RpoS Regulation of Borrelia burgdorferi Genes in vivo

莱姆病（LD）的病原体伯氏疏螺旋体（Borrelia burgdorferi，Bb）在自然界中维持在复杂的地方病环境中。 一个涉及哺乳动物储库宿主和蜱媒的循环。为了维持这种循环，BB必须调整其 转录组，蛋白质组和代谢组的节肢动物和哺乳动物宿主来源的信号，因为它穿梭 两人之间Rrp 2/RpoN/RpoS通路作为一个核心参与者已经得到了广泛的认可， 疏螺旋体基因调控我们的实验室长期以来一直站在努力表征 在蜱虫和哺乳动物中由RpoS控制的基因。不幸的是，我们仍然不知道 RpoS-RNA聚合酶（RNAP）是自然界中的全酶。本提案通过以下方式解决这一不足： 结合最先进的转录组学和诱变方法来确定个体在何处/何时 基因有助于RpoS的双宿主“任务”。在以前的出版物中，我们在描绘 体内RpoS-ON和-OFF状态的时间边界。然而，近年来，我们对这一问题的思考 二分法变得更加微妙。我们现在相信RpoS调节子的轮廓改变了 在RpoS-ON状态期间，以主机特定的方式深刻地影响这些结果，与对 Hk 1/Rrp 1通路，产生了我们的中心假设-RpoS调节子的动态性质反映了 非RpoS调节途径与控制RpoS的ON/OFF状态的机制的汇合， RpoS-RNAP的输出。沿着这些思路，我们现在提出滴答相位信号分子c-di-GMP是 这对监管的交叉对话至关重要。此外，我们和其他人已经发现，c-di-GMP结合蛋白PlzA 促进RpoS的表达，从而促进小鼠中Bb毒力的表达，这是地方性流行病周期的一个阶段， Hk 1/Rrp 1通路关闭。我们努力阐明PlzA作为c-di-GMP信号传导介导剂的这种双功能作用 在蜱虫中的C-di-GMP-独立调节剂和小鼠中的RpoS将我们的领域带入未知领域。最后， 在过去的几年中，我们分析了在透析膜室中培养的哺乳动物宿主适应性螺旋体， 揭示RpoS不仅上调蜱传播和哺乳动物感染所需的基因， 抑制蜱虫定植和适应所需的基因。我们最近的研究表明，RpoS-RNAP 通过封闭其σ70启动子直接抑制滴答期基因的转录。我们将测试此“RpoS”， repressor模型，并探索c-di-GMP拮抗哺乳动物RpoS介导的阻遏的新数据 适应宿主的Bb.我们的长期目标是全面了解 Rrp 2/RpoN/RpoS通路完成了其基本使命--引导LD螺旋体从蜱虫到小鼠并返回 再我们将通过定义蜱和小鼠中RpoS调节子的轮廓来实现这一点（目标1）;阐明 c-di-GMP-和PlzA-依赖性信号传导与RpoS通路的会聚（Aim 2）;以及 哺乳动物宿主适应性Bb中RpoS介导的滴答时相基因抑制及c-di-GMP的拮抗作用 (Aim 3）。

Borrelia burgdorferi (Bb), the agent of Lyme disease (LD), is maintained in nature within a complex enzootic cycle involving a mammalian reservoir host and a tick vector. To sustain this cycle, Bb must adjust its transcriptome, proteome, and metabolome to arthropod- and mammalian host-derived signals as it shuttles between the two. The Rrp2/RpoN/RpoS pathway has gained widespread recognition as a central player in borrelial gene regulation. Our laboratory has long been at the forefront of efforts to characterize the cohort of genes controlled by RpoS in both the tick and mammal. Unfortunately, we still do not know the entire output of RpoS-RNA polymerase (RNAP) holoenzyme in nature. The present proposal addresses this shortfall by combining state-of-the-art transcriptomic and mutagenesis methodologies to determine where/when individual genes contribute to RpoS's dual-host `mission'. In prior publications, we were instrumental in delineating the temporal boundaries of the RpoS-ON and –OFF states in vivo. In recent years, however, our thinking about this dichotomy has become much more nuanced. We now believe that the contours of the RpoS regulon change profoundly and in host-specific fashion during the RpoS-ON state These results, in concert with studies of the Hk1/Rrp1 pathway, give rise to our central hypothesis--the dynamic nature of the RpoS regulon reflects the confluence of non-RpoS regulatory pathways with mechanisms that govern the ON/OFF states of RpoS and the output of RpoS-RNAP. Along these lines, we now propose that the tick-phase signaling molecule c-di-GMP is crucial to this regulatory cross-talk. Moreover, we and others have found that the c-di-GMP-binding protein PlzA promotes expression of RpoS and, hence, Bb virulence in the mouse, the stage of the enzootic cycle in which the Hk1/Rrp1 pathway is OFF. Our efforts to clarify this bifunctional role of PlzA as a mediator of c-di-GMP signaling in ticks and a c-di-GMP-independent regulator of RpoS in mice takes our field into uncharted territory. Lastly, in years past, our analysis of mammalian host-adapted spirochetes cultivated in dialysis membrane chambers revealed that RpoS not only upregulates genes required for tick transmission and mammalian infection but also represses genes required for colonization and adaptation to the tick. Our recent work suggests that RpoS-RNAP directly represses transcription of tick-phase genes by occluding their σ70 promoters. We will test this `RpoS as repressor' model and explore new data that c-di-GMP antagonizes RpoS-mediated repression in mammalian host-adapted Bb. Our long-term objective is to achieve an integrative understanding of how the Rrp2/RpoN/RpoS pathway fulfills its essential mission--guiding LD spirochetes from tick to mouse and back again. We will accomplish this by defining the contours of the RpoS regulon in ticks and mice (Aim 1); clarifying the convergence of c-di-GMP- and PlzA-dependent signaling with the RpoS pathway (Aim 2); and dissecting RpoS-mediated repression of tick-phase genes and its antagonism by c-di-GMP in mammalian host-adapted Bb (Aim 3).