Mechanisms of SFG Rickettsia-Host Interactions

SFG 立克次体与宿主相互作用的机制

基本信息

批准号：
10293664
负责人：
REBECCA L LAMASON
金额：
$ 55.82万
依托单位：
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-12 至 2025-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10293664
关键词：
Ankyrin Repeat Bacterial Infections Bacterial Proteins Biochemical Biological Biological Assay Biology Cell Adhesion Molecules Cell physiology Cell-Cell Adhesion Cells Cellular biology Cessation of life Complement Complex Cytosol Development Diagnostic Ectopic Expression Exanthema Future Genes Genetic Genetic Variation Genetic study Goals Human Impairment Infection Integration Host Factors Intercellular Junctions Invaded Label Laboratories Lead Life Life Cycle Stages Location Mediating Metabolic Microscopy Modeling Modernization Molecular Mutagenesis Pathogenesis Pathogenicity Pathway interactions Phase Plasmids Property Proteins Proteomics Research Rickettsia Rickettsia Infections Rickettsia parkeri Site Structure System Techniques Testing Therapeutic Intervention Tick-Borne Diseases Tick-Borne Infections Time Type IV Secretion System Pathway United States National Institutes of Health Vascular Diseases Vinculin Widespread Disease Work base combat design forward genetics genetic approach genetic manipulation improved insight interest member mutant pathogen pathogenic bacteria prevent spotted fever targeted treatment therapeutic target tick-borne tool

项目摘要

PROJECT SUMMARY/ABSTRACT A subset of emerging, but poorly characterized tickborne diseases in the U.S. are caused by Spotted Fever Group (SFG) Rickettsia. These obligate intracellular bacterial pathogens cause mild-to-life-threatening vascular diseases in humans and have a limited set of diagnostics and therapeutic interventions. To promote widespread disease, SFG Rickettsia species have evolved dynamic strategies to invade host cells, escape into the cytosol, and spread from cell to cell. We hypothesize that SFG Rickettsia coordinate their complex life cycle by delivering an arsenal of secreted bacterial proteins (i.e., effectors) that reprogram host cell processes. Unfortunately, the identity and host targets of these secreted effectors have remained largely unknown. Furthermore, direct analysis of the secretion systems and putative effectors have been hampered due to challenges in growing and genetically manipulating these pathogens in the lab. To overcome this barrier, we recently adapted forward genetics and plasmid-based complementation to the model SFG member Rickettsia parkeri, allowing for powerful functional-genetic studies of SFG Rickettsia pathogenesis. Using these tools, we discovered that the secreted effector Sca4 promotes a late stage of cell-to-cell spread by manipulating host cell-cell adhesion. Additionally, transposon mutagenesis of a secreted effector of unknown function (RARP-1) and a component of the anomalous Rickettsia Type 4 secretion system (VirB6e) impairs distinct stages of R. parkeri infection. This proposal will leverage these key advances to examine how a secretion system and secreted effectors promote different steps of the R. parkeri infectious life cycle. Here, we combine our functional-genetic strategies and expertise in host cell biology, with modern biochemical techniques to reveal critical, mechanistic insights into SFG Rickettsia pathogenesis. In Aim 1, we will examine the function and secretome of the T4SS component VirB6e. In Aim 2, we will determine how the secreted effector RARP-1 promotes R. parkeri infection. In Aim 3, we will elucidate how Sca4 specifically targets host cell-cell adhesion complexes during R. parkeri cell-to-cell spread. Collectively, the proposed research will dramatically improve our fundamental understanding of Rickettsia biology and Rickettsia-host interactions and reveal therapeutic targets to prevent or treat tickborne diseases.

项目概要/摘要美国出现的一部分新出现但特征不明的蜱传疾病是由斑点热引起的组 (SFG) 立克次体。这些专性细胞内细菌病原体会导致轻度至危及生命的血管病变人类疾病的诊断和治疗干预措施有限。为促进广泛疾病，SFG立克次体物种已经进化出动态策略来侵入宿主细胞，逃入细胞质，并从一个细胞传播到另一个细胞。我们假设 SFG 立克次体通过传递来协调其复杂的生命周期重新编程宿主细胞过程的分泌细菌蛋白（即效应器）库。不幸的是，这些分泌效应器的身份和宿主目标在很大程度上仍然未知。此外，直接分析由于生长和发育方面的挑战，分泌系统和假定的效应器的功能受到了阻碍。在实验室中对这些病原体进行基因操作。为了克服这一障碍，我们最近进行了调整对 SFG 模型成员 Parkeri 立克次体进行遗传学和基于质粒的互补，从而允许 SFG 立克次体发病机制的强大功能遗传学研究。使用这些工具，我们发现分泌型效应器 Sca4 通过操纵宿主细胞与细胞的粘附来促进细胞间传播的后期阶段。此外，功能未知的分泌效应子 (RARP-1) 的转座子诱变和异常的 4 型立克次体分泌系统 (VirB6e) 会损害帕克里立克次体感染的不同阶段。这该提案将利用这些关键进展来研究分泌系统和分泌效应器如何促进 R. Parkeri 感染生命周期的不同步骤。在这里，我们结合了我们的功能遗传策略和宿主细胞生物学方面的专业知识，利用现代生化技术来揭示关键的、机制性的见解 SFG 立克次体发病机制。在目标 1 中，我们将检查 T4SS 组件的功能和分泌组 VirB6e。在目标 2 中，我们将确定分泌的效应器 RARP-1 如何促进帕克里氏菌感染。在目标 3 中，我们将阐明 Sca4 如何在 R. parkeri 细胞与细胞之间特异性靶向宿主细胞-细胞粘附复合物传播。总的来说，所提出的研究将极大地提高我们对立克次体生物学和立克次体与宿主的相互作用，并揭示预防或治疗蜱传的治疗靶点疾病。