The RpoN-RpoS regulatory pathway in Borrelia burgdorferi

描述（由申请人提供）：伯氏疏螺旋体（Bb），莱姆病螺旋体，当它在不同的蜱虫和哺乳动物宿主之间循环时，经历了巨大的适应性变化。然而，关于调节Bb的传染性和毒力的遗传调控网络知之甚少。最近，我们在Bb中发现了一个新的调控途径，其中一个备选sigma因子（sigma N, sigmaN, sigma54, RpoN）调节另一个备选sigma因子（sigma S, sigmaS, sigma38, RpoS）的表达，后者反过来控制与螺旋体毒力相关的关键膜脂蛋白的表达。本研究建议在这一初步观察的基础上，从遗传和分子水平上研究新的rpo - rpos调控途径，因为它与Bb的传染性和毒力有关。在具体目标1中，我们将确定rpo - rpos调控通路的激活因子；研究将集中于检测Bb的“反应调节蛋白2”（Rrp2）的作用，该蛋白被预测为转录增强子结合蛋白。在具体目标2中，我们将研究RpoN控制RpoS表达的机制，重点是(i)定位RpoS启动子和（ii）评估RpoN及其激活子（Rrp2）与RpoS启动子和上游区域的结合。Specific Aim 3的研究将探讨rpo - rpos通路调节一种原型差异调节脂蛋白OspC表达的机制。重点将放在分析ospC启动子的关键特征，这些特征使RpoN通过RpoS控制ospC启动子。在Specific Aim 4中，我们将研究rpo - rpos通路对Bb感染动物、定殖蜱、媒介传播和致病能力的影响。最后，在Specific Aim 5中，我们将使用DNA微阵列来更全面地识别受rpo - rpos调控途径影响的Bb基因。这些联合研究将有助于进一步表征Bb中新的rpo - rpos调控途径，并有可能识别与Bb复杂寄生策略的许多方面有关的感染和/或毒力相关基因。

DESCRIPTION (provided by applicant): Borrelia burgdorferi (Bb), the Lyme disease spirochete, undergoes dramatic adaptive changes as it cycles in nature between its diverse tick and mammalian hosts. However, little is known regarding the genetic regulatory networks that modulate Bb's infectivity and virulence. Recently, we discovered a novel regulatory pathway in Bb, wherein one alternative sigma factor (sigma N, sigmaN, sigma54, RpoN) regulates the expression of another alternative sigma factor (sigma S, sigmaS, sigma38, RpoS) which, in turn, governs the expression of key membrane lipoproteins associated with borrelial virulence. This study proposes to build on this initial observation and investigate, at the genetic and molecular levels, the novel RpoN-RpoS regulatory pathway as it pertains to Bb's infectivity and virulence. In Specific Aim 1, we will identify the activator of the RpoN-RpoS regulatory pathway; studies will focus on examining a role for the "response regulator protein 2" (Rrp2) of Bb that is predicted to be a transcriptional enhancer-binding protein. In Specific Aim 2, we will examine the mechanism by which RpoN controls the expression of RpoS, with emphasis on (i) mapping the rpoS promoter and (ii) assessing the binding of RpoN and its activator (Rrp2) to the rpoS promoter and upstream regions. Studies in Specific Aim 3 will investigate the mechanism by which the RpoN-RpoS pathway regulates the expression of a prototypic differentially regulated lipoprotein, OspC. Emphasis will be placed on analyzing key features of the ospC promoter that engender its control by RpoN via RpoS. In Specific Aim 4, we will examine the influence of the RpoN-RpoS pathway on Bb's ability to infect animals, colonize ticks, be vector-transmitted, and cause disease. Finally, in Specific Aim 5, we will use DNA microarrays to identify more globally those genes of Bb influenced by the RpoN-RpoS regulatory pathway. These combined studies will be instrumental in further characterizing the novel RpoN-RpoS regulatory pathway in Bb and for potentially identifying infection- and/or virulence-associated genes that contribute to many aspects of Bb's complex parasitic strategy.