂多糖修饰之间以前不为人知的联系。此外，我们在流感嗜血杆菌中分离到一个水手转座子插入突变，该突变破坏了对其中一个修饰的氧化还原控制(在脂多糖中添加了一个称为CHOP的磷酰胆碱表位)，并导致了流感嗜血杆菌感染动物模型中明显的定植缺陷。这些观察结果对环境信号在体内调节内毒素结构具有潜在的意义。我们建议使用我们实验室产生的这些信号和调节突变体来研究氧化还原信号在控制流感嗜血杆菌毒力基因中的作用。我们为研究流感嗜血杆菌而开发的全球基因组方法将有助于我们分析内毒素修饰是如何随着环境条件的变化而调节的。我们还将确定在发病机制中发挥作用的其他基因是否在影响内毒素修饰的不同氧化还原条件下被共调控、反向调控或结构性转录。我们相信，这些研究将对宿主环境的生理适应与细菌细胞表面结构的协调产生之间的关系提供重要的见解，这些结构对于与宿主细胞的相互作用或逃避免疫反应至关重要。具体地说，我们将：1.表征参与调控CHOP细胞表面内毒素修饰的氧化还原控制机制。2.研究流感嗜血杆菌信号通路在上皮细胞相互作用和呼吸道感染模型中的作用。3.研究氧化还原信号系统对毒力因子的协调调节。

DESCRIPTION (provided by applicant): Haemophilus influenzae efficiently and chronically colonizes the human nasopharyngeal mucosa, and is capable of causing invasive disease including otitis media, pneumonia, and, more rarely, meningitis. A number of factors involved in H. influenzae virulence have been identified in the pre-genomic era. Taking advantage of the genome sequence and the advent of new technologies, such as global expression profiling, we intend to advance understanding of critical virulence characteristics of this organism. Lipopolysaccharide (LPS) structural modifications are essential virulence determinants for H. influenzae. Using expression profiling with DNA microarrays, complemented by classical approaches, we have recently uncovered a previously unappreciated link between redox regulation and LPS modifications in H. influenzae. In addition, we have isolated a mariner transposon insertion mutation in H. influenzae that disrupts redox control over one such modification (addition of a phosphorylcholine epitope, termed ChoP, to the LPS) and also results in a pronounced colonization defect in an animal model of H. influenzae infection. These observations are of potential significance for in vivo modulation of the LPS structure by environmental signals. We propose to use such signaling and regulatory mutants generated in our laboratory to examine the role of redox signaling in controlling virulence genes in H. influenzae. Global genomic approaches we have developed for studies of H. influenzae will facilitate our analysis of how LPS modifications are modulated in response to environmental conditions. We will also determine whether other genes that play a role in pathogenesis are coregulated, inversely regulated, or constitutively transcribed under the varied redox conditions that affect LPS modification. We believe that these studies will provide important insights into the relationship between physiological adaptations to the host environment and the coordinated production of bacterial cell-surface structures critical for interactions with host cells or for evading the immune response. Specifically, we will: 1. Characterize the redox control mechanisms involved in the regulation of the ChoP cell surface LPS modification. 2. Investigate the role of signaling pathways in H. influenzae in the context of epithelial cell interactions and in a model of respiratory tract infection. 3. Examine coordinate regulation of virulence factors by redox signaling systems.