Molecular singularities in a pheromone sensor triumvirate desynchronize the competence-predation interplay in the human commensal Streptococcus salivarius
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PROVIDER: PRJNA493819 | ENA |
REPOSITORIES: ENA
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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: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: Not available
| S-EPMC6703854 | biostudies-literature
Project description:The CovR environmental sensor orchestrates competence bimodality in salivarius streptococci
| PRJNA665491 | ENA
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:Candida albicans can stochastically switch between two phenotypes, white and opaque. Opaque cells are the sexually competent form of C. albicans and therefore undergo efficient polarized growth and mating in the presence of pheromone. In contrast, white cells cannot mate, but are induced - under a specialized set of conditions - to form biofilms in response to pheromone. In this work, we compare the genetic regulation of such "pheromone-stimulated" biofilms with that of "conventional" C. albicans biofilms. In particular, we examined a network of six transcriptional regulators (Bcr1, Brg1, Efg1, Tec1, Ndt80, and Rob1) that mediate conventional biofilm formation for their potential roles in pheromone-stimulated biofilm formation. We show that four of the six transcription factors (Bcr1, Brg1, Rob1, and Tec1) promote formation of both conventional and pheromone-stimulated biofilms, indicating they play general roles in cell cohesion and biofilm development. In addition, we identify the master transcriptional regulator of pheromone-stimulated biofilms as C. albicans Cph1, ortholog of Saccharomyces cerevisiae Ste12. Cph1 regulates mating in C. albicans opaque cells, and here we show that Cph1 is also essential for pheromone-stimulated biofilm formation in white cells. In contrast, Cph1 is dispensable for the formation of conventional biofilms. The regulation of pheromone- stimulated biofilm formation was further investigated by transcriptional profiling and genetic analyses. These studies identified 206 genes that are induced by pheromone signaling during biofilm formation. One of these genes, HGC1, is shown to be required for both conventional and pheromone-stimulated biofilm formation. Taken together, these observations compare and contrast the regulation of conventional and pheromone-stimulated biofilm formation in C. albicans, and demonstrate that Cph1 is required for the latter, but not the former.
2013-02-22 | GSE44449 | GEO
Project description:In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-beta-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposure to alarm pheromone in aphid colonies raised on transgenic Arabidopsis thaliana plants that produce EBF leads to habituation of the aphid population. Whereas naïve aphids are repelled by EBF, habituated aphids show no avoidance response. Individual aphids from the habituated colony can revert back to being EBF-sensitive in three generations, indicating that this behavioral change is not caused by a genetic mutation. Instead, DNA microarray experiments comparing gene expression in naïve and habituated aphids treated with EBF demonstrate an almost complete desensitization in the transcriptional response to EBF. Furthermore, EBF-responsive aphids, but not habituated aphids show significantly lower reproduction in the presence of EBF. Although both naïve and habituated aphids emit EBF upon damage, EBF-responsive aphids display a higher survival rate in the presence of coccinellid predators and thus outperform habituated aphids that do not show an avoidance response. These results provide direct evidence that aphid perception of conspecific alarm pheromone aids in predator avoidance and thereby bestows fitness benefits in survivorship and fecundity. Although habituated M. persicae have equal fecundity on control and EBF-producing plants, such transgenics may have practical applications in agriculture because of increased predation of habituated aphids. Log fold-changes (LogFC) were computed and contigs with P-values ≤ 0.05 were considered to be differentially expressed (see Supplementary file at foot of this record).
2010-03-01 | GSE20445 | GEO
Project description:In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-beta-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposure to alarm pheromone in aphid colonies raised on transgenic Arabidopsis thaliana plants that produce EBF leads to habituation of the aphid population. Whereas naïve aphids are repelled by EBF, habituated aphids show no avoidance response. Individual aphids from the habituated colony can revert back to being EBF-sensitive in three generations, indicating that this behavioral change is not caused by a genetic mutation. Instead, DNA microarray experiments comparing gene expression in naïve and habituated aphids treated with EBF demonstrate an almost complete desensitization in the transcriptional response to EBF. Furthermore, EBF-responsive aphids, but not habituated aphids show significantly lower reproduction in the presence of EBF. Although both naïve and habituated aphids emit EBF upon damage, EBF-responsive aphids display a higher survival rate in the presence of coccinellid predators and thus outperform habituated aphids that do not show an avoidance response. These results provide direct evidence that aphid perception of conspecific alarm pheromone aids in predator avoidance and thereby bestows fitness benefits in survivorship and fecundity. Although habituated M. persicae have equal fecundity on control and EBF-producing plants, such transgenics may have practical applications in agriculture because of increased predation of habituated aphids. Log fold-changes (LogFC) were computed and contigs with P-values ≤ 0.05 were considered to be differentially expressed (see Supplementary file at foot of this record). Agilent 8x15K array previously reported by Ramsey et al., 2007 - BMC Genomics 8: 243. Two-condition experiment using Alexa Fluor 555 and 647 dyes. Biological replicates: 4 control replicates, 4 treated replicates.
2010-02-28 | E-GEOD-20445 | biostudies-arrayexpress
Project description:Candida albicans can stochastically switch between two phenotypes, white and opaque. Opaque cells are the sexually competent form of C. albicans and therefore undergo efficient polarized growth and mating in the presence of pheromone. In contrast, white cells cannot mate, but are induced - under a specialized set of conditions - to form biofilms in response to pheromone. In this work, we compare the genetic regulation of such "pheromone-stimulated" biofilms with that of "conventional" C. albicans biofilms. In particular, we examined a network of six transcriptional regulators (Bcr1, Brg1, Efg1, Tec1, Ndt80, and Rob1) that mediate conventional biofilm formation for their potential roles in pheromone-stimulated biofilm formation. We show that four of the six transcription factors (Bcr1, Brg1, Rob1, and Tec1) promote formation of both conventional and pheromone-stimulated biofilms, indicating they play general roles in cell cohesion and biofilm development. In addition, we identify the master transcriptional regulator of pheromone-stimulated biofilms as C. albicans Cph1, ortholog of Saccharomyces cerevisiae Ste12. Cph1 regulates mating in C. albicans opaque cells, and here we show that Cph1 is also essential for pheromone-stimulated biofilm formation in white cells. In contrast, Cph1 is dispensable for the formation of conventional biofilms. The regulation of pheromone- stimulated biofilm formation was further investigated by transcriptional profiling and genetic analyses. These studies identified 206 genes that are induced by pheromone signaling during biofilm formation. One of these genes, HGC1, is shown to be required for both conventional and pheromone-stimulated biofilm formation. Taken together, these observations compare and contrast the regulation of conventional and pheromone-stimulated biofilm formation in C. albicans, and demonstrate that Cph1 is required for the latter, but not the former. 4 condition experiment: white and opaque cells in planktonic and pheromone-induced biofilm conditions with and without alpha pheromone. WT strain (P37005), the tec1 mutant strain and the cph1 mutant strain
2013-02-22 | E-GEOD-44449 | biostudies-arrayexpress
Project description:Comparison of P. putida type strain crude extract with P. putida type strain phenotype evading myxobacterium C. ferrugineus predation.
2021-01-21 | MSV000086742 | MassIVE