The RpoN-RpoS regulatory pathway in Borrelia burgdorferi

伯氏疏螺旋体中的 RpoN-RpoS 调控途径

• 批准号: 8021018
• 负责人: MICHAEL V. NORGARD
• 金额: $ 39.23万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8021018
• 关键词: Address; Animals; Area; Arthropods; Bacteria; Bacteria sigma factor KatF protein; Binding Proteins; Borrelia; Borrelia burgdorferi; Complement; Complex; Data; Disease; Elements; Foundations; Funding; Gene Expression Regulation; Genes; Genetic; Genetic Transcription; Intervention; Investigation; Lac Repressors; Lead; Life Cycle Stages; Lipoproteins; Lyme Disease; Mammals; Membrane; Methods; Modeling; Names; Nature; OmpR protein; Operon; OspC protein; Pathogenesis; Pathway interactions; Pattern; Phase; Phenotype; Principal Investigator; Process; Progress Reports; Regulation; Regulatory Pathway; Research; Research Personnel; Role; Sigma Factor; System; Ticks; Virulence; Work; decorin; decorin binding protein B; enhancer binding protein; enzootic; mutant; novel; promoter; public health relevance; therapeutic vaccine; trait; transmission process; vector

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. Prior to work conducted by the principle investigator over the past funding interval, little was known regarding the genetic regulatory networks that modulate Bb's adaptive changes contributing to Bb's infectivity and virulence. To this end, we discovered a novel regulatory pathway in Bb, wherein one alternative sigma factor (CN, RpoN) regulates the expression of another alternative sigma factor (Cs, RpoS) that, in turn, governs the expression of key membrane lipoproteins associated with Bb's virulence. The pathway is controlled by an enhancer-binding protein, response regulator protein-2 (Rrp2), which first must be activated for the subsequent activation of RpoN and the consequent transcription of rpoS. Although the discovery of this regulatory network in Bb has represented an important advance in the Lyme disease field, it also has prompted many new questions regarding its direct and indirect regulatory effects, how the pathway intersects with other regulatory mechanisms, and how and to what extents various genes of Bb are influenced. Selected areas of investigation over the next funding interval will continue to address some of these salient information gaps. Accordingly, the Specific Aims of this proposal are: (1) To discern those genes directly influenced by the RpoN-RpoS pathway. We shall combine our expertise in Bb microarrays with our newly developed lac repressor/operator system to artificially control the expression of rpoS in Bb. Identified genes will become the subject of further studies (Aim 4); (2) To investigate the mechanism by which the RpoN-RpoS pathway regulates atypical expression of the decorin-binding protein (DbpB/A) operon. The dbpBA operon is under the control of the RpoN-RpoS pathway, but it has an expression pattern different from other genes controlled by RpoS (e.g., ospC). As such, dbpBA may be a model of how certain genes influenced by the pathway also are subjected to another layer of regulation. Emphasis will be placed on analyzing key features of the dbpBA promoter and upstream cis-elements; (3) To examine the expression of rpoS over the complete enzootic life cycle (tick and mammalian phases) of Bb; and (4) To examine the phenotypes of Bb mutants deficient in selected RpoS-dependent genes. These efforts will provide an expanding foundation for further characterizing the novel RpoN-RpoS regulatory network in Bb, and for potentially identifying regulatory and virulence-associated genes that contribute to many aspects of Bb's complex parasitic strategy. Understanding the roles of these genes could lead to new intervention strategies (vaccines, therapeutics) for Lyme disease. PUBLIC HEALTH RELEVANCE: This project seeks to understand better how the Lyme disease bacterium uses a novel method of gene regulation (alternative sigma factor cascade regulatory network) to strategically govern the expression of a number of its virulence traits critical to its transmission between arthropod (tick) and mammalian hosts. Emphasis will be placed on identifying those genes directly controlled by this regulatory network, and in determining their roles in tick transmission, infectivity for mammals, and induction of disease. Understanding the roles of these genes in transmission and pathogenesis processes could lead to new intervention strategies (vaccines, therapeutics) for Lyme disease.

描述（由申请人提供）：伯氏疏螺旋体（Bb）是莱姆病螺旋体，在自然界中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。在主要研究者在过去的资助期间进行工作之前，人们对调节 Bb 适应性变化、导致 Bb 传染性和毒力的基因调控网络知之甚少。为此，我们在 Bb 中发现了一条新的调控途径，其中一个替代 sigma 因子（CN、RpoN）调节另一种替代 sigma 因子（Cs、RpoS）的表达，而后者又控制与 Bb 毒力相关的关键膜脂蛋白的表达。该通路由增强子结合蛋白、反应调节蛋白 2 (Rrp2) 控制，首先必须激活该蛋白以随后激活 RpoN 以及随后的 rpoS 转录。尽管 Bb 中这一调控网络的发现代表了莱姆病领域的重要进展，但它也引发了许多新问题，包括其直接和间接调控作用、该途径如何与其他调控机制相交叉，以及 Bb 的各种基因如何以及在多大程度上受到影响。下一个资助期间选定的调查领域将继续解决其中一些显着的信息差距。因此，该提案的具体目标是：（1）识别那些直接受RpoN-RpoS途径影响的基因。我们将把我们在 Bb 微阵列方面的专业知识与我们新开发的 lac 阻遏物/操纵子系统相结合，以人为地控制 Bb 中 rpoS 的表达。已识别的基因将成为进一步研究的主题（目标4）； (2)探讨RpoN-RpoS通路调控核心蛋白聚糖结合蛋白(DbpB/A)操纵子非典型表达的机制。 dbpBA操纵子受RpoN-RpoS途径控制，但其表达模式与RpoS控制的其他基因（例如ospC）不同。因此，dbpBA 可能是受该途径影响的某些基因如何受到另一层调控的模型。重点将放在分析 dbpBA 启动子和上游顺式元件的关键特征； (3) 检测 Bb 整个地方性动物生命周期（蜱期和哺乳动物期）中 rpoS 的表达； (4) 检查缺乏选定的 RpoS 依赖基因的 Bb 突变体的表型。这些努力将为进一步表征 Bb 中的新型 RpoN-RpoS 调控网络提供扩展的基础，并可能识别有助于 Bb 复杂寄生策略许多方面的调控和毒力相关基因。了解这些基因的作用可能会导致莱姆病的新干预策略（疫苗、治疗方法）。 公共健康相关性：该项目旨在更好地了解莱姆病细菌如何使用一种新的基因调控方法（替代西格玛因子级联调控网络）来战略性地控制对其在节肢动物（蜱）和哺乳动物宿主之间传播至关重要的许多毒力特征的表达。重点将放在识别由该调控网络直接控制的基因，并确定它们在蜱传播、哺乳动物感染性和疾病诱导中的作用。了解这些基因在传播和发病过程中的作用可能会导致莱姆病的新干预策略（疫苗、治疗方法）。