Impact of regulatory cross-talk on the pathophysiology of emergent acapsular group A streptococcus

监管串扰对新出现的无荚膜 A 族链球菌病理生理学的影响

• 批准号: 10301505
• 负责人: SAMUEL A SHELBURNE
• 金额: $ 24.3万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-12 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10301505
• 关键词: Address; Adherence; Affect; Animal Model; Bacterial Infections; Binding; Biological Assay; Blood; Cell Surface Proteins; Cell surface; Cytotoxin; Data; Encapsulated; Epithelial Cells; Exposure to; Extracellular Matrix; Functional disorder; Genes; Genetic Transcription; Genome; Genomic approach; Goals; Human; Hyaluronic Acid; Incidence; Infection; Large-Scale Sequencing; Link; Luciferases; Mediating; Molecular; Mus; Pathogenesis; Phagocytes; Phagocytosis; Population; Production; Promoter Regions; Proteins; Regulation; Regulator Genes; Regulatory Pathway; Reporter; Research; Resistance; Role; Signal Transduction; Streptococcal Infections; Streptococcus pyogenes; Streptolysins; System; Testing; Transcript; United States; Variant; Virulence; Virulence Factors; antimicrobial peptide LL-37; base; capsule; comparative genomics; human pathogen; improved; in vivo; innovation; insight; mouse model; multiple myeloma M Protein; neutrophil; novel; pathogen; population based; promoter; response

PROJECT SUMMARY The hyaluronic acid capsule of the major human pathogen group A Streptococcus (GAS) has classically been considered essential to infectivity. GAS is divided into emm types based on variation in the emm gene that encodes for the cell-surface, anti-phagocytic M protein. It has recently been appreciated that GAS strains from emm types lacking capsule are increasingly causing serious human infections to the point where some 30% of invasive GAS isolates are acapsular. How acapsular GAS causes infection is not currently known although it has been postulated that acapsular GAS strains elaborate high levels of a key cytotoxin, streptolysin O (Slo). Contrary to this conjecture, we have found that multiple acapsular emm types do not produce high levels of Slo, and thus the long term goal of our research is to elucidate the mechanistic basis of acapsular GAS pathophysiology. Through a comparative genomics approach, we have identified that acapsular GAS emm types have distinct compositions of the promoters of mga and emm which encode the key transcriptional regulator multi-gene activator (Mga) and M protein, respectively. Moreover, we have discovered that the control of virulence (CovRS) two-component gene regulatory system specifically impacts mga and emm transcript levels in acapsular relative to encapsulated GAS. These, and other, findings set the stage for this proposal which seeks to test the hypothesis that mga and emm promoter composition are critical to the infectivity of acapsular GAS by allowing for regulation by CovRS, which is critical for GAS to sense and respond to host signals. In specific aim 1, we will determine how variation in mga and emm promoters of acapsular GAS compared to encapsulated GAS alters the composition of the cell surface of acapsular emm4 and emm89 strains in response to the human antimicrobial peptide LL-37. We will also assess the impact of mga and emm promoter composition on acapsular GAS adherence to human epithelial cells and human extracellular matrix components, survival in human blood, resistance to phagocytosis, and virulence in a mouse model. In specific aim 2, we will determine if the changes observed in the mga and emm promoters of acapsular GAS allow for direct regulation by CovR and is the mechanism by which CovS inactivation influences mga and emm transcript levels. We will investigate in vivo interaction of CovR with mga and emm promoters and attempt to identify promoter regions that are key to CovR-based regulation using a luciferase based reporter system. We also will assess whether CovR directly represses emm in acapsular GAS independent of Mga. Completion of the research outlined herein will significantly augment understanding of the molecular mechanisms underlying the emergence of acapsular GAS which are a major cause of GAS infection yet remain poorly understood relative to encapsulated strains.

项目概要 人类主要病原体 A 组链球菌 (GAS) 的透明质酸胶囊历来被认为是 被认为对传染性至关重要。 GAS 根据 emm 基因的变异分为 emm 类型， 编码细胞表面抗吞噬 M 蛋白。最近人们认识到，GAS 菌株来自 缺乏荚膜的 emm 类型越来越多地导致严重的人类感染，以至于大约 30% 侵入性气体分离株是无荚膜的。目前尚不清楚无囊 GAS 如何引起感染，但 据推测，无荚膜 GAS 菌株可产生高水平的关键细胞毒素链球菌溶血素 O (Slo)。 与这个猜想相反，我们发现多种无囊 emm 类型不会产生高水平的 Slo， 因此，我们研究的长期目标是阐明胶囊 GAS 的机制基础 病理生理学。通过比较基因组学方法，我们发现无荚膜 GAS emm 类型具有不同的 mga 和 emm 启动子组成，编码关键转录 分别是调节剂多基因激活剂（Mga）和M蛋白。此外，我们还发现，控制 毒力 (CovRS) 双组分基因调控系统特别影响 mga 和 emm 转录水平 相对于封装的气体而言，处于封装状态。这些以及其他发现为该提案奠定了基础 试图检验 mga 和 emm 启动子组成对于荚膜感染性至关重要的假设 GAS 允许 CovRS 进行调节，这对于 GAS 感知和响应宿主信号至关重要。在 具体目标 1，我们将确定胶囊 GAS 的 mga 和 emm 启动子与 封装的 GAS 改变了无荚膜 emm4 和 emm89 菌株的细胞表面组成作为响应 人类抗菌肽LL-37。我们还将评估 mga 和 emm 启动子成分的影响 囊膜 GAS 与人上皮细胞和人细胞外基质成分的粘附，存活率 人类血液、对吞噬作用的抵抗力以及小鼠模型中的毒力。在具体目标 2 中，我们将确定 如果在胶囊 GAS 的 mga 和 emm 启动子中观察到的变化允许 CovR 直接调节 这是 CovS 失活影响 mga 和 emm 转录水平的机制。我们将调查 CovR 与 mga 和 emm 启动子的体内相互作用，并尝试识别关键的启动子区域 使用基于荧光素酶的报告系统进行基于 CovR 的调节。我们还将评估 CovR 是否直接 抑制胶囊 GAS 中的 emm，与 Mga 无关。完成本文概述的研究将 显着增强对无囊 GAS 出现的分子机制的理解 这是 GAS 感染的主要原因，但相对于封装菌株而言，人们仍然知之甚少。