Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Identification of the OsbR regulon in Chromobacterium violaceum

ABSTRACT: Here, we described a novel transcriptional regulator belonging to the MarR family that we named OsbR (oxidative stress response and biofilm formation regulator) in the opportunistic pathogen Chromobacterium violaceum. Transcriptome profiling by DNA microarray using strains with deletion or overexpression of osbR showed that OsbR exert a global regulatory role in C. violaceum, regulating genes involved in oxidative stress response, nitrate reduction, biofilm formation, and several metabolic pathways. EMSA assays showed that OsbR binds to the promoter regions of several OsbR-regulated genes and the in vitro DNA binding activity was inhibited by oxidants. We demonstrated that the overexpression of osbR caused activation of ohrA even in the presence of the repressor OhrR, which resulted in improved growth under organic hydroperoxide treatment. We showed that the proper regulation of the nar genes by OsbR ensures an optimal growth of C. violaceum under anaerobic conditions by tuning the reduction of nitrate to nitrite. Finally, the osbR overexpressing strain showed reduction in biofilm formation and this phenotype correlated with the OsbR-mediated repression of two gene clusters encoding putative adhesins.

ORGANISM(S): Chromobacterium violaceum Chromobacterium violaceum ATCC 12472

PROVIDER: GSE171860 | GEO | 2021/04/11

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

Identification of the EmrR regulon in Chromobacterium violaceum

Project description:Antibiotic resistance can arise by several mechanisms, including mutation in transcription factors that regulate drug efflux pumps. In this work, we identified EmrR as a MarR family transcription factor involved in antibiotic resistance in Chromobacterium violaceum, a Gram-negative bacterium that occurs in soil and water and can act as a human opportunistic pathogen. Antibiogram and minimum inhibitory concentration (MIC) assays showed that the ΔemrR mutant presented increased resistance to the antibiotic nalidixic acid in respect to the wild-type strain. The emrR gene is near to a putative operon emrCAB, which encode the efflux pump EmrCAB. DNA Microarray analysis showed that EmrR represses the emrCAB operon and some other putative transporters. Northern blot assays validated that EmrR represses the emrCAB operon and this repression can be released by salicylate, but not other compounds such as nalidixic acid or ethidium bromide. Electrophoretic mobility shift assays (EMSA) showed that EmrR binds directly to the promoter regions of emrR, emrCAB and other genes to exert negative regulation. Therefore, in response to compounds as salicylate, EmrR derepresses the operon emrCAB causing overexpression of the efflux pump EmrCAB and increased resistance to nalidixic acid in C. violaceum.

2018-11-01 | GSE112521 | GEO

Heterologous acyl-homoserine lactone synthase expression in Pseudomonas putida

Project description:Many bacteria harbor an incomplete quorum sensing system, wherein they possess LuxR homologues without the quorum sensing acyl-homoserine lactone (AHL) synthase, which is encoded by a luxI homolog. An artificial AHL-producing plasmid was constructed using a cviI gene encoding for C6-AHL (HHL) synthase from Chromobacterium violaceum and was introduced successfully into both wild-type and the ppoR (a luxR homolog) mutant. Our data provides evidence to suggest that the PpoR-HHL complex, but neither PpoR nor HHL alone, could attenuate growth, antibiotic resistance, and biofilm formation ability. In contrast, swimming motility, siderophore production, and indole degradation were enhanced by PpoR-HHL. The addition of exogenous indole increased biofilm formation and reduce swimming motility. Interestingly, indole proved ineffective in the presence of PpoR-HHL, thereby suggesting that the PpoR-HHL complex masks the effects of indole. Our data was supported by transcriptome analyses showing that the presence of the plasmid-encoded AHL synthase altered the expression of many genes on the chromosome in strain KT2440. Our results showed that heterologous luxI expression occurring via horizontal gene transfer can regulate a broad range of specific target genes, resulting in alterations of the phenotype and physiology of host cells.

2010-08-22 | GSE23632 | GEO

Chromobacterium violaceum

Project description:Cumene hydroperoxide stimulon and OhrR regulon in Chromobacterium violaceum

| PRJNA355004 | ENA

Cumene hydroperoxide stimulon and OhrR regulon in Chromobacterium violaceum

Project description:In this study, we used transcriptional profiling to define the adaptive response of C. violaceum to oxidative stress induced by cumene hydroperoxide (CHP) and to identify the OhrR regulon. DNA microarray and northern blot analysis revealed that in CHP-treated cells occur strong upregulation of genes involved in many pathways for stress protection, including antioxidant enzymes (catalase and peroxidases), thioredoxin, glutaredoxin and lipoyl-dependent reducing systems, DNA repair enzymes, heat shock response (σ32 regulon), iron limitation (Fur regulon) and nitrogen starvation. Genes encoding glyoxalases, glutathione S-transferases and oxygenases were also induced, suggesting further catabolism of the aromatic compound CHP. Pathways downregulated by CHP stress include electron transport chain, nucleotide biosynthesis and unsaturation of fatty acids. Further, we identified two upregulated genes (OhrA and a protein with GGDEF domain for c-di-GMP synthesis) and three downregulated genes (hemolysin, chitinase and collagenase) in the ohrR mutant. Using a mouse infection model, we demonstrate that the ohrR mutant, but not the ohrA mutant, is attenuated for virulence and showed a decreased bacterial burden in the liver. Therefore, we have defined the CHP stimulon and determined that C. violaceum uses the organic hydroperoxide sensor OhrR for regulate expression of genes required to antioxidant defense and to modulate virulence in its interaction with the host.

