Signal-independent activation reveals two-component regulatory networks.
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ABSTRACT:
ORGANISM(S): Streptococcus agalactiae
PROVIDER: GSE261394 | GEO | 2024/03/25
REPOSITORIES: GEO
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Project description:In bacterial two-component regulatory systems (TCSs), dephosphorylation of phosphorylated response regulator is essential for resetting the activated systems to the pre-activation state. However, in the SaeRS TCS, a major virulence TCS of Staphylococcus aureus, the mechanism for dephosphorylation of the response regulator SaeR has not been identified. Here we report that two auxiliary proteins from the sae operon, SaeP and SaeQ, form a ternary complex with the sensor kinase SaeS and activate the sensor kinase’s phosphatase activity. Efficient activation of the phosphatase activity of SaeS required the presence of both SaeP and SaeQ. When SaeP and SaeQ were expressed, the expression of coagulase, a sae target with low affinity to phosphorylated SaeR, was greatly reduced, while the expression of alpha-hemolysin, a sae target with high affinity to phosphorylated SaeR, was not, demonstrating a differential effect of SaePQ on sae target gene expression. When expression of SaePQ was abolished, most sae target genes were induced at an elevated level. Since the expression of SaeP and SaeQ is induced by SaeRS TCS, these results suggest that the SaeRS TCS returns to pre-activation state by a negative feedback mechanism. To examine the global effect of SaePQ on sae target gene expression, we treated the wild type strain of USA300-P23 and its P1 promoter mutant with HNP-1 and analyzed the transcription of sae target genes by microarray assays. WT and P1 cells were compared against a each other at the same time point and against a T=0 reference.
2012-03-09 | E-GEOD-36230 | biostudies-arrayexpress
Project description:In bacterial two-component regulatory systems (TCSs), dephosphorylation of phosphorylated response regulator is essential for resetting the activated systems to the pre-activation state. However, in the SaeRS TCS, a major virulence TCS of Staphylococcus aureus, the mechanism for dephosphorylation of the response regulator SaeR has not been identified. Here we report that two auxiliary proteins from the sae operon, SaeP and SaeQ, form a ternary complex with the sensor kinase SaeS and activate the sensor kinase’s phosphatase activity. Efficient activation of the phosphatase activity of SaeS required the presence of both SaeP and SaeQ. When SaeP and SaeQ were expressed, the expression of coagulase, a sae target with low affinity to phosphorylated SaeR, was greatly reduced, while the expression of alpha-hemolysin, a sae target with high affinity to phosphorylated SaeR, was not, demonstrating a differential effect of SaePQ on sae target gene expression. When expression of SaePQ was abolished, most sae target genes were induced at an elevated level. Since the expression of SaeP and SaeQ is induced by SaeRS TCS, these results suggest that the SaeRS TCS returns to pre-activation state by a negative feedback mechanism.
2012-03-09 | GSE36230 | GEO
Project description:Staphylococcus aureus is a Gram-positive opportunistic pathogen, which is carried by approximately 30 % of the population at any time. In addition to being a commensal S. aureus can cause an array of infections, ranging from mild skin and soft tissue infections to life threatening endocarditis and septicemia. S. aureus encodes a variety of virulence factors that facilitate its pathogenic lifestyle. Genes encoding these virulence factors are under tight control by a complex regulatory network, which includes, sigma factors, sRNAs, and protein-based systems, such as Two-Component Systems (TCS). Previous work in our lab demonstrated that overexpression of the sRNA tsr37 leads to an increase in cellular aggregation in the absence of host serum. We determined that the clumping phenotype was dependent on a previously unannotated 88 amino acid protein encoded within the tsr37 sRNA transcript (which we named ScrA for S. aureus clumping regulator A). In addition to increased clumping, overexpression of ScrA also leads to increased biofilm formation. To investigate the mechanism of action of ScrA we performed mass spectrometry proteomics and RNA-sequencing in the ScrA overexpressing strain. A variety of virulence factors, including several surface adhesins were upregulated while several proteases were downregulated. Moreover, results showed a significant upregulation of the SaeRS two component system, suggesting that ScrA is influencing SaeRS activity. We go on to demonstrate that overexpression of ScrA in a saeR mutant abrogates the clumping/biofilm phenotypes confirming that ScrA functions via the Sae system. Finally, we identified the ArlRS TCS as a potential positive regulator of scrA expression. Collectively our results show that ScrA is an activator of the SaeRS system and suggests that ScrA may act as an intermediary between the ArlRS and SaeRS systems.
