The unusual mode of action of the polyketide glycoside antibiotic cervimycin C [I]
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ABSTRACT:
ORGANISM(S): Staphylococcus aureus
PROVIDER: GSE209674 | GEO | 2024/04/02
REPOSITORIES: GEO
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Project description:Cervimycins A-D are bis-glycosylated polyketide antibiotics produced by Streptomyces tendae HKI 0179 with bactericidal activity against Gram-positive bacteria. In this study, cervimycin C (CmC) treatment caused a spaghetti-like phenotype in Bacillus subtilis 168, with elongated curved cells, which stayed joined after cell division, and exhibited a chromosome segregation defect, resulting in ghost cells without DNA. Electron microscopy of cervimycin treated S. aureus (3 x MIC) revealed swollen cells, misshapen septa, cell wall thickening, and a rough cell wall surface. Incorporation tests in B. subtilis indicated an effect on DNA biosynthesis at high cervimycin concentrations. Indeed, artificial down-regulation of the DNA gyrase subunit B gene (gyrB) increased the activity of cervimycin in agar diffusion tests, and, in high concentrations (starting at 62.5 x MIC), the antibiotic inhibited S. aureus DNA gyrase supercoiling activity in vitro. To obtain a more global view on the mode of action of CmC, transcriptomics and proteomics of cervimycin treated versus untreated S. aureus cells were performed. Interestingly, 3 x MIC of cervimycin did not induce the SOS response, which would indicate disturbance of the DNA gyrase activity in vivo. Instead, cervimycin induced the expression of the CtsR/HrcA heat shock operon and the expression of autolysins, exhibiting similarity to the ribosome-targeting gentamicin. In summary, we identified the DNA gyrase as a target, but at low concentrations electron microscopy and omics data revealed a more complex mode of action of cervimycin, that comprised induction of the heat shock response, indicating protein stress in the cell. A synergistic effect was seen when sodium chloride (NaCl) was added during cervimycin MIC testing of S. aureus SG511. Thus, transcriptomics of S. aureus cells under osmotic stress (1 M NaCl) were performed. The stress response was compared to the cervimycin stress response to identify factors which might contribute to the synergistic antibacterial effect of the two molecules.
2024-04-02 | GSE250540 | GEO
Project description:WalKR is a two-component system that is essential for viability in Gram-positive bacteria that regulates the all-important autolysins. Here we show a T101M mutation in walR confers a defect in autolysis, a thickened cell wall and decreased sensitivity to antibiotics that target the lipid II cycle, a phenotype that is reminiscent of the clinical resistance form known as vancomycin intermediate-resistant Staphylococcus aureus. Importantly, this is accompanied by dramatic sensitization to tunicamycin. We demonstrate that this phenotype is due to partial collapse of a pathway consisting of autolysins, AtlA and Sle1, a transmembrane sugar permease, MurP, and GlcNAc recycling enzymes, MupG and MurQ. We suggest that this causes a shortage of substrate for MraY causing it to be hypersensitive to competitive inhibition by tunicamycin. This constitutes a new molecular model for antibiotic sensitivity in S. aureus and a promising new route for antibiotic discovery.
