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Role of DksA in the pathogenesis and physiology of Campylobacter jejuni.

ABSTRACT: 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

ORGANISM(S): Campylobacter jejuni subsp. jejuni 81-176 Campylobacter jejuni

PROVIDER: GSE9866 | GEO | 2008/05/06

SECONDARY ACCESSION(S): PRJNA103851

REPOSITORIES: GEO

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Role of DksA in the pathogenesis and physiology of Campylobacter jejuni.

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

Transcriptional profiling of Campylobacter jejuni wild-type 81-176 and its ciprofloxacin-resistant derivative (P3) in the presence and absence of ciprofloxacin

Project description:Campylobacter jejuni is one of the most important zoonotic enteric bacterial pathogens able to colonize the gastrointestinal tract of various animals. The number of campylobacteriosis cases has increased worldwide and the particular concern has been the high level of fluoroquinolone resistance observed in C. jejuni isolates. In this study, we explored the effect of ciprofloxacin in Campylobacter jejuni by gene expression microarray analysis. The comparisons of transcriptional responses were performed in the absence and presence of ciprofloxacin with the wild-type strain 81-176 and its intermediate-resistant variant (P3). The resistant variant contained a single-nucleotide mutation causing amino acid change Asp-90-Asn in the gyrA gene instead of the most common Thr-86-Ile, causing a high-level resistance to ciprofloxacin. After the short-term exposure to a relatively high concentration of ciprofloxacin, the viability of C. jejuni 81-176 wild-type cells remained notably high when compared with other gram-negative bacteria. The general responses of short-term ciprofloxacin exposure were determined from both genetic backgrounds and resulted in the expression variation of genes participating in general cellular processes, e.g. , in carbon and amino-acid metabolism and protein transport.

2012-12-31 | GSE41822 | GEO

DksA acts as a transcriptional switch in stress and virulence in Acinetobacter baumannii

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

Transcriptional profile in the macrolide resistant C. jejuni strains selected from 81-176

Project description:Campylobacter, a major foodborne pathogen, is increasingly resistant to macrolide antibibotics. previous findings suggeted that development of macrolide resistance in campylobacter requires a multi-step process, but the molecular mechanisms involved in the process are not known. In our study, multiple seriess of macrolide-resistant C. jejuni mutants were selected in vitro by stepwise exposure of C. jejuni 81-176 to increasing concentrations of erythromycin and tylosin. A set of the selected resistance were subjected to microarray and the the global transcriptional profile was analyzed. In this sery, DNA microarray was used to compare the gene expression profiles of macrolide resistant strains (76E2, 76E8 and 76E64) with its parent wild-type strain C. jejuni 81-176. This assay identified a large number of genes that showed >1.5 fold changes (q-value<0.1) in expression in the macrolide resistant strains. The up-regulated genes are involved in surface structure,ribosomal, heat shock and some specific Misc memerbrane , while the majority of the down-regulated genes are involved in energy metabolism, amino acid biosynthesis. The over-expression of genes involved in surface structure and Misc memerbrance was associated with the development of intermedial-level resistance to macrolide in campylobacter 81-176. Keywords:intermedial-level macrolide resistant C. jejuni selected from C. jejuni 81-176. step-wise selection.

2010-12-28 | GSE17899 | GEO

Transcriptional profile in the macrolide resistant C. jejuni strains selected from 81-176

2010-12-28 | E-GEOD-17899 | biostudies-arrayexpress

Campylobacter jejuni demonstrates conserved proteomic and transcriptomic responses when co-cultured with human INT 407 and Caco-2 epithelial cells

Project description:Major foodborne bacterial pathogens, such as Campylobacter jejuni, have devised complex strategies to establish and foster intestinal infections. For more than two decades researchers have used immortalized cell lines derived from human intestinal tissue to dissect C. jejuni-host cell interactions. Known from these studies is that C. jejuni virulence is multifactorial, requiring a coordinated response to produce virulence factors that facilitate the bacterium’s host-cell interactions. This study was initiated to identify C. jejuni proteins that contribute to adaptation to the host cell environment and cellular invasion. We demonstrated that C. jejuni responds to INT 407 and Caco-2 cells in a similar fashion at the cellular and molecular levels. Active protein synthesis was found to be required for C. jejuni to maximally invade these host cells. Proteomic and transcriptomic approaches were then used to define the protein and gene expression profiles of C. jejuni co-cultured with cells. By focusing on those genes showing increased expression by C. jejuni when co-cultured with epithelial cells, we discovered that C. jejuni quickly adapts to co-culture with epithelial cells by synthesizing gene products that enable it to acquire specific amino acids for growth, scavenge for inorganic molecules including iron, resist reactive oxygen/nitrogen species, and promote bacteria-host cell interactions. Based on these findings, we selected a subset of the genes involved in chemotaxis and the regulation of flagellar assembly and generated C. jejuni deletion mutants for phenotypic analysis. Binding and internalization assays revealed significant differences in the interaction of C. jejuni chemotaxis and flagellar regulatory mutants. The identification of genes involved in C. jejuni adaptation to culture with host cells provides new insights into the infection process.

2019-04-11 | GSE114909 | GEO

Understanding the roles of dksA and greA in inorganic polyphosphate accumulation in Escherichia coli

Project description:Inorganic polyphosphate (polyP) is synthesized by bacteria in response to various stresses, but the mechanism of its regulation is unknown. Mutants of Escherichia coli lacking the RNA polymerase-binding transcription factor dksA are defective in polyP synthesis after a nutrient limitation stress, and this defect is reversed in a dksA greA mutant. In this work, we used RNA sequencing to compare transcription in wild-type, dksA, and dksA greA strains of E. coli before and after nutrient limitation, to identify genes whose expression pattern correlates with ability to synthesize polyP.

2020-03-11 | GSE144816 | GEO

Transcriptional profiling of Campylobacter jejuni wild-type 81-176 and its ciprofloxacin-resistant derivative (P3) in the presence and absence of ciprofloxacin

2012-12-31 | E-GEOD-41822 | biostudies-arrayexpress

The interplay between a protein and an mRNA antagonist controls CsrA-mediated regulation of flagella genes in Campylobacter jejuni

Project description:This study investigates the CsrA regulon of the food-borne pathogen Campylobacter jejuni. Direct RNA binding targets of CsrA in two strains of C. jejuni, NCTC11168 and 81-176, were determined using RIP-seq.

2016-04-07 | GSE58419 | GEO

DksA Guards Elongating RNA Polymerase Against Ribosome-Stalling-Induced Arrest

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

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