2022-08-11 | PXD028409 | Pride
Project description:Group B Streptococcus (GBS) is a pathobiont responsible for invasive infections in neonates and in the elderly. The transition from a commensal to an invasive pathogen relies on the timely regulation of a set of virulence factors. In this study, we characterized the role of the SaeRS two-component system in GBS pathogenesis. Loss-of-function mutations in the SaeR response regulator decrease virulence in mouse models of invasive infection . Transcriptome and in vivo analysis reveal a regulatory system specifically activated during infection to control the expression of only two virulence factors: the PbsP adhesin and the BvaP secreted protein. The in vivo surge in SaeRS-regulated genes is complemented by fine-tuning mediated by the repressor of virulence CovRS system to establish a coordinated response. Constitutive activation of the SaeRS regulatory pathway increases adhesion and invasion of epithelial and endothelial barriers, though at the cost of reduced virulence. In conclusion, SaeRS is a specialized and dynamic system that balances the invasion of host barriers with disease progression.
2024-07-10 | GSE269249 | GEO
Project description:Staphylococcus aureus is a Gram-positive opportunistic pathogen, which is carried by approximately 30 % of the population at any time. In addition to being a commensal S. aureus can cause an array of infections, ranging from mild skin and soft tissue infections to life threatening endocarditis and septicemia. S. aureus encodes a variety of virulence factors that facilitate its pathogenic lifestyle. Genes encoding these virulence factors are under tight control by a complex regulatory network, which includes, sigma factors, sRNAs, and protein-based systems, such as Two-Component Systems (TCS). Previous work in our lab demonstrated that overexpression of the sRNA tsr37 leads to an increase in cellular aggregation in the absence of host serum. We determined that the clumping phenotype was dependent on a previously unannotated 88 amino acid protein encoded within the tsr37 sRNA transcript (which we named ScrA for S. aureus clumping regulator A). In addition to increased clumping, overexpression of ScrA also leads to increased biofilm formation. To investigate the mechanism of action of ScrA we performed mass spectrometry proteomics and RNA-sequencing in the ScrA overexpressing strain. A variety of virulence factors, including several surface adhesins were upregulated while several proteases were downregulated. Moreover, results showed a significant upregulation of the SaeRS two component system, suggesting that ScrA is influencing SaeRS activity. We go on to demonstrate that overexpression of ScrA in a saeR mutant abrogates the clumping/biofilm phenotypes confirming that ScrA functions via the Sae system. Finally, we identified the ArlRS TCS as a potential positive regulator of scrA expression. Collectively our results show that ScrA is an activator of the SaeRS system and suggests that ScrA may act as an intermediary between the ArlRS and SaeRS systems.
