Impact of the (p)ppGpp synthesis and maintenance of GTP homeostasis during stationary phase starvation on the transcriptome
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ABSTRACT:
PROVIDER: PRJNA1071511 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR27798735.fastq.gz | Fastqsanger.gz | |||
| SRR27798736.fastq.gz | Fastqsanger.gz | |||
| SRR27798737.fastq.gz | Fastqsanger.gz | |||
| SRR27798738.fastq.gz | Fastqsanger.gz | |||
| SRR27798739.fastq.gz | Fastqsanger.gz |
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Project description:This work investigates the molecular mechanisms that determine the requirement of (p)ppGpp-mediated GTP homeostasis for viability during prolonged nutritional stress. Initially, we observed that the absence of (p)ppGpp in S. aureus resulted in reduced culturability and elevated levels of guanosine nucleotides (GMP, GDP, and GTP) when cells experienced prolonged starvation during stationary phase. Analysis of metabolic activity and cell membrane function revealed, that (p)ppGpp-deficiency does not immediately lead to cell death but rather to a VBNC state where cell become division-incompetent and display reduced metabolic activity. The cell membrane stayed intact, however (p)ppGpp-deficient cells displayed reduced membrane potential and increased membrane fluidity. Since missing translation inhibition and elevated oxidative stress levels could not be identified as the cause for the VBNC state of the (p)ppGpp-deficient cells, we conducted transcriptomic analysis on S. aureus wildtype and a (p)ppGpp0 mutant, as well as isogenic guaBA-deficient strains, to gain a more thorough understanding of the genetic basis through which (p)ppGpp maintains cell homeostasis during nutritional stress in the stationary phase and the importance of cellular GTP homeostasis to ensure viability. RNAseq analysis revealed that the TCA cycle and electron transport chain, particularly complex IV/the terminal oxidase qoxABCD, were strongly downregulated in the (p)ppGpp-deficient starved cells. By mutating the initiation nucleotide (TSS +1) of the qoxABCD operon, we were able to increase qoxA expression and membrane potential in a (p)ppGpp0 strain during stationary phase starvation. This resulted in increased culturability during prolonged nutrient starvation, demonstrating the necessity of PMF maintenance. Furthermore , we could show that the decreased membrane potential in starved (p)ppGpp-deficient cells contributes to decreased antibiotic tolerance towards oxacillin and ciprofloxacin. In summary, our data suggests, that (p)ppGpp-dependent regulation of cellular GTP homeostasis during nutritional stress is crucial for maintenance of culturability and antibiotic tolerance.
2025-02-21 | GSE254567 | GEO
Project description:Cells constantly adjust their metabolism in response to environmental conditions, yet major mechanisms underlying survival remain poorly understood. We discover a post-transcriptional mechanism that integrates starvation response with GTP homeostasis to allow survival, enacted by the nucleotide (p)ppGpp, a key player in bacterial stress response and persistence. We reveal that (p)ppGpp activates global metabolic changes upon starvation, allowing survival entirely by regulating GTP. Combining metabolomics with biochemical demonstrations, we find that (p)ppGpp directly inhibits the activities of multiple GTP biosynthesis enzymes. This inhibition results in robust and rapid GTP regulation in Bacillus subtilis, which we demonstrate is essential to maintaining GTP levels within a range that supports viability even in the absence of starvation. Correspondingly, without (p)ppGpp, gross GTP dysregulation occurs, revealing a vital housekeeping function of (p)ppGpp; in fact, loss of (p)ppGpp results in death from rising GTP, a severe and previously unknown consequence of GTP dysfunction.
2012-11-01 | GSE39758 | GEO
Project description:Cells constantly adjust their metabolism in response to environmental conditions, yet major mechanisms underlying survival remain poorly understood. We discover a post-transcriptional mechanism that integrates starvation response with GTP homeostasis to allow survival, enacted by the nucleotide (p)ppGpp, a key player in bacterial stress response and persistence. We reveal that (p)ppGpp activates global metabolic changes upon starvation, allowing survival entirely by regulating GTP. Combining metabolomics with biochemical demonstrations, we find that (p)ppGpp directly inhibits the activities of multiple GTP biosynthesis enzymes. This inhibition results in robust and rapid GTP regulation in Bacillus subtilis, which we demonstrate is essential to maintaining GTP levels within a range that supports viability even in the absence of starvation. Correspondingly, without (p)ppGpp, gross GTP dysregulation occurs, revealing a vital housekeeping function of (p)ppGpp; in fact, loss of (p)ppGpp results in death from rising GTP, a severe and previously unknown consequence of GTP dysfunction. Four-condition experiment: wt, wt+RHX, (p)ppGpp0, (p)ppGpp0+RHX. Biological replicates: 3 for each sample. Reference: a mixture of wt RNA from different growth phases and wt backgrounds.
2012-11-01 | E-GEOD-39758 | biostudies-arrayexpress
Project description:Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays
2015-08-08 | GSE70092 | GEO
Project description:Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays relA mutant strain and its parents strain SC-19 were cultured in both glucose-abundant CDM (CDM containing 1% glucose) and glucose-deficient CDM (CDM containing 2% glucose) respectively. The bacteriain in exponential phase were collected for microarray analysis. Three independent experiments were performed.
