Virulence regulation by BadR in the Lyme disease spirochete

摘要 莱姆病的病原体伯氏疏螺旋体（Borreliaburgdorferi，Bb）在自然界中通过复杂的生活史维持自身的生命 涉及节肢动物（蜱）媒介和小型哺乳动物。在蜱和哺乳动物之间的循环中，Bb 经历了戏剧性的适应性变化，以便与这两个截然不同的小生境相互作用并适应它们。 以前，我们发现BadR是ROK阻遏物的同源物，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，Bb的生命周期具有更广泛的生物学相关性。首先，需要BadR 为了BB的最佳成长其次，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缺失突变体不能感染小鼠，这表明BadR控制 与Bb在宿主中的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已被充分证明的RpoN-RpoS调节途径无关，因为所有 在badR突变体中仍然产生BosR、Rrp 2、RpoN和RpoS。事实上，我们初步的全球 使用RNA-seq的转录组学分析已经鉴定了许多由转录因子调节的BosR/Rpos非依赖性基因。 BadR.此外，我们发现badR在Bb的蜱-哺乳动物感染周期中表达。这些 综合数据使我们的假设，BadR是一个主调节Bb的主机适应， 毒力表达这一假设将在两个具体目标中得到解决。在本建议的目标1中，我们将 使用整体转录组/蛋白质组分析来定义各种体外和体内条件下的整个BadR调节子。 体内条件。在目标2中，我们将基于我们的全局转录组/蛋白质组选择BadR调控的基因 分析和描述它们对Bb感染周期的贡献。这些综合研究将（i）完善我们的 BadR介导的基因调控知识;（ii）提供对体内 调节子的重要性;和（iii）确定新的毒力决定因素。由此产生的结果可能导致 开发预防和/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.