Intercellular Communication and Pheromone Maturation in Gram-Positive Bacteria.

项目摘要 革兰氏阳性菌加工并释放小肽或“信息素”，其充当革兰氏阳性菌的关键信号。 诱导适应性特征，包括与毒力相关的特征。一类小信号信息素是 环自诱导肽（AIP），它调节基因的表达，协调毒力和 在葡萄球菌、李斯特菌、梭菌和肠球菌中的持久性。循环AIP生产中的缺陷和 信号传导可以损害这些微生物的毒力特性，强调了基于肽的 健康和疾病的信号。金黄色葡萄球菌含有一个称为环肽信号系统， 辅助基因调控系统（Agr）。这种“群体感应”系统依赖于合成， 加工和输出源自其前体蛋白AgrD的环状AIP以发挥功能。AIP信令 通过Agr导致S.金黄色葡萄球菌毒力因子，而信号转导的破坏导致 在皮肤和肺部感染模型中显著衰减。尽管Agr和S.金黄色 尽管AIP在病理生物学上有很大的优势，但我们对AIP生物合成机制的认识存在重大空白。最值得注意的是：（一） AIP的肽加工所需的蛋白质尚未阐明;（ii）AIP的转运蛋白或其 尚未鉴定前导肽;（iii）尚未研究AIP变体的差异加工; 和（iv）细菌物种之间环肽加工事件的保守性是未知的。在这份补助金中， 我们提供了与我们在S. aureus，MroQ，我们假设行为 直接或间接地对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研究以前未知的环肽机制 S.金黄色葡萄球菌，并提供了对革兰氏阳性菌功能的潜在保护的见解。 病原体目标1将定义MroQ如何促进AIP处理、出口或两者兼而有之。目标2将询问 MroQ与Agr系统或其他膜组件相互作用的程度，并将使用生物化学， 测试MroQ是否直接切割AgrD。目的3将确定MroQ促进Agr活性的程度 在物种内和其他物种之间的变体，并鉴定AgrD序列特征， 决定MroQ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.