DksA acts as a transcriptional switch in stress and virulence in Acinetobacter baumannii
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ABSTRACT:
PROVIDER: PRJNA715173 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR13989021_1.fastq.gz | Fastqsanger.gz | |||
| SRR13989021_2.fastq.gz | Fastqsanger.gz | |||
| SRR13989022_1.fastq.gz | Fastqsanger.gz | |||
| SRR13989022_2.fastq.gz | Fastqsanger.gz | |||
| SRR13989023_1.fastq.gz | Fastqsanger.gz |
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Project description:Ability to redirect limiting cellular resources accurately is key to bacteria for surviving in harsh environments that they often encounter during their lifetime. DksA, a transcriptional initiating factor, plays critical roles in regulating stress responses and antibiotic tolerance. Acinetobacter baumannii has become a major healthcare threat and responsible for both nosocomial and community acquired deadly infections worldwide. Yet, little is known about the role of DksA in A. baumannii. Here we describe a highly pleiotropic nature of DksA that it helps redirect the key metabolic pathways associated with the respiration, energy production, protein biosynthesis. Inhibition of ribosomal RNAs, ATP production by DksA is detrimental to bacteria under bacteriostatic stresses such as copper and trimethoprim. By contrast, it is required for survival in stresses that generate reactive-oxygen species such as zinc and gentamycin. Bacteria lacking DksA exhibit increase sensitivity to human serum, promote biofilm formation and capsule production. Not only does DksA show diverse phenotypes in vitro, but it also impacted on virulence in a niche specific manner during in vivo Galleria mellonella and murine infections. Our data collectively provides the detailed insight into the role of DksA in stress protection and virulence in A. baumannii and layout a roadmap for similar findings in other clinically important pathogens.
2022-09-13 | GSE169081 | GEO
Project description:Phenotypic heterogeneity is an important mechanism to regulate bacterial virulence, where a single regulatory switch is typically activated to generate virulent and avirulent subpopulations. The opportunistic pathogen Acinetobacter baumannii can transition at high-frequency between virulent (VIR-O) and avirulent (AV-T) subpopulations, distinguished by cells that form opaque or translucent colonies. We demonstrate that expression of twelve TetR-type transcriptional regulators (TTTRs) can drive cells from the VIR-O subpopulation to the AV-T state. Remarkably, in a subpopulation of VIR-O cells, four of these TTTRs were stochastically activated in different combinations to drive cells to the AV-T state, with each resulting AV-T subvariant exhibiting unique phenotypic differences. Due to their functional redundancy, a quadruple mutant with all four of these TTTRs inactivated was required to see a loss of VIR-O to AV-T switching. Further, we demonstrate a small RNA, SrvS, acts as a “rheostat”, where the levels of SrvS expression influences both the VIR-O to AV-T switching frequency and which TTTR is activated when VIR-O cells switch to AV-T. In summary, this work has revealed a new paradigm for phenotypic switching in bacteria, where an unprecedented number of related transcriptional regulators are activated in different combinations to control virulence and generate unique AV-T subvariants with distinct phenotypic properties.
2022-04-22 | GSE201049 | GEO
Project description:DksA is well-known for its regulatory role in the transcription of ribosomal RNA and genes involved in amino acid synthesis in many bacteria. DksA is also reported to control expression of virulence genes in pathogenic bacteria. Here, we elucidated the roles of the DksA-like protein (CJJ81176_0160, Cj0125c) in the pathogenesis of Campylobacter jejuni. Like in other bacteria, transcription of stable RNA was repressed by DksA under stressful conditions in C. jejuni. Transcriptomic and proteomic analyses of C. jejuni 81-176 and its isogenic dksA mutant showed differential expression of many genes involved in iron-related metabolism, flagellar synthesis and amino acid metabolism. Also the dksA mutant of C. jejuni demonstrated a decreased ability to invade into intestinal cells and to induce release of interleukin-8 from intestinal cells. These results suggest the DksA-like protein plays an important regulatory role in the physiology and virulence of C. jejuni. Keywords: dksA mutation of Campylobacter jejuni
2008-05-06 | GSE9866 | GEO
Project description:DksA is well-known for its regulatory role in the transcription of ribosomal RNA and genes involved in amino acid synthesis in many bacteria. DksA is also reported to control expression of virulence genes in pathogenic bacteria. Here, we elucidated the roles of the DksA-like protein (CJJ81176_0160, Cj0125c) in the pathogenesis of Campylobacter jejuni. Like in other bacteria, transcription of stable RNA was repressed by DksA under stressful conditions in C. jejuni. Transcriptomic and proteomic analyses of C. jejuni 81-176 and its isogenic dksA mutant showed differential expression of many genes involved in iron-related metabolism, flagellar synthesis and amino acid metabolism. Also the dksA mutant of C. jejuni demonstrated a decreased ability to invade into intestinal cells and to induce release of interleukin-8 from intestinal cells. These results suggest the DksA-like protein plays an important regulatory role in the physiology and virulence of C. jejuni. Keywords: dksA mutation of Campylobacter jejuni The design utilized a commercially available two color microarray slide for the enture transcriptome of Campylobacter jejuni. Six hybridizations were performed each with independently extracted samples of either C. jejuni wildtype of C. jejuni dksA mutant cDNA samples. A dye swap was utilized to help minimize dye dependent bias. Thus there were six biological replicates of each sample.