2017-05-01 | GSE90551 | GEO

The Campylobacter jejuni transcriptional regulator CosR plays a role in the oxidative and aerobic stress response and is important for bacterial survival in vivo

Project description:Campylobacter jejuni is the leading bacterial cause of human gastroenteritis worldwide. Despite stringent microaerobic growth requirements, C. jejuni is ubiquitous in the aerobic environment. C. jejuni must possess finely tuned regulatory systems to sense and adapt to external stimuli such as oxidative and aerobic (O2) stress. Re-annotation of the C. jejuni NCTC11168 genome sequence identified Cj1556 (originally annotated as a hypothetical protein) as a MarR family transcriptional regulator and further bioinformatic analysis indicated a role in regulating the oxidative stress response. A C. jejuni 11168H Cj1556 mutant exhibited increased sensitivity to oxidative and aerobic stress, decreased ability for intracellular survival in both Caco-2 human intestinal epithelial cells and J774A.1 mouse macrophages and a reduction in virulence in the Galleria mellonella infection model. Microarray analysis of gene expression changes in the Cj1556 mutant compared to the wild-type strain indicated negative autoregulation of Cj1556 expression and down-regulation of genes associated with oxidative and aerobic stress responses, such as katA, perR and hspR. cprS, which encodes a sensor kinase involved in the regulation of biofilm formation, was also up-regulated in the Cj1556 mutant and subsequent studies showed that the Cj1556 mutant had a reduced ability to form biofilms. Protein interaction studies confirmed the binding of recombinant Cj1556 to a region upstream of Cj1556. This study has identified a novel C. jejuni transcriptional regulator Cj1556 that is involved in oxidative and aerobic stress responses and is important for the survival of C. jejuni in the natural environment and in vivo. This newly identified regulator was designated CosR (Campylobacter oxidative stress Regulator). Data is also available from <ahref=""http://bugs.sgul.ac.uk/E-BUGS-119"" target=""_blank"">BuG@Sbase</a>

2012-01-23 | E-BUGS-119 | biostudies-arrayexpress

Reduction of alternative electron acceptors drives biofilm formation in Shewanella algae

Project description:Shewanella spp. possess a broad respiratory versatility, which contributes to the occupation of hypoxic/anoxic environmental or host-associated niches. Here we observed a strain-specific induction of biofilm formation in response to supplementation with the anaerobic electron acceptors dimethyl sulfoxide (DMSO) and nitrate in a panel of Shewanella algae isolates. The respiration-driven biofilm response is not observed in DMSO and nitrate reductase deletion mutants of the type strain S. algae CECT 5071, and can be restored upon complementation with the corresponding reductase operon(s) but not by an operon containing a catalytically inactive nitrate reductase. The distinct transcriptional changes, proportional to the effect of these compounds on biofilm formation, include cyclic di-GMP (c-di-GMP) turnover genes. In support, ectopic expression of the c-di-GMP phosphodiesterase YhjH of Salmonella Typhimurium but not its catalytically inactive variant decreased biofilm formation. The respiration-dependent biofilm response of S. algae may permit differential colonization of environmental or host niches.

2020-12-05 | GSE133627 | GEO

Role of the SaeRS two-component regulatory system in Staphylococcus epidermidis autolysis and biofilm formation

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

Transcriptome analysis of the shoots of Arabidopsis wild-type and mutants deficient in either or both activities of nitrate reductase and alternative oxidase

Project description:The conversion of nitrate to ammonium, known as nitrate reduction, consumes large amounts of reductants in plants. Previous studies have observed that mitochondrial alternative oxidase (AOX) is upregulated under conditions of limited nitrate reduction, such as low or no nitrate availability, or when ammonium serves as the sole nitrogen (N) source. Electron transfer from ubiquinone to AOX bypasses the proton-pumping complexes III and IV, thereby consuming reductants efficiently. Therefore, the upregulation of AOX under conditions of limited nitrate reduction may help dissipate excessive reductants and mitigate oxidative stress. However, firm evidence supporting this hypothesis is lacking due to the absence of experimental systems capable of directly analyzing the relationship between nitrate reduction and AOX. To address this gap, we developed a novel culturing system that allows for the manipulation of nitrate reduction and AOX activities separately, without inducing N starvation, ammonium toxicity, or disrupting the nitrate signal. Using this system, we investigated genome-wide gene expression with RNA-seq to gain insight into the relationship between AOX and nitrate reduction.

2024-04-23 | E-MTAB-14027 | biostudies-arrayexpress

Role of the SaeRS two-component regulatory system in Staphylococcus epidermidis autolysis and biofilm formation

2012-01-12 | GSE29309 | GEO

Chromobacterium violaceum

Project description:Chromobacterium violaceum Genome sequencing

| PRJNA413993 | ENA