Functional analysis of a Group A streptococcal locus important for fitness in soft tissue

项目总结 病原体对不同环境的适应能力是其生存、感染、 以及寄主体内的坚持性。作为一种严格的人类病原体，化脓性链球菌(A组) 链球菌，GAS)每年导致50多万人死亡。即使它通常表现为 表面感染(例如链球菌性咽喉炎)，气体也会导致危及生命的疾病(例如坏死性疾病)。 筋膜炎，中毒性休克综合征)，当它从最初的感染部位侵入正常的无菌组织时。它 必须更好地了解气体的病理生理学和遗传要求 需要感染不同的宿主环境。我们实验室进行了体内转座子测序(TN-SEQ) 在临床相关的M1T1 5448气体菌株中进行筛选以确定气体所需的遗传要求 在上皮下层组织中，我们发现了一个以前未描述的基因座(ScfCDE) 对这种环境来说是必不可少的。仅基于同源性，scfCDE被预测为编码一个假定的 ABC进口商。由于该基因座以前从未进行过实验检验，因此这项提议将探索 ScfCDE在GAS细胞途径和毒力中的作用，假设scfCDE编码 膜相关蛋白，在宿主组织的气体适合性中发挥不可或缺的作用，导入底物 进入对气体病理生理学很重要的细胞内。本研究将对scfCDE基因座进行检测 在养分利用和应激诱导环境中识别潜在底物的表型 这些蛋白质可以运输、探索其遗传结构、表达和操纵子的调节， 最后，探讨scfCDE是否对人类血液中的定植、生长和先天的生长有重要作用。 免疫逃逸采用已建立的体内和体外GAS感染模型。因为scfCDE是 节省天然气和其他燃料，成功完成这一项目将潜在地做出贡献 开发针对GAS和其他重要革兰氏+病原体的新治疗策略。

PROJECT SUMMARY A pathogen’s ability to adapt to different environments is an important factor in its survival, infection, and persistence within its host. As a strict human pathogen, Streptococcus pyogenes (Group A Streptococcus, GAS) causes over 500,000 deaths annually. Even though it commonly manifests as superficial infections (e.g. strep throat), GAS also causes life-threatening diseases (e.g. necrotizing fasciitis, toxic shock syndrome) when it invades normally sterile tissues from initial sites of infection. It is imperative to gain a better understanding of GAS pathophysiology and the genetic requirements it needs to infect varying host environments. Our lab performed an in vivo transposon sequencing (Tn-seq) screen in a clinically relevant M1T1 5448 GAS strain to define the genetic requirements needed for GAS fitness in the subepithelial tissue, where we found a previously uncharacterized locus (scfCDE) to be essential for this environment. Based on homology alone, scfCDE are predicted to encode for a putative ABC importer. Because the locus has not been experimentally examined before, this proposal will explore the functional roles of scfCDE in GAS cellular pathways and virulence, hypothesizing that scfCDE encode membrane-associated proteins that play integral roles in GAS fitness in host tissue, importing a substrate into the cell important for GAS pathophysiology. This study will examine the scfCDE locus for phenotypes in nutrient utilization and in stress-induced environments to identify potential substrates these proteins may transport, explore its genetic architecture, expression, and regulation of the operon, and lastly, explore whether scfCDE are important for colonization, growth in human blood, and innate immune evasion using established in vivo and ex vivo models of GAS infection. Since scfCDE are conserved in GAS and other Firmicutes, successful completion of this project will potentially contribute to the development of novel therapeutic strategies against GAS and other important Gram+ pathogens.