2008-05-05 | E-GEOD-9866 | biostudies-arrayexpress
Project description:In bacteria, translation-transcription coupling inhibits RNA polymerase (RNAP) stalling. We present evidence suggesting that, upon amino acid starvation, inactive ribosomes promote rather than inhibit RNAP stalling. We developed an algorithm to evaluate genome-wide polymerase progression independently of local noise, and used it to reveal that the transcription factor DksA inhibits promoter-proximal pausing and increases RNAP elongation when uncoupled from translation by depletion of charged tRNAs. DksA has minimal effect on RNAP elongation in vitro and on untranslated RNAs in vivo. In these cases, transcripts can form RNA structures that prevent backtracking. Thus, the effect of DksA on transcript elongation may occur primarily upon ribosome slowing/stalling or at promoter-proximal locations that limit the potential for RNA structure. We propose that inactive ribosomes prevent formation of backtrackblocking mRNA structures and that, in this circumstance, DksA acts as a transcription elongation factor in vivo. Chromatin immunoprecipitation (ChIP) experiments were performed by using antibodies against RNA polymerase b subunit in wild-type and DdksA cells treated with 0.5mg/ml serine hydroxamate (SHX) or untreated. DksA and s70 enrichments were compared to RNAP enrichment by ChIP experiments using antibodies against s70 and DksA in wild-type cells (also in DdksA cells as a negative control for DksA ChIP-chip). Differentially labeled ChIP DNA and genomic DNA were competitively hybridized to an E. coli K-12 MG1655 tiling array with overlapping probes at ~12bp spacing across the entire genome. The series contains 19 datasets.
2014-04-21 | E-GEOD-54669 | biostudies-arrayexpress
Project description:<p>The emergence of high-virulent <em>Acinetobacter baumannii</em> strains increases the mortality of patients and seriously affects their prognosis, which motivates us to explore novel ways to control such infections. In this study, gas chromatography-mass spectrometry was adopted to explore the metabolic difference between high- and low-virulent <em>A. baumannii</em> strains, and the decreased L-serine levels were identified as the most crucial biomarker in low-virulent <em>A. baumannii</em> strains. <em>In vitro,</em> L-serine reduced the virulence of <em>A. baumannii</em> to Beas 2B cells and inhibited the activation of NLRP3 inflammasome via decreasing the generation of ROS and mtROS and the release of inflammatory cytokines (IL-18 and IL-1β) through upregulating SIRT1. <em>In vivo</em>, the <em>Galleria mellonella</em> model was adopted. L-serine downregulated the levels of virulence genes (ompA, carO and omp33-36), reduced the mortality of <em>A. baumannii</em> to <em>G. mellonella</em>, and decreased the blacking speed as well as the degree of <em>G. mellonella</em> after infection. Taken together, we found that L-serine can reduce the virulence of <em>A. baumannii</em> and enhance the host’s defense against the pathogen, providing a novel strategy for the treatment of infections caused by <em>A. baumannii</em>.</p>
2024-01-18 | MTBLS8966 | MetaboLights
Project description:The capacity of Acinetobacter baumannii to persist and cause infections depends on its interaction with abiotic and biotic surfaces, including those found on medical devices and host mucosal surfaces. However, the extracellular stimuli affecting these interactions are poorly understood. Based on our previous observations, we hypothesized that mucin, a glycoprotein secreted by lung epithelial cells, particularly during respiratory infections, significantly alters A. baumannii’s physiology and its interaction with the surrounding environment. Biofilm, virulence and growth assays showed that mucin enhances the interaction of A. baumannii ATCC 19606T with abiotic and biotic surfaces and its cytolytic activity against epithelial cells while serving as a nutrient source. The global effect of mucin on the physiology and virulence of this pathogen is supported by RNA-Seq data showing that its presence results in the differential transcription of 427 predicted protein-coding genes. The reduced expression of ion acquisition genes and the increased transcription of genes coding for energy production together with the detection of mucin degradation indicate that this host glycoprotein is a nutrient source. The increased expression of genes coding for adherence and biofilm biogenesis on abiotic and biotic surfaces, the degradation of phenylacetic acid and the production of an active type 6 secretion system further supports the role mucin plays in virulence. Taken together, our observations indicate that A. baumannii recognizes mucin as an environmental signal, which triggers a response cascade that allows this pathogen to acquire critical nutrients and promotes host-pathogen interactions that play a critical role in the pathogenesis of bacterial infections.
2017-12-01 | GSE100582 | GEO
Project description:In bacteria, translation-transcription coupling inhibits RNA polymerase (RNAP) stalling. We present evidence suggesting that, upon amino acid starvation, inactive ribosomes promote rather than inhibit RNAP stalling. We developed an algorithm to evaluate genome-wide polymerase progression independently of local noise, and used it to reveal that the transcription factor DksA inhibits promoter-proximal pausing and increases RNAP elongation when uncoupled from translation by depletion of charged tRNAs. DksA has minimal effect on RNAP elongation in vitro and on untranslated RNAs in vivo. In these cases, transcripts can form RNA structures that prevent backtracking. Thus, the effect of DksA on transcript elongation may occur primarily upon ribosome slowing/stalling or at promoter-proximal locations that limit the potential for RNA structure. We propose that inactive ribosomes prevent formation of backtrackblocking mRNA structures and that, in this circumstance, DksA acts as a transcription elongation factor in vivo.
2014-04-21 | GSE54669 | GEO
Project description:We describe a novel genetic mechanism in which tandem amplification of a plasmid-borne integron regulates virulence, opacity variation, and global gene expression by altering levels of a putative small RNA (sRNA) in Acinetobacter baumannii AB5075. Copy number of this amplified locus correlated with the rate of switching between virulent opaque (VIR-O) and avirulent translucent (AV-T) cells. We found that prototypical VIR-O colonies, which exhibit high levels of switching and visible sectoring with AV-T cells by 24 h of growth, encode two copies of this locus. However, a subset of opaque colonies that did not form AV-T sectors within 24 h were found to encode only one copy. The colonies with decreased sectoring to AV-T were designated low-switching opaque (LSO) variants, and were found to exhibit a three-log decrease in switching relative to the VIR-O. Overexpression studies revealed that the element regulating switching was localized to the 5’ end of the aadB gene within the amplified locus. Northern blotting indicated that a sRNA of approximately 300 nt is encoded in this region, and is likely responsible for regulating switching to AV-T. Copy number of the ~300 nt sRNA was also found to affect virulence, as the LSO variant exhibited decreased virulence during murine lung infections. Global transcriptional profiling revealed that over 100 genes were differentially expressed between VIR-O and LSO variants, suggesting that the ~300 nt sRNA may act as a global regulator. Several virulence genes exhibited decreased expression in LSO cells, potentially explaining their decreased virulence.
2020-08-13 | GSE156206 | GEO
Project description:Strains devoid of ppGpp (ΔrelA ΔspoT; called ppGpp0), and ppGpp0 dksA- exhibit several amino acid requirements for growth on minimal media. We found that overexpression of DksA can complement some of those requirements. Since DksA is a factor that binds to the RNA polymerase secondary channel, we wondered if other secondary channel proteins might also exert a similar role with respect to growth on minimal media. In our study we found that GreA and partially GreB can in fact complement these requirements under certain conditions. Here, we wished to investigate a broader effect of GreA and GreB on ppGpp0 and ppGpp0 dksA- strains. Since the parent strains are unable to grow in minimal media, we had to supplement the M9 glucose medium with a set of amino acids (DFHILQSTV). We found that both, GreA and GreB can affect a much larger set of genes in the absence of dksA, than in its presence. Also, GreA seems to affect more genes than GreB, under both conditions. We used microarrays to detail the effects of overproducing either GreA or GreB in cells devoid of ppGpp, in the dksA+ or dksA- background E. coli cells harbouring plasmids carrying either greA (pA = pHM1873) or greB (pB = pHM1874) genes, or vector control (pGB2), were monitored in an effort to elucidate the effects of their protein products. This was done in two backgrounds- either in E. coli ppGpp0 cells (ΔrelA, ΔspoT) carrying wt dksA gene or a dksA deletion.
2011-10-26 | E-GEOD-28795 | biostudies-arrayexpress