Rrp2, an atypical bacterial enhancer binding protein in Borrelia burgdorferi

 描述（由申请人提供）：莱姆病病原体伯氏疏螺旋体通过涉及节肢动物（蜱）载体和小型哺乳动物的复杂生命周期在自然界中维持自身。在蜱和哺乳动物之间的循环中，B。burgdorferi改变其外表面蛋白质谱以与这两个显著不同的小生境相互作用并适应这两个不同的小生境。用于 为了全面了解莱姆病的传播和发病机制，识别疏螺旋体宿主适应的分子机制是非常重要的。在这方面，我们最近发现，一个假定的细菌增强子结合蛋白（bEBP），Rrp 2，是必不可少的B。在哺乳动物宿主中建立感染。更重要的是，我们的初步数据表明，Rrp 2，不同于其他经典的bEBPs，是必不可少的疏螺旋体生长在体外。这些数据强烈暗示Rrp 2是一种非典型的bEBP。该提案旨在阐明Rrp 2令人惊讶的重要性及其非常规活性的分子基础。在具体目标1中，我们将评估潜在关键氨基酸对Rrp 2重要性的贡献，以初步了解Rrp 2新活性的结构基础。在Specifc Aim 2中，我们将通过使用全局转录组分析来识别受Rrp 2影响的新的σ54/Rpos独立因子。这些结合的结构和功能研究将不仅推进我们对疏螺旋体毒力表达的调控控制的理解，而且还解释了我们对细菌σ54生物学的机制理解的重大范式转变。

 DESCRIPTION (provided by applicant): Borrelia burgdorferi, the etiological agent of Lyme disease, maintains itself in nature via a complex life cycle involving an arthropod (tick) vector and small mammals. During its cycle between ticks and mammals, B. burgdorferi alters its outer surface protein profiles to interact with and adapt to these two dramatically diverse niches. For a complete understanding of Lyme disease transmission and pathogenesis, it is of major importance to discern the molecular mechanisms of borrelial host adaptation. In this regard, we recently discovered that a putative bacterial enhancer binding protein (bEBP), Rrp2, is essential for B. burgdorferi to establish infection in mammalian hosts. More importantly, our preliminary data indicate that Rrp2, distinct from other classical bEBPs, is essential for borrelial growth in vitro. These data strongly implicate Rrp2 as an atypical bEBP. This proposal seeks to elucidate the molecular bases underlying Rrp2's surprising essentiality and its unconventional activity. In Specific Aim 1, we will assess the contributions of potential key amino acids to Rrp2's essentiality to gain initial insights into the structural basis of Rrp2's novel activity. In Specifc Aim 2, we shall identify new σ54/RpoS-independent factors influenced by Rrp2 by using global transcriptome analyses. These combined structural and functional studies will not only advance our understanding of regulatory control over borrelial virulence expression, but also account for a major paradigm-shift in our mechanistic understanding of bacterial σ54 biology.