Genetic Mechanisms in Borrelia burgdorferi Pathogenesis

描述（由申请人提供）：莱姆病的病原体伯氏疏螺旋体是美国最常见的节肢动物传染病。尽管从基因组序列中获得了信息，但关于这种细菌如何对其在自然界中占据的不同生态位（节肢动物和哺乳动物）做出反应的了解甚少，并且没有分子上定义的调控系统。 研究人员的长期目标是了解B。burgdorferi调节基因表达以响应环境信号，并将这种知识与导致发病的特定分子的合成联系起来。本申请的目的是表征氧特异性调节网络，并将其作用与B生命周期中重要基因的表达相关。burgdorferi。 假设溶解氧是B. burgdorferi利用它来感知其环境并通过调节位点perR动员反应。 PerR是一种金属调节蛋白，其调节参与氧化应激反应的基因的表达。B。burgdorferi perR突变体对过氧化氢具有抗性，表明PerR抑制B中氧化还原应答基因的表达。burgdorferi。 研究人员还确定，perR突变体在与应激反应无关的其他基因中被去抑制，这表明PerR构成了一个调节子。研究人员提出了以下具体目标来表征PerR调节子：（1）鉴定组成PerR调节子的基因。研究者将使用基于基因组和蛋白质组学的方法来确定响应于氧化还原状态的由PerR调节的基因;（2）确定PerR调节的机制。PerR结合金属并且可以是氧化还原响应性的。研究人员建议确定哪些辅因子调节PerR活性;（3）将受细胞氧化还原状态调节的蛋白质与体内表达和保护性免疫相关。 几种抗原在perR突变体中和当氧水平低时上调。PerR调节的抗原在氧化应激期间表达，并且当氧气受限时被抑制，将作为保护性免疫原进行测试。 研究人员预测，PerR调节子对莱姆病的生理学和发病机制都很重要，因为它分别调节抵抗有毒氧物质所需的基因表达和粘附所需的因子。

DESCRIPTION (provided by applicant): Borrelia burgdorferi, the etiologic agent of Lyme disease, is the most frequent arthropod borne infection in the United States. Despite the information obtained from the genome sequence, very little is understood regarding how this bacterium responds to the distinct niches it occupies in nature (arthropods and mammals) and no regulatory systems have been molecularly defined. The investigators long-term goal is to understand how B. burgdorferi modulates gene expression in response to environmental signals and to link this knowledge to the synthesis of specific molecules that contribute to pathogenesis. The objectives of this application are to characterize an oxygen-specific regulatory network and relate its role to the expression of genes important in the life cycle of B. burgdorferi. The hypothesis is that dissolved oxygen is an important cue that B. burgdorferi uses to sense its environment and mobilize a response via the regulatory locus perR. PerR is a metallo-regulatory protein that modulates the expression of genes involved in the oxidative stress response. B. burgdorferi perR mutants are resistant to hydrogen peroxide, suggesting that PerR represses expression of redox responsive genes in B. burgdorferi. The investigators also determined that the perR mutant is de-repressed in additional genes unrelated to the stress response, suggesting that PerR constitutes a regulon. The investigators propose to characterize the PerR regulon with the following Specific Aims: (1) Identify the genes that comprise the PerR regulon. The investigators will use a genomic and proteomic based approach to determine genes regulated by PerR in response to the redox status; (2) Determine the mechanism of PerR regulation. PerR binds metals and may be redox responsive. The investigators propose to determine which co-factors modulate PerR activity; and (3) Relate proteins regulated by the redox status of cells to in vivo expression, and protective immunity. Several antigens are upregulated in perR mutants and when oxygen levels are low. PerR regulated antigens expressed during periods of oxidative stress and repressed when oxygen is limiting will be tested as protective immunogens. The investigators predict that the PerR regulon is important for both the physiology and pathogenesis of Lyme borreliosis as it modulates the expression of genes required for resistance to toxic oxygen species and factors required for adhesion, respectively.