Dataset Information

A genome-wide CRISPRi screen reveals a StkP-mediated connection between cell-wall integrity and competence in Streptococcus salivarius

ABSTRACT: Synchronizing production of antibacterial compounds and integration of DNA released by dead cells, competence is one of the most efficient bacterial evolutionary and adaptative strategies. In most streptococci, this tactic is orchestrated by the ComRS system, a pheromone communication device providing competence bimodal initiation and sharp time window of activation. Understanding how this developmental process integrates multiple inputs to fine-tune the adequate response is a long-standing question. Actually, essential genes involved in the regulation of ComRS have been challenging to study. In this work, we built a conditional mutant library using the CRISPR-interference technology and developed three complementary screens to investigate competence genetic regulation in the human commensal Streptococus salivarius. We highlighted that competence increases upon cell-wall impairment, suggesting a connection between cell envelope stress and competence activation. Notably, we report the key role played by StkP, a serine-threonine kinase known to regulate cell-wall assembly. We showed that StkP controls competence by a mechanism responding to peptidoglycan fragments. Together, those data suggest a key cell-wall sensing mechanism coupling competence to cell envelope integrity.

ORGANISM(S): Streptococcus salivarius

PROVIDER: GSE204976 | GEO | 2022/08/25

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:In bacteria, phenotypic heterogeneity rescues the need for diversity in isogenic populations and allow concomitant multiple survival strategies when choosing only one is too risky. This powerful tactic is exploited for competence in streptococci and results in a bimodal activation, where only a subset of the community triggers the system. Deciphering the mechanisms underlying this puzzling behavior has remained challenging, especially since its study has been mainly achieved in S. mutans, where two different but interconnected regulation networks control competence. In this work, we sought to determine the origin of bimodality associated to the ComRS system thanks to the simplified S. salivarius model that harbors no supplemental signaling system. Using a single cell fluorescence reporter system together with the overexpression of the main actors of the regulation network, we showed that the ComR intracellular concentration is directly linked to the proportion of competent cells in the population. We report that this type of activation requires a functional positive feedback loop acting on comS through Opp and a putative ComS exporter, PptAB. To determine the origin of the heterogeneity amplified by the loop, we developed a mathematical model suggesting that either noise on ComS or ComR abundance could explain bimodality. Because ComR abundance is central for competence bimodal activation, we conducted an in silico identification and a systematic deletion of all the Two Component Systems (TCS) present in S. salivarius and identified CovRS, a well described virulence regulator in GAS and GBS, as a repressor of comR transcription. In vitro direct binding of CovR with the promoter of comR and transcriptomics confirmed those data. As CovRS integrates environmental stimuli that control ComR intracellular concentration, it represents the missing puzzle piece bridging environmental conditions and competence (bimodal) activation in salivarius streptococci.

Dataset Information

A genome-wide CRISPRi screen reveals a StkP-mediated connection between cell-wall integrity and competence in Streptococcus salivarius

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure