Coordinated regulation of osmotic imbalance by c-di-AMP shapes ß-lactam tolerance in Group B Streptococcus
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PROVIDER: PRJNA1090533 | ENA |
REPOSITORIES: ENA
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Project description:Streptococcus agalactiae is among the few pathogens that have not developed resistance to ß-lactam antibiotics despite decades of clinical use. The molecular basis of this long-lasting susceptibility has not been investigated, and it is uncertain whether specific mechanisms constraint the emergence of resistance. In this study, we first report a conserved role of the signaling nucleotide cyclic-di-AMP in the sensitivity of S. agalactiae to ß-lactam. Specifically, we demonstrate that inactivation of the phosphodiesterase GdpP confers ß-lactam tolerance. Characterizing the signaling pathway revealed an antagonistic regulation by the transcriptional factor BusR, which is activated by c-di-AMP and negatively regulates ß-lactam susceptibility. Furthermore, we show that simultaneous inhibition of osmolyte transporters activity and transcription by c-di-AMP has an additive effect, sustaining ß-lactam tolerance. Finally, transposon mutagenesis for ß-lactam reduced susceptibility reveals a convergent pattern of mutations, including in the KhpAB small RNA chaperone and the protein S immunomodulator. Overall, our findings suggest mechanisms that may foster antibiotic resistance in S. agalactiae and demonstrate that c-di-AMP acts as a turgor pressure rheostat, coordinating an integrated response to cell wall weakening due to ß-lactam activity.
2024-04-25 | GSE262190 | GEO
Project description:This study investigated the transcriptomic response of rice pathogen Acidovorax avenae subsp. avenae (Aaa) strain RS-1 to ß-lactam antibiotics in particular Ampicillin (Amp) and the result highlights the importance of Amp-induced differentially expressed genes in the virulence of Aaa strain RS-1.
2017-02-10 | GSE68734 | GEO
Project description:The transcriptional regulator AmpR controls expression of the AmpC ß-lactamase in P. aeruginosa and other bacteria. Studies have demonstrated that in addition to regulating ampC expression, AmpR also regulates the expression of the sigma factor AlgT/U and the production of some quorum-sensing regulated virulence factors. In order to understand the ampR regulon, we compared the expression profiles of PAO1 and its isogenic ampR mutant, PAO∆ampR in the presence and absence of sub-MIC ß-lactam stress. The analysis demonstrates that the ampR regulon is much more extensive than previously thought, with the deletion of ampR affecting the expression of over 300 genes. Expression of an additional 207 genes are affected by AmpR when the cells are exposed to sub-MIC ß-lactam stress, indicating that the ampR regulon in P. aeruginosa is much more extensive than previously thought. An inframe deletion of ampR was generated in P. aeruginosa PAO1. The wild type and ampR mutant strains were grown to mid-log phase and subjected to sub-MIC ß-lactam exposure. Total RNA was isolated from 2-hour ß-lactam exposed and unexposed cells to monitor changes in gene expression arising due to loss of ampR in the presence and absence of ß-lactam exposure.
2012-03-29 | E-GEOD-33188 | biostudies-arrayexpress
Project description:The transcriptional regulator AmpR controls expression of the AmpC ß-lactamase in P. aeruginosa and other bacteria. Studies have demonstrated that in addition to regulating ampC expression, AmpR also regulates the expression of the sigma factor AlgT/U and the production of some quorum-sensing regulated virulence factors. In order to understand the ampR regulon, we compared the expression profiles of PAO1 and its isogenic ampR mutant, PAO∆ampR in the presence and absence of sub-MIC ß-lactam stress. The analysis demonstrates that the ampR regulon is much more extensive than previously thought, with the deletion of ampR affecting the expression of over 300 genes. Expression of an additional 207 genes are affected by AmpR when the cells are exposed to sub-MIC ß-lactam stress, indicating that the ampR regulon in P. aeruginosa is much more extensive than previously thought.
2012-03-30 | GSE33188 | GEO
Project description:C-di-AMP is primarily associated with the regulation of carbon utilization as well as other central traits, central metabolism, and bacterial stringent response to environmental changes. Elevated c-di-AMP levels result in aberrant physiology for most c-di-AMP synthesizing organisms, drawing particular attention to the importance of the c-di-AMP homeostasis and the molecular mechanisms pertaining to nucleotide metabolism and signal transduction. Here we show that c-di-AMP binds the GntR-family regulator DasR, uncovering a direct link between c-di-AMP and GlcNAc signaling. Further, we show c-di-AMP functions as an allosteric activator of DasR activity. GlcNAc is necessary for cell-surface structure from bacteria to humans, as well as a signal for bacterial development and antibiotic production. DasR is a global repressor that oversees GlcNAc metabolism and antibiotic production, which enables Actinobacteria to cope with stress and starvation. Our in vivo studies reveal the important biological role of allosteric regulation by c-di-AMP in metabolic imbalance and the transduction of a series of signals. Notably, DasR also controls intracellular c-di-AMP level through direct repression on disA. Overall, we identify a function of allosteric regulation between c-di-AMP and DasR in global signal integration and c-di-AMP homeostasis in bacteria, which is likely widespread in Actinobacteria.
2024-03-31 | GSE229938 | GEO
Project description:Three types of phenotypic expression of ß-lactam resistance has been reported in MRSA: heterogeneous-, homogeneous-, and Eagle-type resistance. Heterogeneous to homogeneous (hetero-to-homo) conversion of ß-lactam resistance is postulated to be caused by a chromosomal mutation (chr*) together with mecA-gene expression. The Eagle-type resistance is a special pattern of chr* expression in the pre-MRSA strain N315 under the strong mecI-gene mediated repression of mecA gene transcription. Here, for the identification of chr*, experiments were conducted using an in-vitro derived homogeneously imipenem-resistant MRSA strain N315∆IPH5 (∆IPH5). The strain was selected with imipenem 8 mg/L from the heterogeneously imipenem-resistant MRSA strain N315∆IP (∆IP). The whole genome sequencing of ∆IPH5 revealed the presence of a unique mutation in the rpoB gene, rpoB(N967I), causing the amino-acid (AA) substitution of Asp by Ile at the 967th AA position of the RNA polymerase ß subunit. The effect of the mutation on the phenotypic change was confirmed by constructing and studying the phenotype of the strains H5rpoB(I967N), a ∆IPH5-derived strain cured of the rpoB mutation, and N315rpoB(N967I), a N315-derived strain introduced with the mutated rpoB gene. H5rpoB(I967N) regained the hetero-MRSA phenotype, and the mutant strain N315rpoB(N967I) showed an Eagle-type phenotype similar to that of N315h4. Furthermore, subsequent whole genome sequencing revealed that N315h4 also had a missense mutation in the rpoB gene rpoB(R644H). The rpoB mutations caused decreased autolysis, prolonged doubling-time, and tolerance to bactericidal concentrations of methicillin. We concluded that the certain rpoB mutations are chr* responsible for the hetero-to-homo phenotypic conversion of MRSA.
2013-08-27 | GSE42218 | GEO
Project description:Streptococcus pneumoniae harbors two cyclic di-AMP (c-di-AMP) phosphodiesterases Pde1 and Pde2. Previously, we demonstrated that deletion of one or both of these proteins leads to growth retardation in culture media, defects in the bacterial stress response, and attenuation in mouse models of disease. All of these phenotypes are due to increased levels of c-di-AMP, since the nature and break down products of each protein are different, and mutations that lower c-di-AMP levels partially restore growth and stress tolerance in these mutants. However, how c-di-AMP mediates pneumococcal stress resistance and virulence is unknown. To establish how c-di-AMP affects the transcriptome, RNA-Seq analysis was employed to compare gene expression between wild-type and Δpde1Δpde2 (ST2734) pneumococci. Overall, the competence regulon was upregulated in the Δpde1Δpde2 mutant.
2018-04-18 | GSE113231 | GEO
Project description:Cyclic di-AMP is an essential second messenger in many Gram-positive bacteria, including the model organism Bacillus subtilis. Here, we analyzed the transcriptome of a strain accumulating c-di-AMP in vivo. Our results demonstrate that accumulation of c-di-AMP affects the expression of several hundred genes, among them many mother-cell specific sporulation genes. Additionally, the two major biofilm operons, epsA-O and tapA-sipW-tasA, are affected. High levels of c-di-AMP abolish transcription of genes responsible for biofilm formation which in turn leads to a defect in complex colony formation in B. subtilis.
2016-05-25 | GSE79716 | GEO
Project description:Second messenger nucleotides such as c-di-AMP are produced by bacteria in response to environmental stimuli and can contribute to the regulation of a number of cellular processes including osmoregulation, envelope homeostasis, central metabolism, and biofilm formation. Here, as part of an effort to uncover the biological significance of c-di-AMP in the opportunistic pathogen Enterococcus faecalis, we utilized high-throughout RNA Sequencing analysis to explore the impact of deletion of genes responsible for c-di-AMP synthesis (cdaA) and degradation (dhhP and gdpP).
2021-05-14 | GSE174381 | GEO
Project description:In this study, we showed for the first time that c-di-AMP is produced by C. difficile and controls the uptake of potassium, making it essential for growth. We found that c-di-AMP is involved in biofilm formation, cell wall homeostasis, osmotolerance as well as detergent and bile salt resistance in C. difficile. We identified BusR as a new regulator that binds c-di-AMP and represses the expression of the compatible solute transporter BusAA-AB. Interestingly, a busR mutant is highly resistant to a hyperosmotic or bile salt stress compared to the parental strain while a busAA mutant is more susceptible. A short exposure of C. difficile cells to bile salts resulted in a decrease of the c-di-AMP concentrations reinforcing the hypothesis that changes in membrane characteristics due to variations of the cellular turgor or membrane damages constitute a signal for the adjustment of the intracellular c-di-AMP concentration. In a colonization mouse model, a strain producing elevated c-di-AMP concentrations failed to persist in the gut in contrast to the parental strain. Thus, c-di-AMP is a signaling molecule with pleiotropic effects that controls osmolyte uptake to confer osmotolerance and bile salt resistance in C. difficile and that is important for colonization of the host.
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