Virulence regulation by BadR in the Lyme disease spirochete

摘要 伯氏疏螺旋体 (Bb) 是莱姆病的病原体，通过复杂的生命周期在自然界中维持自身 涉及节肢动物（蜱）媒介和小型哺乳动物。在蜱虫和哺乳动物之间的循环中，Bb 为了与这两个不同的利基互动并适应，经历了巨大的适应性变化。 此前，我们发现 ROK 阻遏蛋白的同源物 BadR 与 rpoS 启动子区域结合， 抑制 rpoS 的表达。此外，我们的初步研究结果表明，BadR 有很多 除了抑制 rpoS 表达之外，与 Bb 的生命周期具有更广泛的生物学相关性。首先，需要BadR Bb 的最佳生长。其次，BadR 在哺乳动物感染的建立中起着至关重要的作用。相反 与野生型菌株相比，badR 缺失突变体无法感染小鼠，这表明 BadR 控制着 与 Bb 在宿主中存活相关的关键效应蛋白的表达。 badR的表型缺陷 小鼠感染中的突变体与有据可查的 RpoN-RpoS 调节途径无关，因为所有 badR 突变体中仍然产生 BosR、Rrp2、RpoN 和 RpoS。事实上，我们初步的全球 使用 RNA-seq 进行的转录组分析已鉴定出许多 BosR/RpoS 独立基因 坏R。此外，我们发现 badR 在 Bb 的蜱哺乳动物感染周期中表达。这些 综合数据得出我们的假设，即 BadR 是控制 Bb 宿主适应的主调节器，并且 毒力表达。这一假设将在两个具体目标中得到解决。在本提案的目标 1 中，我们将 采用全局转录组/蛋白质组分析来定义各种体外和体内的整个 BadR 调节子 体内条件。在目标 2 中，我们将根据我们的全局转录组/蛋白质组选择 BadR 调控的基因 分析并描述了它们对 Bb 感染周期的贡献。这些综合研究将（i）完善我们的 有关 BadR 介导的基因调控的知识； (ii) 提供对体内的变革性理解 调节子的重要性； (iii) 确定新的毒力决定因素。由此产生的结果可能导致 制定预防和/或治疗莱姆病的新策略。

ABSTRACT Borrelia burgdorferi (Bb), 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, Bb undergoes dramatic adaptive changes in order to interact with and adapt to these two disparate niches. Previously, we found that BadR, a homologue of ROK repressors, binds to the rpoS promoter region and represses the expression of rpoS. Moreover, our preliminary findings have suggested that BadR has much broader biological relevance to the life cycle of Bb other than repressing rpoS expression. First, BadR is required for Bb's optimal growth. Second, BadR plays a vital role in the establishment of mammalian infection. Contrary to the wild-type strain, a badR deletion mutant is incapable of infecting mice, suggesting that BadR governs expression of key effector proteins associated with Bb's survival in the host. Phenotypic defects of the badR mutant in mice infection are NOT related to the well documented RpoN-RpoS regulatory pathway, because all of BosR, Rrp2, RpoN, and RpoS are still produced in the badR mutant. In fact, our preliminary global transcriptomic analyses using RNA-seq have identified numerous BosR/RpoS-independent genes regulated by BadR. In addition, we found that badR is expressed throughout Bb's tick-mammal infectious cycle. These combined data give rise to our hypothesis that BadR is a master regulator governing Bb's host adaption and virulence expression. This hypothesis will be addressed in two Specific Aims. In Aim 1 of this proposal, we will employ global transcriptome/proteome profiling to define the entire BadR regulon under various in vitro and in vivo conditions. In Aim 2, we will select BadR-regulated genes based on our global transcriptome/proteome analyses and characterize their contributions to Bb's infectious cycle. These combined studies will (i) refine our knowledge on BadR-mediated gene regulation; (ii) provide a transformative understanding of the in vivo importance of the regulon; and (iii) identify novel virulence determinants. Resultant findings could lead to the development of new strategies to prevent and/or treat Lyme disease.