Analysis of pH dependent regulation in B. burgdorferi

描述(申请人提供)：莱姆病是一种由伯氏疏螺旋体引起的多系统疾病，通过硬蜱的叮咬传播给哺乳动物。仅在美国，2000年就报告了超过17,000例病例，使其成为头号可报告的节肢动物传播的传染病。在没有喂食、受感染的扁虱体内，细菌寄生在扁虱的中肠，中肠的pH/温度为8.0-8.4/23摄氏度。在取食和传播期间，由于宿主的血液流入，螺旋体的pH/温度从8.0-8.4/23摄氏度转变为6.0-7.4/35摄氏度。B.burgdorferi通过改变不同基因的表达来适应新的环境，以响应环境提示，如pH和温度的变化。我们建议描绘参与对pH反应的基因调节的分子机制。利用亲和层析、质谱学和DNase I足迹技术，我们提出了鉴定、鉴定和灭活伯氏假单胞菌伴生基因家族54的正调控因子。该基因家族包含13个基因，它们位于线形质粒上。这些基因在感染或适应过程中的作用尚不清楚，但基因家族成员bba64、bba65、bba66和bba73受pH变化的调节，并已在模型系统中与急性莱姆关节炎有关。通过了解这种细菌如何能够感知环境并改变基因表达以响应环境线索的变化，我们希望了解i)适应和感染所需的调节成分，以及ii)靶基因的pH调节在哺乳动物发病中的作用。

DESCRIPTION (provided by applicant): Lyme disease is a multi-systemic disorder caused by Borrelia burgdorferi that spreads to mammals by the bite of an Ixodes tick. In the U.S. alone over 17,000 cases were reported in 2000, making it the number one reportable arthropod-borne infectious disease. In unfed, infected ticks the bacteria reside in the tick midgut, which has a pH/temperature of 8.0-8.4/23degreesC. During tick feeding and transmission the spirochetes experience a shift in pH/temperature from 8.0-8.4/23degreesC to 6.0- 7.4/35degreesC due to the influx of blood from the host. B. burgdorferi adapts to its new surroundings by altering the expression of different genes in response to environmental cues, such as changes in pH and temperature. We propose to delineate the molecular mechanisms that are involved in gene regulation in response to pH. Using affinity chromatography, mass spectroscopy and DNase I footprinting we propose to identify, characterize and inactivate the positive regulator of paralogous gene family 54 in B. burgdorferi. This gene family contains 13 genes that are located on linear plasmids. The role of these genes in the infection or adaptation process is unknown, but gene family members bba64, bba65, bba66, and bba73 are regulated by changes in pH and have been implicated in contributing to acute Lyme arthritis in model systems. By understanding how this bacterium is able to sense the environment and alter gene expression in response to changes in environmental cues, we hope to gain insight into i) the regulatory components necessary for adaptation and infection and ii) the role of pH regulation of target genes in mammalian pathogenesis.