2022-08-25 | GSE211745 | GEO
Project description:The bacterial cell wall has been a celebrated target for antibiotics and holds real promise as a target for the discovery of new chemical matter to surmount pervasive multi-drug resistance among pathogenic bacteria. While the walls of Gram-negative bacteria are composed primarily of peptidoglycan, those of Gram-positives are more substantial and contain, in addition, large amounts of the polymer teichoic acid, covalently attached to peptidoglycan. Wall teichoic acids are a diverse group of phosphate-rich, extracellular polysaccharides that have been largely regarded as ancillary cell surface components. Recently, wall teichoic acid was shown to be essential to the proper rod-shaped cell morphology of the prototype Gram-positive bacterium Bacillus subtilis and an important virulence factor for the human pathogen Staphylococcus aureus. Thus wall teichoic acid synthesis is an intriguing target for the development of new cell wall-active antibiotics. Nevertheless, recent studies have shown that the dispensability of genes encoding teichoic acid biosynthetic enzymes in both B. subtilis and S. aureus is paradoxical and complex. Here, we report here on the discovery of a promoter (PywaC), which is sensitive to lesions in teichoic acid synthesis. Using this promoter we developed a luminescent, cell-based, reporter system to take a chemical-genetic approach to understanding the complexity of wall teichoic acid biogenesis using a large collection of antibiotics of well characterized biological activity. Our results reveal surprising interactions among undecaprenol, peptidoglycan and teichoic acid biosynthesis that help explain the complexity of teichoic acid gene dispensability. Furthermore, the new reporter assay represents an exciting avenue for the discovery of novel antibacterial molecules that impinge broadly on Gram-positive bacterial cell wall biogenesis. Keywords: comparison between depleted and repleted tagD mutant
2008-03-01 | GSE7373 | GEO
Project description:Resistance to antibiotics is an emerging problem and necessitates novel antibacterial therapies. Cervimycins A‒D are natural products of Streptomyces tendae HKI 0179 with promising activity against multidrug resistant staphylococci and vancomycin resistant enterococci. We studied the mode of action of cervimycin C and D by selection of cervimycin resistant (CmR) Staphylococcus aureus strains. Genome sequencing of CmR mutants revealed amino acid exchanges in the essential histidine kinase WalK, the Clp protease proteolytic subunit ClpP or the Clp ATPase ClpC, and the heat shock protein DnaK. Interestingly, all characterized cervimycin resistant mutants harbored a combination of mutations in walK and clpP or clpC. Mutations in the Clp system abolished ClpP or ClpC activity, and the deletion of clpP rendered S. aureus but not B. subtilis cervimycin resistant. The essential gene walK was the second mutational hotspot in the cervimycin resistant S. aureus mutants, which decreased WalK activity in vitro and generated a vancomycin intermediately resistant phenotype, with a thickened cell wall, a slower growth rate, and reduced cell lysis. Transcriptomic and proteomic analysis revealed massive alterations in the CmR strains , with major alterations in the heat shock regulon, the metal ion homeostasis and the carbohydrate metabolism. Taken together, compensatory mutations in cervimycin resistant mutants induced a VISA phenotype in S. aureus, suggesting cell wall metabolism or the ClpCP proteolytic system as primary target of the polyketide antibiotic
2022-09-08 | GSE206309 | GEO
Project description:Daptomycin is a lipopeptide antibiotic that has recently been approved for treatment of Gram-positive bacterial infections. The mode of action of daptomycin is not yet entirely clear. To further understand the mechanism transcriptomic analysis of changes in gene expression in daptomycin-treated Staphylococcus aureus was carried out. The expression profile indicated that cell wall stress stimulon member genes (B. J. Wilkinson, A. Muthaiyan, and R. K. Jayaswal. 2005. Curr. Med. Chem. Anti-Infective Agents 4: 259-276) were significantly induced by daptomycin, and by the cell wall-active antibiotics vancomycin and oxacillin. Comparison of the daptomycin response of a two-component cell wall stress stimulon regulator VraSR mutant, S. aureus KVR, to its parent N315 showed diminished expression of the cell wall stress stimulon in the mutant. Daptomycin has been proposed to cause membrane depolarization, and the transcriptional responses to carbonyl cyanide m-chlorophenylhydrazone (CCCP) and nisin were determined. Transcriptional profiles of the responses to these antimicrobial agents showed significantly different patterns compared to those of the cell wall-active antibiotics, including little or no induction of the cell wall stress stimulon. However, there were a significant number of genes induced by both CCCP and daptomycin that were not induced by oxacillin or vancomycin, such that the daptomycin transcriptome was probably reflecting a membrane depolarizing activity of this antimicrobial also. The results indicate that inhibition of peptidoglycan biosynthesis, either directly or indirectly, and membrane depolarization are parts of the mode of action of daptomycin. Keywords: mode of action, transcriptional profiling
2007-12-25 | GSE9494 | GEO
Project description:Bacterial cell envelope is the first and the major line of defense against threats from the environment. Because of its crucial roles in bacterial cell life, cell envelope is a prime target for numerous antibiotics. In this study, by treating Gram-positive model strain Bacillus subtilis with numbers of cell wall targeted antibiotics, we aimed to obtain a global comprehensive transcriptional profile of cell envelope stress response in B. subtilis via transcriptomic study using high-throughput RNA sequencing approach. This knowledge will then be subject to a series of comparative genomics analyses to get detailed information of the distribution and conservation of cell envelope stress-sensing regulatory systems in B. subtilis.
