Mechanisms of Pheromone-Controlled Lysozyme Resistance and Surface Display of Streptococcus pyogenes

项目总结/摘要 人们对化脓性链球菌的生理或调节因子知之甚少， 使其能够在类似病毒的状态和有毒状态之间切换。该提案描述了 寻求继续定义和表征群体感应的实验方法 调节途径，对应于与无毒生活方式一致的表型， 化脓性链球菌（A组链球菌; GAS）。群体感应网络 利用短疏水肽（SHP）信息素的酿脓链球菌和信息素 受体Rgg 2和Rgg 3调节几种表型，包括生物膜发育、细胞增殖、细胞凋亡、细胞凋亡和细胞凋亡。 聚集、氨基糖苷类敏感性和溶菌酶抗性，通过未知的机制。 我们的研究表明，这些表型中的每一种都依赖于一种小蛋白的表达， 未知函数我们假设这种蛋白质，称为StcB，是一种抑制剂， 靶向细胞壁的肽聚糖键的酶。其他研究表明， StcB是一种胞壁蛋白水解酶，称为Isp，含有半胱氨酸和组氨酸依赖性的 酰胺水解酶/肽酶（acetylglucosaminidase）结构域和乙酰氨基葡糖苷酶结构域。StcB和ISP的管理 通过Rgg 2/3群体感应途径导致细菌细胞表面的显著变化， 导致与纤连蛋白和上皮细胞的不同附着，以及不同的免疫- 调节活性。本提案旨在阐明StcB和Isp 酶解释了S表面的生化变化。化脓，这些变化如何导致 表面结构和蛋白质的差异活性，以及这些变化如何影响S. 化脓性细菌在宿主中定植并调节免疫活性。

Project Summary/Abstract Little is understood about the physiological or regulatory factors of Streptococcus pyogenes that enable switching between its commensal-like and virulent states. This proposal describes experimental approaches that seek to continue defining and characterizing quorum-sensing regulatory pathways that correspond to phenotypes consistent with the avirulent lifestyle of Streptococcus pyogenes (Group A Streptococcus; GAS). The quorum sensing network in Streptococcus pyogenes utilizing short hydrophobic peptide (SHP) pheromones and the pheromone receptors Rgg2 and Rgg3 regulates several phenotypes, including biofilm development, cell aggregation, aminoglycoside susceptibility, and lysozyme resistance, by an unknown mechanism. Our studies indicate that each of these phenotypes depend upon the expression of a small protein of unknown function. We hypothesize that this protein, referred to as StcB, is an inhibitor of an enzyme(s) that targets peptidoglycan bonds of the cell wall. Additional studies indicate the target of StcB is a murein hydrolase enzyme, called Isp, that contains cysteine and histidine-dependent amidohydrolase/peptidase (CHAP) and acetylglucosaminidase domains. Governance of StcB and Isp by the Rgg2/3 quorum sensing pathway accounts for significant changes to the bacterial cell surface, resulting in differential attachment to fibronectin and epithelial cells, and differential immuno- modulatory activities. This proposal seeks to elucidate the mechanisms by which StcB and Isp enzymes account for biochemical changes to the surface of S. pyogenes, how these changes lead to differential activity of surface structures and proteins, and how these changes affect the ability of S. pyogenes to colonize the host and modulate immune activities.