2021-10-01 | GSE184753 | GEO
Project description:Background: Staphylococcus epidermidis (SE) has emerged as one of the most important causes of nosocomial infections. The SaeRS two-component signal transduction system (TCS) influences virulence and biofilm formation in Staphylococcus aureus. The deletion of saeR in S. epidermidis results in impaired anaerobic growth and decreased nitrate utilization. However, the regulatory function of SaeRS on biofilm formation and autolysis in S. epidermidis remains unclear. Results: The saeRS genes of SE1457 were deleted by homologous recombination. The saeRS deletion mutant, SE1457DsaeRS, exhibited increased biofilm formation that was disturbed more severely (a 4-fold reduction) by DNase I treatment compared to SE1457 and the complementation strain SE1457saec. Compared to SE1457 and SE1457saec, SE1457DsaeRS showed increased Triton X-100-induced autolysis (approximately 3-fold) and decreased cell viability in planktonic/biofilm states; further, SE1457DsaeRS also released more extracellular DNA (eDNA) in the biofilms. Correlated with the increased autolysis phenotype, the transcription of autolysis-related genes, such as atlE and aae, was increased in SE1457DsaeRS. Whereas the expression of accumulation-associated protein was up-regulated by 1.8-fold in 1457DsaeRS, the expression of an N-acetylglucosaminyl transferase enzyme (encoded by icaA) critical for polysaccharide intercellular adhesion (PIA) synthesis was not affected by the deletion of saeRS. Conclusions: Deletion of saeRS in S. epidermidis resulted in an increase in biofilm-forming ability, which was associated with increased eDNA release and up-regulated Aap expression. The increased eDNA release from SE1457DsaeRS was associated with increased bacterial autolysis and decreased bacterial cell viability in the planktonic/biofilm states. Comparision between SE1457 wild type strain and SA1457 SaeRS mutant strain after 4 hours and 12 hours of growth
2012-01-12 | E-GEOD-29309 | biostudies-arrayexpress
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) can colonize the human vaginal tract leading to both superficial and serious infections in adults and neonates. To study bacterial colonization of the reproductive tract in a mammalian system, we employed a murine vaginal carriage model. Using RNASeq, the transcriptome of GBS growing in vivo during vaginal carriage was determined. Over one-quarter of the genes in GBS were found to be differentially regulated during in vivo colonization as compared to laboratory cultures. A two-component system (TCS) homologous to the staphylococcal virulence regulator SaeRS was identified as being up-regulated in vivo. One of the SaeRS targets, pbsP, a proposed GBS vaccine candidate, was shown to be important for colonization of the vaginal tract. A component of vaginal lavage fluid acted as a signal to turn on pbsP expression via SaeRS. These data demonstrate the ability to quantify RNA expression directly from the murine vaginal tract and identify novel genes involved in vaginal colonization by GBS. They also provide more information about the regulation of an important virulence and colonization factor of GBS, pbsP, by the TCS SaeRS.
2018-02-06 | GSE109680 | 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:Background: Staphylococcus epidermidis (SE) has emerged as one of the most important causes of nosocomial infections. The SaeRS two-component signal transduction system (TCS) influences virulence and biofilm formation in Staphylococcus aureus. The deletion of saeR in S. epidermidis results in impaired anaerobic growth and decreased nitrate utilization. However, the regulatory function of SaeRS on biofilm formation and autolysis in S. epidermidis remains unclear. Results: The saeRS genes of SE1457 were deleted by homologous recombination. The saeRS deletion mutant, SE1457DsaeRS, exhibited increased biofilm formation that was disturbed more severely (a 4-fold reduction) by DNase I treatment compared to SE1457 and the complementation strain SE1457saec. Compared to SE1457 and SE1457saec, SE1457DsaeRS showed increased Triton X-100-induced autolysis (approximately 3-fold) and decreased cell viability in planktonic/biofilm states; further, SE1457DsaeRS also released more extracellular DNA (eDNA) in the biofilms. Correlated with the increased autolysis phenotype, the transcription of autolysis-related genes, such as atlE and aae, was increased in SE1457DsaeRS. Whereas the expression of accumulation-associated protein was up-regulated by 1.8-fold in 1457DsaeRS, the expression of an N-acetylglucosaminyl transferase enzyme (encoded by icaA) critical for polysaccharide intercellular adhesion (PIA) synthesis was not affected by the deletion of saeRS. Conclusions: Deletion of saeRS in S. epidermidis resulted in an increase in biofilm-forming ability, which was associated with increased eDNA release and up-regulated Aap expression. The increased eDNA release from SE1457DsaeRS was associated with increased bacterial autolysis and decreased bacterial cell viability in the planktonic/biofilm states.
2012-01-12 | GSE29309 | GEO