A genome-wide CRISPRi screen reveals a StkP-mediated connection between cell-wall integrity and competence in Streptococcus salivarius
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PROVIDER: PRJNA842940 | ENA |
REPOSITORIES: ENA
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Project description: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.
2022-08-25 | GSE204976 | GEO
Project description:Small distortions in transcriptional networks might lead to drastic phenotypical changes, especially in cellular developmental programs such as competence for natural transformation. Here, we report a pervasive circuitry rewiring for competence and predation interplay in commensal streptococci. Canonically, in model species of streptococci such as Streptococcus pneumoniae and Streptococcus mutans, the pheromone-based two-component system BlpRH is a central node that orchestrates the production of antimicrobial compounds (bacteriocins) and incorporates signal from the competence activation cascade. However, the human commensal Streptococcus salivarius does not contain a functional BlpRH pair and in this species, the competence signaling system ComRS directly couples bacteriocin production and competence commitment. This network shortcut might account for an optimal reaction against microbial competitors and could explain the high prevalence of S. salivarius in the human digestive tract. Moreover, the broad spectrum of bacteriocin activity against pathogenic bacteria showcases the commensal and genetically tractable S. salivarius species as a user-friendly model for natural transformation and bacterial predation.
2018-01-10 | GSE100416 | GEO
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.
2021-01-31 | GSE158512 | GEO
Project description:The human oral cavity is one of the most competing environments, considering the extent and diversity of the bacterial community that colonizes it, as well as the multiple stresses to which it is subjected. The commensal species Streptococcus salivarius is one of the first colonizers of the oral mucosa (tongue, gums, inner cheeks and tooth enamel) in infants and remains predominant throughout the life of an adult. In order to adapt to diverse and variable environmental conditions, S. salivarius triggers in a coordinated way two bacterial developmental processes: competence (acquisition of extracellular DNA and new genetic traits) and predation (secretion of cytotoxic molecule), via ComR, a transcription factor activatable by a "pheromone" peptide. Nevertheless, the activation of other transcriptional regulators can uncouple these 2 mechanisms to allow, for example, only the production of toxins without triggering the competence phase.
2019-08-19 | GSE120640 | GEO
Project description:The CovR environmental sensor orchestrates competence bimodality in salivarius streptococci
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Project description:To investigate the subspecies level differences in the expression profiles of Streptococcus salivarius strains, we conducted the RNA sequencing analysis of Streptococcus salivarius strains.
2024-11-10 | GSE278791 | GEO
Project description:Circuitry rewiring directly couples competence to predation in the gut-dweller Streptococcus salivarius
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Project description:Lactobacillus salivarius, found in the intestinal microbiota of humans and animals, is studied as an example of sub-dominant intestinal commensals that may impart benefits upon their host. Strains typically harbor at least one megaplasmid which encodes functions contributing to contingency metabolism and environmental adaptation. RNA-seq transcriptomic analysis of L. salivarius strain UCC118 identified the presence of a novel long and unusually abundant non-coding RNA (lancRNA) encoded by the megaplasmid and which represented more than 75% of total RNA-seq reads after depletion of ribosomal RNA species. The expression level of this 550 nt lancRNA in L. salivarius UCC118 exceeded that of the 16S rRNA, it accumulated during growth, was very stable over time, and was also expressed during intestinal transit in a mouse. This lancRNA sequence is specific to the L. salivarius species, however among 45 L. salivarius genomes analyzed, not all (only 34) harbored the sequence for the lancRNA. This lancRNA was produced in 27 tested L. salivarius strains but at strain-specific expression levels. High-level lancRNA expression correlated with high megaplasmid copy number. Transcriptome analysis of a deletion mutant lacking this lancRNA identified altered expression levels of genes in a number of pathways but a definitive function of this new long non-coding RNA was not identified. This lancRNA presents distinctive and unique properties, and suggests potential basic and applied scientific developments of this phenomenon.
2017-08-01 | GSE92837 | GEO
Project description:Identification of proteins from extracellular vesicles isolated from Streptococcus salivarius. This work was financially supported by the National Science Centre, Poland (grant number 2021/43/D/NZ6/01464).
2023-05-24 | PXD039138 | Pride
Project description:Porcine bile induced transcriptome of Lactobacillus salivarius
2009-07-16 | E-MEXP-2224 | biostudies-arrayexpress