2023-10-28 | GSE160345 | GEO
Project description:For Staphylococcus aureus it was shown previously that aminocoumarinecoumarin antibiotics such as novobiocin lead to immediate down-regulation of recA expression and thereby inhibition of the SOS response, the mutation frequency and the recombination capacity. Aminocoumarinecoumarin function by inhibition of the ATPase activity of the gyrase subunit B. Here we analysed the global impact of the DNA relaxing agent novobiocin on gene expression in S. aureus. By use of a novobiocin resistant mutant, it became evident that the change in recA expression is due to gyrase inhibition. Microarray analysis and Northern blot hybridization revealed that the expression of a distinct set of genes is increased (e.g. recF-gyrB-gyrA, rib operon and ure operon M-bM-^@M-&)), or decreased (e.g. arlRS, recA, lukA, hlgC, fnbA) by novobiocin. The two-component ArlRS system was previously found to decrease the supercoiling level in S. aureus. Thus, down-regulation of arlRS might in part compensate for the relaxing effect of novobiocin. Novobiocin resulted in down-regulation of several of arlRS repressed target genes in an arl mutant. Global analysis and gene mapping of supercoiling sensitive genes did not give indications that they are clustered in the genome. Promoter fusion assays confirmed that responsiveness of a given gene is intrinsic to the promoter region but independent of the chromosomal location. The results indicate that molecular property of the spacers of a given promoter dictatesa given promoter rather than chromosomal topology dictates the responsiveness towards changes in supercoiling rather than chromosomal topology. We analyzed S. aureus global gene expression changes to the treatment of novobiocin
2014-09-08 | E-GEOD-50157 | biostudies-arrayexpress
Project description:The lantibiotic mersacidin is an antimicrobial peptide of 20 amino acids that is ribosomally produced by Bacillus sp. strain HIL Y-85,54728. Mersacidin acts by complexing the sugar phosphate head group of the peptidoglycan precursor lipid II, thereby inhibiting the transglycosylation reaction of peptidoglycan biosynthesis. Here, we studied the transcriptomic response of S. aureus to subinhibitory concentrations of mersacidin using microarray and qRT-PCR techniques. The transcriptomics revealed an extensive induction of the cell wall stress response of S. aureus, which is partly controlled by the two-component regulatory system VraSR. In contrast to other cell wall-active antibiotics such as vancomycin, 0.2 x MIC of mersacidin was sufficient for induction. Interestingly, the cell wall stress response was equally induced in vancomycin intermediate resistant S. aureus (VISA) as well as in a highly susceptible strain. Furthermore, the efficiency of mersacidin was not affected by an increased cell wall thickness, which is part of the VISA-type resistance mechanism. Since the transcription of the VraDE ABC transporter genes was induced up to 1700-fold in our experiments, we analyzed the role of VraDE in the response of S. aureus to mersacidin. Unexpectedly, the deletion of the vraE gene did not result in an increased susceptibility to mersacidin compared to the wild type strain. In conclusion, mersacidin appears to be a strong inducer of the cell wall stress response of S. aureus at very low concentrations, which reflects its general mode of action as a cell wall-active peptide as well as its use of a unique target site on lipid II. Keywords: antibiotic induced response
2008-10-23 | GSE9261 | GEO