2015-08-08 | E-GEOD-70092 | biostudies-arrayexpress
Project description:The nucleotide messenger (p)ppGpp allows bacteria to adapt to fluctuating environments by reprogramming the transcriptome. Despite its well-recognized role in gene regulation, (p)ppGpp is only known to directly affect transcription in Proteobacteria by binding to the RNA polymerase. Here we reveal a different mechanism of gene regulation by (p)ppGpp in Firmicutes from soil bacteria to pathogens: (p)ppGpp directly binds to the transcription factor PurR to downregulate purine biosynthesis. We identified PurR as a receptor of (p)ppGpp in Bacillus anthracis and revealed that (p)ppGpp strongly enhances PurR binding to its regulon in the Bacillus subtilis genome. A co-structure reveals that (p)ppGpp binds to a PurR pocket reminiscent of the active site of PRT enzymes that has been repurposed to serve a purely regulatory role, where the effectors (p)ppGpp and PRPP compete to allosterically control transcription. PRPP inhibits PurR DNA binding to induce transcription of purine synthesis genes, whereas (p)ppGpp antagonizes PRPP to enhance PurR DNA binding and repress transcription. A (p)ppGpp-refractory purR mutant fails to downregulate purine synthesis genes upon starvation. Our work establishes the precedent of (p)ppGpp as a classical effector of transcription repressors and reveals the key function of (p)ppGpp in regulating nucleotide synthesis through gene regulation, from the human intestinal tract to host-pathogen interfaces.
2021-12-10 | GSE185164 | GEO
Project description:Bacteria synthesize guanosine tetra- and penta phosphate (commonly referred to as (p)ppGpp) in response to environmental stresses. (p)ppGpp reprograms cell physiology and is essential for stress survival, virulence and antibiotic tolerance. Proteins of the RSH superfamily (RelA/SpoT Homologues) are ubiquitously distributed and hydrolyze or synthesize (p)ppGpp. Structural studies have suggested that the shift between hydrolysis and synthesis is governed by conformational antagonism between the two active sites in RSHs. RelA proteins of γ-proteobacteria exclusively synthesize (p)ppGpp and encode an inactive pseudo-hydrolase domain. Escherichia coli RelA synthesizes (p)ppGpp in response to amino acid starvation with cognate uncharged tRNA at the ribosomal A-site, however, mechanistic details to the regulation of the enzymatic activity on the ribosome remain elusive. Here, we show a novel role of the enzymatically inactive hydrolase domain in modulating the activity of the synthetase domain of RelA. Using random mutagenesis screening and functional studies, we identify a loop region (residues 114-130) in the hydrolase domain, which controls the synthetase activity. We show that a synthetase-inactive loop mutant of RelA is not affected for tRNA binding, but binds the ribosome less efficiently than wildtype RelA. Our data provide strong evidence to support the model that the hydrolase domain acts as a molecular switch to regulate the synthetase activity.
2021-03-31 | GSE150416 | GEO
Project description:Acinetobacter baumannii is a major cause of nosocomial infections which can survive in different hospital environments and its multidrug-resistant capacity is major concern now-a-days. ppGpp dependent stringent response mediates reprogramming of gene expression with diverse function in many bacteria. A baumannii A1S_0579 gene is responsible for ppGpp production. Transcriptome analysis of early stationary phase cultures represents several differentially expressed genes in ppGpp deficient strain (∆A1S_0579). We found that the expression of csu operon, which is important in pili biosynthesis for early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings showed that ppGpp signaling plays critical role in biofilm formation, surface motility, adherence and virulence of A baumannii. This study is the first demonstration of the association between ppGpp and pathogenicity of A. baumannii.
2021-05-01 | GSE173627 | GEO
Project description:Transcriptional profiling of Salmonella Typhimurium SL1344 parental starin and isogenic ∆relA, ∆spoT ppGpp null strain grown in LB medium with RNA samples talken at AD600=1.0 (mid log, ML), 2.3 (early stationary phase, ESP), 3.0 (mid stationary phase MSP) and 3.6 (Late stationary phase (LSP)
2013-07-03 | GSE48478 | GEO
Project description:The (p)ppGpp-dependent stress response is required for pathogenic bacteria to survive both outside and inside the host but the mechanisms behind this survival are mostly unknown. In this study, we characterize the (p)ppGpp metabolism in the opportunistic pathogen multi-drug-resistant Acinetobacter baumannii. We show that two stressful conditions potentially encountered during infection – iron starvation and polymyxin exposure – induce (p)ppGpp production. The absence of (p)ppGpp led to multiple consequences on the physiology of A. baumannii, including an increase of surface motility, a decrease in catalase activity, a poor survival upon nutrient starvation, a rapid killing during desiccation and a strong attenuation in a Galleria mellonella model of infection. Using a motility suppressor screen, we isolated multiple independent stringent mutations in rpoB and rpoC that suppress the (p)ppGpp-dependent phenotypes. By combining the suppressor screen with deep sequencing, we isolated dozens of additional mutants, expanding the list of putative stringent RNAP mutations described so far. Furthermore, our transcriptomic data reveal that (p)ppGpp deeply impacts the transcriptional landscape of A. baumannii on solid surface to induce many stress-related genes, including catalase and hydrophilins critical for tolerance to desiccation. This work highlights the functional interplay between (p)ppGpp and RNAP in the successful survival of A. baumannii in the environment but also during infection.
2025-12-10 | GSE302438 | GEO