Outer surface protein gene expression in B. burgdorferi

描述（由申请人提供）：莱姆病是美国最常见的节肢动物传播疾病，由伯氏疏螺旋体感染引起。伯氏疏螺旋体合成几种外表面蛋白（Osps），包括OspA、OspB和OspC。OspA是莱姆病疫苗的靶标，被认为与伯氏疏螺旋体与蜱虫载体肠道的结合有关。OspC被认为是一种传播或哺乳动物定植因子，其合成是在蜱虫喂养过程中诱导的。OspA和OspB与OspC的变异可能是伯氏疏螺旋体适应蜱媒介和哺乳动物宿主的不同环境，为环境转变做准备的一种手段。我们的假设是DNA超卷绕感知环境信号并将其转导到改变的基因表达程序中，其中ospC转录直接受到DNA超卷绕的影响。本项目拟利用分子遗传学和生物化学技术，剖析外表面蛋白基因表达的调控。Gac和Hbb是两种结构DNA结合蛋白，可以改变伯氏疏螺旋体的DNA结构和超卷曲。我们将通过突变伯氏疏螺旋体的Gac和Hbb基因来检测Gac和Hbb在ospC转录中的作用。此外，我们将通过构建ospC启动子突变体来定义顺式作用序列。我们相信我们将能够探索伯氏疏螺旋体外表面蛋白基因表达变化的机制，这将有助于了解该病原体的基本生物学，并有助于改进诊断、预防和治疗策略。

DESCRIPTION (provided by applicant): Lyme disease, the most common arthropod-borne disease in the United States, is caused by infection with the spirochete Borrelia burgdorferi. B. burgdorferi synthesizes several outer surface proteins (Osps), including OspA, OspB and OspC. OspA is the target in the Lyme disease vaccine and is thought to be involved in the binding of B. burgdorferi to the gut of its tick vector. OspC is thought to be a transmission or mammalian colonization factor and its synthesis is induced during tick feeding. The variation of OspA and OspB versus OspC is likely a means by which B. burgdorferi adapts to the different environments of the tick vector and mammalian host, and prepares for the environmental transition. Our hypothesis is that DNA supercoiling senses environmental signals and transduces them into an altered gene expression program in which ospC transcription is directly affected by DNA supercoiling. This project proposes to dissect, using molecular genetic and biochemical techniques, the regulation of outer surface protein gene expression. Gac and Hbb are two architectural DNA-binding proteins that alter DNA structure and supercoiling in B. burgdorferi. We will genetically assay the role of Gac and Hbb in ospC transcription by mutating the gac and hbb genes in B.burgdorferi. In addition, we will define cis-acting sequences by constructing ospC promoter mutants. We believe that we will be able to probe the mechanism of the variation in outer surface protein gene expression in B. burgdorferi, which will contribute to the understanding of the basic biology of this pathogen and can lead to improved diagnostic, prevention and treatment strategies.