Perry Julie A, Cvitkovitch Dennis G, Lévesque Céline M
Dental Research Institute, Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario, Canada.
FEMS Microbiol Lett. 2009 Oct;299(2):261-6. doi: 10.1111/j.1574-6968.2009.01758.x. Epub 2009 Aug 18.
Streptococcal competence-stimulating peptides (CSPs) were once thought to passively communicate population density in a process known classically as quorum sensing. However, recent evidence has shown that these peptides may also be inducible 'alarmones,' capable of conveying sophisticated messages in a population including the induction of altruistic cellular suicide under stressful conditions. We have previously characterized the alarmone response in Streptococcus mutans, a cariogenic resident of the oral flora, in which a novel bacteriocin-like peptide causes cell death in a subset of the population. Our objective in this work was to characterize the mechanism of immunity to cell death in S. mutans. Toward this goal, we have identified the conditions under which immunity is induced, and identified the regulatory system responsible for differential (and protective) expression of immunity. We also showed that CSP-induced death contributes to S. mutans biofilm formation through the release of chromosomal DNA into the extracellular matrix, providing a long sought-after mechanistic explanation for the role of CSP in S. mutans biofilm formation.
链球菌感受态刺激肽（CSPs）曾被认为在一个经典的群体感应过程中被动地传递群体密度信息。然而，最近的证据表明，这些肽也可能是可诱导的“警报素”，能够在群体中传递复杂的信息，包括在压力条件下诱导利他性细胞自杀。我们之前已经对变形链球菌（一种口腔菌群中的致龋菌）中的警报素反应进行了表征，其中一种新型的类细菌素肽会导致群体中的一部分细胞死亡。我们这项工作的目标是表征变形链球菌中细胞死亡免疫机制。为了实现这一目标，我们确定了诱导免疫的条件，并确定了负责免疫差异（和保护性）表达的调节系统。我们还表明，CSP诱导的死亡通过将染色体DNA释放到细胞外基质中促进了变形链球菌生物膜的形成，为CSP在变形链球菌生物膜形成中的作用提供了长期以来寻求的机制解释。
