Intercellular Communication and Pheromone Maturation in Gram-Positive Bacteria.

项目摘要 革兰氏阳性细菌处理和释放小肽，或“信息素”，作为关键信号作用于 适应性特征的诱导，包括那些与毒力有关的特征。一类小的信号信息素是 环状自我诱导肽(AIP)，它调节协调毒力和 葡萄球菌、李斯特菌、梭状芽胞杆菌和肠球菌的持久性。循环AIP生产中的缺陷和 信号可以损害这些微生物的毒力特征，强调了基于多肽的相关性 健康和疾病的信号。金黄色葡萄球菌含有一种环肽信号系统，称为 辅助基因调控(AGR)系统。这个“群体感应”系统依赖于合成， 加工和出口环状AIP，来自其前体蛋白AGRG D，用于功能。AIP信令 通过AGR导致金黄色葡萄球菌毒力因子的产生，而信号的中断导致 在皮肤和肺部感染模型中显著减弱。尽管AGR和金黄色葡萄球菌之间存在明显的联系 病理生物学方面，我们对AIP生物合成机制的认识存在很大差距。最值得注意的是：(I) AIP的多肽加工所需的蛋白质尚未阐明；(Ii)AIP或其转运体 先导肽尚未被鉴定；(Iii)AIP变异体的差异加工尚未被研究； 以及(Iv)细菌物种之间的环肽加工事件中的保守性尚不清楚。在这笔赠款中， 我们提供了与我们在金黄色葡萄球菌中发现的一种推定的多肽酶MroQ相关的数据，我们假设该酶有作用 直接或间接影响AGR系统组件，以促进加工和/或出口的最后步骤 AIP。这项资助的总体目标是询问以前未知的环肽的机制。 金黄色葡萄球菌的成熟，为革兰氏阳性菌潜在的功能保守提供了洞察力 病原体。目标1将定义MroQ如何促进AIP处理、导出或两者兼而有之。目标2将审问 MroQ与AGR系统或其他膜组件相互作用的程度，并将利用生物化学 测试MroQ是否直接切割AGRGD。目标3将确定MroQ促进AGR活性的程度 物种内和其他物种之间的变异，并识别 口述MroQ的特异性。

Project Summary Gram-positive bacteria process and release small peptides, or “pheromones”, that act as critical signals for the induction of adaptive traits including those involved in virulence. One class of small signaling pheromones is the cyclic auto-inducing peptide (AIP), which regulates the expression of genes that orchestrate virulence and persistence in Staphylococci, Listeria, Clostridia, and Enterococci. Defects in cyclic AIP production and signaling can compromise virulence traits of these microbes, underscoring the relevance of peptide-based signaling to health and disease. Staphylococcus aureus harbors a cyclic peptide signaling system known as the accessory gene regulatory (Agr) system. This “quorum sensing” system depends on the synthesis, processing, and export of a cyclic AIP, derived from its precursor protein, AgrD, for function. AIP signaling through Agr leads to the production of S. aureus virulence factors, whereas disruption of signaling causes significant attenuation in skin and lung infection models. Despite clear connections between Agr and S. aureus pathobiology, there exist major gaps in our knowledge of the mechanics of AIP biosynthesis. Most notably: (i) the proteins needed for peptide processing of AIP have not been elucidated; (ii) a transporter for AIP or its leader peptide has not been identified; (iii) differential processing of AIP variants has not been investigated; and (iv) conservation in cyclic peptide processing events between bacterial species is not known. In this grant, we provide data related to our discovery of a putative peptidase in S. aureus, MroQ, that we hypothesize acts directly or indirectly on Agr system components to promote the final steps in the processing and/or export of AIP. The overall goals of this grant are to interrogate the previously unknown mechanics of cyclic peptide maturation in S. aureus and provide insight into the potential conservation of function in Gram positive pathogens. Aim 1 will define how MroQ promotes AIP processing, export, or both. Aim 2 will interrogate the extent with which MroQ interacts with Agr system or other membrane components and will use biochemistry to test if MroQ directly cleaves AgrD. Aim 3 will determine the extent with which MroQ promotes activity of Agr variants both within species and among other species and identify the AgrD sequence characteristics that dictate MroQ specificity.