Transcriptome analysis of Streptococcus mutans quorum sensing-mediated persisters reveals an enrichment in genes related to stress-defense mechanisms
Persisters are a small fraction of growth-arrested phenotypic variants that can survive lethal concentrations of antibiotics but are able to resume growth once antibiotics are stopped. Their formation can be a stochastic process or triggered by environmental cues. In the human pathogen Streptococcus mutans, the canonical peptide-based quorum sensing system is an inducible DNA repair system that is pivotal for bacterial survival. Previous work showed that the CSP signaling peptide is a stress-signaling alarmone that promotes the formation of stress-induced persisters. In this study, we exposed S. mutans to the CSP pheromone to mimic DNA damage conditions and isolated the antibiotic persisters by treating the cultures with ofloxacin. Transcriptome analysis was then performed to evaluate the differential gene expression between the normal stationary phase cells and the persisters. RNA-sequencing revealed that triggered persistence was associated with the up-regulation of genes related to several stress-defense mechanisms, notably, multidrug efflux pumps, the arginine deaminase pathway, and the Opu/Opc system. In addition, we showed that inactivation of the VicK kinase of the YycFG essential two-component regulatory system abolished the formation of triggered persisters via the CSP pheromone. These data contribute to the understanding of the triggered persistence phenotype and may suggest new therapeutic strategies for treating persistent streptococcal infections Overall design: The formation of S. mutans persisters was triggered with a pre-incubation with the CSP quorum sensing pheromone. Persisters were then isolated using the ofloxacin antibiotic. The gene expression profiling of the persisters was compared to the one of CSP-induced untreated cells.