A novel regulatory system promotes group A Streptococcus survival in human blood

一种新的调节系统促进 A 族链球菌在人体血液中的存活

• 批准号: 10522861
• 负责人: Paul Sumby
• 金额: $ 18.05万
• 依托单位: UNIVERSITY OF NEVADA RENO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10522861
• 关键词: Animals; Area; Bacteria; Basic Science; Binding; Binding Sites; Blood; Cell surface; Cessation of life; Clinical; Data; Disease; Enterococcus; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Heterodimerization; Human; Immune; Infection; Integration Host Factors; Knowledge; Modeling; Molecular; Mus; Necrotizing fasciitis; Neutrophil Activation; Organism; Phagocytes; Phagocytosis; Pharyngitis; Phenotype; Phosphorylation; Phosphotransferases; Production; Proliferating; Property; Proteins; Proteomics; Regulation; Regulator Genes; Regulon; Research; Resistance; Respiratory Burst; Series; Side; Signaling Molecule; Small RNA; Streptococcus; Streptococcus equi; Streptococcus pyogenes; Streptococcus zooepidemicus; System; Testing; Virulence; Virulence Factors; bactericide; emerging human pathogen; enhancing factor; genome-wide analysis; human morbidity; human pathogen; innovation; insight; mortality; mutant; neutrophil; novel; novel therapeutics; pathogen; promoter; protein function; response; sensor; yeast two hybrid system

PROJECT SUMMARY The group A Streptococcus (GAS; S. pyogenes) causes significant human morbidity (>700 million infections annually) and mortality (>550,000 deaths annually), with a spectrum of infections that range from mild and self- limiting (e.g. pharyngitis) to severely invasive (e.g. necrotizing fasciitis). We have identified that FasX, the sRNA component of a novel four-component regulatory system (FasBCAX), post-transcriptionally regulates the production of key GAS virulence factors. The regulation afforded by the FasBCAX system influences GAS virulence, enhancing GAS resistance to the bactericidal properties of human blood (see preliminary data) and lethality in a mouse invasive infection model. However, there remains significant gaps in our knowledge regarding the functioning of this model regulatory system, including how FasX reduces GAS killing in human blood by ~30-fold, and how the FasBCA proteins function to enhance fasX expression ~100-fold. We will fill the regulatory, mechanistic, and virulence gaps in our knowledge by pursuing the following aims: Aim 1: Determine the mechanism by which FasX enhances GAS resistance to human blood. In this aim, we will verify our preliminary data that supports the FasX-regulon being twice the size of that currently appreciated, identify which FasX-regulated virulence factor/s are responsible for the resistance phenotype and whether their regulation by FasX modifies the binding of host molecules to the GAS cell surface, and, given our preliminary data that the resistance phenotype occurs via the inhibition of phagocytic cells, test whether neutrophil activation, phagocytosis, and/or oxidative burst is inhibited. Aim 2: Determine the mechanism by which the FasBCA proteins enhance FasX sRNA abundance. The Fas locus consists of the co-transcribed fasBCA and the separately transcribed fasX. FasB and FasC are homologous to sensor kinases while FasA is homologous to response regulators. Preliminary data are consistent with FasB and FasC forming heterodimers, rather than homodimers as classically occurs for sensor kinases. In this aim, we will unravel how the FasBCA proteins interact to enhance the transcription of fasX and other regulatory targets, and will initiate delineation of host factors capable of modulating Fas system activity. Completion of this research will greatly expand what is known about sRNA function in GAS, an organism, along with fellow Lactobacillales pathogens, in which sRNA mechanistic data is limited. We will generate basic science insights by delineating a never-before-described regulatory system in which two sensor kinases heterodimerize to activate activity. We will also generate clinical insights by delineating the molecular basis behind the ability of FasX to inhibit GAS killing in blood, a phenotype that is critical to the ability of this prevalent human pathogen to cause severe invasive disease.

项目摘要 A组链球菌（GAS; S.化脓性链球菌）导致显著的人类发病率（> 7亿感染 每年）和死亡率（每年> 550，000例死亡），感染范围从轻度到自我感染， 局限性（如咽炎）至严重侵袭性（如坏死性筋膜炎）。我们已经确定，FasX， 一种新的四组分调节系统（FasBCAX）的sRNA组分，转录后调节细胞的增殖， 关键GAS毒力因子的产生。FasBCAX系统提供的调节影响GAS 毒力，增强GAS对人体血液杀菌特性的抗性（见初步数据）， 小鼠侵袭性感染模型中的致死率。然而，我们的知识仍然存在重大差距， 关于这个模型调节系统的功能，包括FasX如何减少人类GAS杀伤 血液中的fasX表达增加了约30倍，以及FasBCA蛋白如何发挥作用以增强fasX表达约100倍。我们 将通过追求以下目标来填补我们知识中的监管、机制和毒力空白： 目的1：确定FasX增强GAS对人血液抵抗的机制。在这一目标下， 我们将验证我们的初步数据，支持FasX调节子的大小是目前的两倍， 鉴定哪些FasX调节的毒力因子负责耐药表型， FasX对它们的调节是否改变了宿主分子与GAS细胞表面的结合，并且，考虑到我们的 初步数据表明，抗性表型通过抑制吞噬细胞发生，测试是否 中性粒细胞活化、吞噬作用和/或氧化爆发被抑制。 目的2：确定FasBCA蛋白增强FasX sRNA丰度的机制。的 Fas基因座由共转录的fasBCA和单独转录的fasX组成。FasB和FasC是 与传感激酶同源，而FasA与应答调节因子同源。初步数据 与FasB和FasC形成异二聚体一致，而不是如传感器典型地发生的同源二聚体 激酶。在这个目标中，我们将揭示FasBCA蛋白如何相互作用以增强fasX的转录， 其他调控目标，并将启动划定宿主因子能够调节Fas系统的活动。 这项研究的完成将极大地扩展对生物体GAS中sRNA功能的了解， 沿着乳杆菌目病原体，其中sRNA机制数据有限。我们将生成基本的 通过描绘一个从未描述过的调节系统， 异二聚化以激活活性。我们还将通过描绘分子基础来产生临床见解 在FasX抑制血液中GAS杀伤的能力背后，这是一种对这种能力至关重要的表型。 流行的人类病原体导致严重的侵入性疾病。