Project description:Various bis-benzimidazole derivatives have been reported to possess activity against Gram-positive pathogens. No mechanism of action has been elucidated to fully account for the antibacterial activity of this class of compounds. A group of symmetric bis-benzimidazoles (BBZ) designed as anticancer agents have previously been shown to possess moderate antiproliferative activity. We sought to assess the antibacterial activity and mechanism of action of BBZ compounds against Staphylococcus aureus. Antibacterial activities were assessed by determination of minimal inhibitory concentrations (MICs), time-kill curves, and scanning electron microscopy. Transcriptional responses to BBZ treatment were determined using whole genome microarrays. Activities against bacterial type II topoisomerases were investigated using in vitro supercoiling, decatenation, DNA binding, and DNA cleavage inhibition assays. MICs for EMRSA-16 were between 0.03 and 0.5 μg/mL. The compounds showed concentration-dependent bactericidal activity and induced cell swelling and lysis. Transcriptional responses to BBZ were consistent with topoisomerase inhibition and DNA damage. A subset of BBZ compounds inhibited S. aureus DNA gyrase supercoiling activity with IC50 values in the range of 5−10 μM. This inhibition was subsequently shown to operate through both inhibition of binding of DNA gyrase to DNA and accumulation of single-stranded DNA breaks. We conclude that BBZ compounds are potent antistaphylococcal agents and operate at least in part through DNA gyrase inhibition, leading to the accumulation of single-stranded DNA breaks, and by preventing the binding of gyrase to DNA. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-106]
2012-10-14 | E-BUGS-106 | biostudies-arrayexpress
Project description:Understanding how pathogens respond to antimicrobial peptides, and how this compares to currently available antibiotics, is crucial to optimizing antibiotic therapy. Staphylococcus aureus has several known resistance mechanisms against human cationic antimicrobial peptides (CAMPs). We aim to determine how S. aureus responds to sheep and frog CAMPs, and whether this response is associated with resistance. Gene expression changes in Staphylococcus aureus Newman cells exposed to linear CAMPs were analyzed by DNA microarray. Three antimicrobial peptides were used in the analysis, two of them are derived from frog, temporin L and dermaseptin K4-S4(1-16), one is from sheep, ovispirin-1. The peptides induced the VraSR cell-wall regulon and several other genes which are also upregulated in cells treated with vancomycin and other cell wall-active antibiotics. In addition to this similarity, three genes/operons were particularly strongly induced by the peptides: vraDE, SA0205 and SAS016, encoding an ABC transporter, a putative membrane-bound lysostaphin-like peptidase and a small functionally unknown protein, respectively. Ovispirin-1 and dermaseptin K4-S4(1-16), which disrupt lipid bilayers by the carpet mechanism, were strong inducers of the vraDE operon. We show that high level induction by ovispirin-1 was dependent on the amide modification of the peptide C-terminus. This suggests that the amide group has a crucial role in the activation of the Aps sensory system, the regulator of vraDE. In contrast, temporin L, which disrupts lipid bilayers by forming pores, was clearly a weaker inducer of vraDE despite the C-terminal amide modification. Sensitivity testing with CAMPs and other antimicrobials suggested that VraDE is a transporter dedicated to resist bacitracin. We also showed that SA0205 belongs to the VraSR regulon. Furthermore, VraSR was shown to be important for resistance against a wide range of cell wall-active antibiotics and other antimicrobial agents including the amide-modified ovispirin-1, bacitracin, teicoplanin, cefotaxime and 10 other β-lactam antibiotics, chlorpromazine, thioridazine and EGTA. The effects of the three different antimicrobial peptides on gene expression of S. aureus Newman were studied by using whole genome oligo-DNA microarrays. Bacteria were grown in BHI medium to the early exponential phase (OD600=0.6) and antimicrobial peptides were added at sublethal concentrations. Samples were taken for RNA isolations after treating the cultures with the peptides for 10 minutes. Control cultures without peptide additions were treated similarly and in parallel.
2010-03-01 | E-GEOD-15800 | biostudies-arrayexpress