RNA-Seq for identification of differntially expressed genes by VxrB(D78E) overexpression
Ontology highlight
ABSTRACT:
ORGANISM(S): Vibrio cholerae O1 biovar El Tor str. N16961
PROVIDER: GSE135010 | GEO | 2019/07/30
REPOSITORIES: GEO
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Project description:Bactericidal antibiotics are powerful drugs because they not only inhibit essential bacterial functions, but convert them into toxic processes. Many bacteria are remarkably tolerant against antibiotics, due to inducible damage repair responses. How these responses promote whole population tolerance in important human pathogens is poorly understood. The two-component system VxrAB of the diarrheal pathogen Vibrio cholerae, a model system for tolerance against cell wall damaging (e.g., beta-lactam) antibiotics, is required for high-level beta-lactam tolerance. Here, we report the mechanism of VxrAB-mediated survival. We find that -lactam antibiotics inappropriately induce the Fur-regulated iron starvation response, causing an increase in intracellular free iron and colateral oxidative damage. VxrAB reduces antibiotic-induced toxic influx of Fe by downregulating iron importers and induces cell wall synthesis functions to counteract cell wall damage. Our results highlight the complex responses elicited by antibiotics and suggest that the ability to counteract diverse stresses promotes high-level antibiotic tolerance.
2019-07-30 | GSE135009 | GEO
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:Gram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by Gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth new peptidoglcyan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how Gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identify Escherichia coli stress responses activated following inhibition of specific PBPs by the β-lactam antibiotics mecillinam and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all of the PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance of E. coli to β-lactam antibiotics. We used microarrays to identify changes in gene expression resulting from treatment of Escherichia coli with the β-lactam antibiotics cefsulodin, mecillinam, or the combination. Experiment Overall Design: E. coli was treated with two b-lactam antibiotics, cefsulodin and mecillinam, alone at the minimum inhibitory concentration to identify the expression changes in response to antibiotic-induced peptidoglycan stress. E. coli was grown to an OD of 0.2 at which time cefsulodin or mecillinam was added. Samples of the bacteria were collected at 5 and 10 minutes after treatment with cefsulodin and 60 minutes after treatment with mecillinam. Untreated cells were also collected at the same time points as controls. Three biological replicates were collected for all time points and samples, however, only one of the 5 minute untreated samples was hybridized to the arrays. In addition, a single sample from cells treated with the combination of cefsulodin and mecillinam was hybridized to allow for comparison with samples hybridized to Affymetrix antisense genechips.
2008-10-20 | E-GEOD-10159 | biostudies-arrayexpress
Project description:Gram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by Gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth new peptidoglcyan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how Gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identify Escherichia coli stress responses activated following inhibition of specific PBPs by the β-lactam antibiotics mecillinam and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all of the PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance of E. coli to β-lactam antibiotics. We used microarrays to identify changes in gene expression resulting from treatment of Escherichia coli with the β-lactam antibiotics cefsulodin, mecillinam, or the combination. Experiment Overall Design: E. coli was treated with two b-lactam antibiotics, cefsulodin and mecillinam, alone and in combination to identify the expression changes in response to antibiotic-induced peptidoglycan stress. E. coli was grown to an OD of 0.2 at which time low concentrations of cefsulodin and mecillinam were added individually or in combination. Samples of the bacteria were collected 5 minutes before treatment as well as 5, 20 and 40 minutes after treatment. Untreated cells were also collected at the same time points to serve as controls. At least three biological replicates were collected for all time points and samples, however, only the replicates for the 40 minute time points and the combination time points were hybridized to the arrays as no changes observed for the individual treatments, even at the 40 minute time point.
2008-10-25 | E-GEOD-10158 | biostudies-arrayexpress
Project description:Evolution of antibiotic resistance in microbes is frequently achieved by acquisition of spontaneous mutations during antimicrobial therapy. Here we demonstrate that inactivation of a central regulator of iron homeostasis (fur) facilitates laboratory evolution of ciprofloxacin resistance in Escherichia coli. To decipher the underlying molecular mechanisms, we first performed a global transcriptome analysis and demonstrated a substantial reorganization of the Fur regulon in response to antibiotic treatment. We hypothesized that the impact of Fur on evolvability under antibiotic pressure is due to the elevated intracellular concentration of free iron and the consequent enhancement of oxidative damage-induced mutagenesis. In agreement with expectations, over-expression of iron storage proteins, inhibition of iron transport, or anaerobic conditions drastically suppressed the evolution of resistance, while inhibition of the SOS response-mediated mutagenesis had no such effect in fur deficient population. In sum, our work revealed the central role of iron metabolism in de novo evolution of antibiotic resistance, a pattern that could influence the development of novel antimicrobial strategies. We used microarrays to identify genotype specific transcriptional changes under severe DNA damaging conditions (antibiotic ciprofloxacin). We treated Escherichia coli cells with a highly toxic level of ciprofloxacin (gyrase inhibitor) for RNA extraction and hybridization on Affymetrix microarrays. We planned to find genotype specific transcriptional responses using WT control (BW25113) and fur-knockout mutant (selected from the KEIO collection) strains during antibiotic treatments. For each treatment type we used two biological replicates.
