Genetic Mechanisms in Borrelia burgdorferi Pathogenesis

描述（由申请人提供）：伯氏疏螺旋体是莱姆病的病原，是美国最常见的节肢动物感染。尽管从基因组序列中获得了信息，但对于这种细菌如何对其在自然界（节肢动物和哺乳动物）中占据的独特生态位做出反应，人们知之甚少，也没有分子定义的调节系统。研究人员的长期目标是了解伯氏疏螺旋体如何根据环境信号调节基因表达，并将这些知识与导致发病的特定分子的合成联系起来。本应用程序的目的是表征氧特异性调控网络，并将其与伯氏疏螺旋体生命周期中重要基因的表达联系起来。假设溶解氧是伯氏疏螺旋体通过调节位点perR感知环境和调动反应的重要线索。PerR是一种金属调节蛋白，可调节参与氧化应激反应的基因表达。伯氏疏螺旋体perR突变体对过氧化氢具有抗性，表明perR抑制伯氏疏螺旋体氧化还原反应基因的表达。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构成了一个规则。研究人员提出以以下具体目标来表征PerR调控子：(1)鉴定组成PerR调控子的基因。研究人员将使用基于基因组学和蛋白质组学的方法来确定受PerR调控的基因对氧化还原状态的响应；(2)确定PerR调控机制。PerR与金属结合，可能具有氧化还原反应。研究人员建议确定哪些辅助因素调节PerR活性；(3)将细胞氧化还原状态调节的蛋白与体内表达和保护性免疫联系起来。在perR突变体中，当氧水平较低时，几种抗原上调。PerR调节抗原在氧化应激期间表达，在氧气限制时被抑制，将作为保护性免疫原进行测试。研究人员预测，PerR调控在莱姆病的生理和发病机制中都很重要，因为它分别调节对有毒氧的抗性所需基因的表达和粘附所需因子的表达。

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.