2014-09-11 | E-GEOD-55662 | biostudies-arrayexpress
Project description:Tan2012 - Antibiotic Treatment, Inoculum Effect
The efficacy of many antibiotics decreases with increasing bacterial density, a phenomenon called the ‘inoculum effect’ (IE). This study reveals that, for ribosome-targeting antibiotics, IE is due to bistable inhibition of bacterial growth, which reduces the efficacy of certain treatment frequencies.
This model is described in the article:
The inoculum effect and band-pass bacterial response to periodic antibiotic treatment.
Tan C, Phillip Smith R, Srimani JK, Riccione KA, Prasada S, Kuehn M, You L.
Mol Syst Biol. 2012 Oct 9; 8:617
Abstract:
The inoculum effect (IE) refers to the decreasing efficacy of an antibiotic with increasing bacterial density. It represents a unique strategy of antibiotic tolerance and it can complicate design of effective antibiotic treatment of bacterial infections. To gain insight into this phenomenon, we have analyzed responses of a lab strain of Escherichia coli to antibiotics that target the ribosome. We show that the IE can be explained by bistable inhibition of bacterial growth. A critical requirement for this bistability is sufficiently fast degradation of ribosomes, which can result from antibiotic-induced heat-shock response. Furthermore, antibiotics that elicit the IE can lead to 'band-pass' response of bacterial growth to periodic antibiotic treatment: the treatment efficacy drastically diminishes at intermediate frequencies of treatment. Our proposed mechanism for the IE may be generally applicable to other bacterial species treated with antibiotics targeting the ribosomes.
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2024-09-02 | BIOMD0000000425 | BioModels
Project description:Staphylococcus aureus is responsible for a substantial number of invasive infections globally each year. These infections are problematic because they are frequently recalcitrant to antibiotic treatment. Antibiotic tolerance, the ability of bacteria to persist despite normally lethal doses of antibiotics, contributes to antibiotic treatment failure in S. aureus infections. To understand how antibiotic tolerance is induced, S. aureus biofilms exposed to multiple anti-staphylococcal antibiotics were examined using both quantitative proteomics and transposon sequencing. These screens indicated that arginine metabolism is involved in antibiotic tolerance within a biofilm and led to the hypothesis that depletion of arginine within S. aureus communities can induce antibiotic tolerance. Consistent with this hypothesis, inactivation of argH, the final gene in the arginine synthesis pathway, induces antibiotic tolerance. Arginine restriction was found to induce antibiotic tolerance via inhibition of protein synthesis. In a mouse skin infection model, an argH mutant has enhanced ability to survive antibiotic treatment with vancomycin, highlighting the relationship between arginine metabolism and antibiotic tolerance during S. aureus infection. Uncovering this link between arginine metabolism and antibiotic tolerance has the potential to open new therapeutic avenues targeting previously recalcitrant S. aureus infections.
2024-07-10 | GSE267626 | GEO
Project description:Non-typeable Haemophilus influenzae (NTHi) is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth) stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10M-BM-5g/mL) of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended. 12 samples
2014-06-04 | E-GEOD-58213 | biostudies-arrayexpress
Project description:Mycobacterium abscessus (Mab) causes serious infections that often require over 18 months of antibiotic combination therapy. With β lactam antibiotics being safe, double β-lactam and β-lactam/β-lactamase inhibitor combinations are of interest for improving treatment of Mab infections and minimizing toxicity. However, a mechanistic approach for building these combinations is lacking since little is known about which penicillin-binding protein (PBP) target receptors are inactivated by different β-lactams in Mab. This project aimed to identify PBPs in Mab and study the binding affinities of each of these PBPs with β-lactam antibiotics. These first PBP occupancy patterns in Mab provide a mechanistic foundation for selecting and optimizing safe and effective combination therapies with β-lactams.
2020-11-24 | PXD022644 | Pride
Project description:According to our study, Chrysanthemum lavandulifolum extract showed excellent antibiotic effects on Escherichia coli O157:H7. A notable point is that the antibiotic efficacy of the herb extract is on the all three proven targets for main antibiotic drugs that are bacterial cell wall biosynthesis, bacterial protein synthesis and bacterial DNA replication and repair. This multi-target efficacy of the herbal antibiotics may be used as more effective and safe drugs that substitute existing antibiotics.
2010-12-14 | GSE26017 | GEO