Project description:The pathogenic bacterium Campylobacter jejuni is the leading cause of bacterial foodborne gastroenteritis worldwide yet it does not grow in the aerobic environment. The paralogues RrpA and RrpB which are members of MarR family of DNA binding proteins have been shown to be important for the survival of C. jejuni under aerobic and redox stress. We report that RrpA is a positive regulator of mdaB, encoding a flavin-dependent quinone reductase. MdaB confers protection to the cell from redox stress mediated by structurally diverse quinones. RrpB negatively regulates the expression of nfrA (Cj1555c), a flavin reductase. NfrA reduces riboflavin at a much higher rate than flavin mononucleotide (FMN),suggesting exogenous free flavins are the natural substrate. Enzymatic activity of MdaB and NfrA towards their substrates revealed both reductases preferred NADPH as an electron donor. DNA-binding and post translational modification analyses showed that the mechanism of RrpA and RrpB DNA binding is likely a cysteine-based redox switch. Complete genome sequences analysis indicated that MdaB is predominant in Campylobacter spp. and the related Helicobacter spp., whilst NfrA is more often found in C. jejuni strains. Quinones and flavins are antimicrobial redox cycling agents secreted by a wide range of cell-types that can form damaging superoxide by one-electron reactions. We propose that MdaB and NfrA production allows a two-electron reduction mechanism to the less toxic quinol forms. These enzymes thus aid the survival and persistence of C. jejuni in the face of toxic compounds from competing microbes.
Project description:We report the use of differential RNA-sequencing for the determination of the primary transcriptome of wildtype Campylobacter jejuni NCTC 11168. This allows for the genome-wide determination of transcription start sites.
Project description:We report the use of differential RNA-sequencing for the determination of the primary transcriptome of the fur perR mutant of Campylobacter jejuni NCTC 11168. This allows for the genome-wide determination of transcription start sites. Campylobacter jejuni NCTC 11168 fur perR mutant was grown to late log phase, RNA was purified and used for differential RNA-sequencing by 454 sequencing with barcoded libraries, and used for determination of genome-wide transcription start sites
Project description:The pathogenic bacterium Campylobacter jejuni is the leading cause of bacterial foodborne gastroenteritis worldwide yet it does not grow in the aerobic environment. The paralogues RrpA and RrpB which are members of MarR family of DNA binding proteins have been shown to be important for the survival of C. jejuni under aerobic and redox stress. We report that RrpA is a positive regulator of mdaB, encoding a flavin-dependent quinone reductase. MdaB confers protection to the cell from redox stress mediated by structurally diverse quinones. RrpB negatively regulates the expression of nfrA (Cj1555c), a flavin reductase. NfrA reduces riboflavin at a much higher rate than flavin mononucleotide (FMN),suggesting exogenous free flavins are the natural substrate. Enzymatic activity of MdaB and NfrA towards their substrates revealed both reductases preferred NADPH as an electron donor. DNA-binding and post translational modification analyses showed that the mechanism of RrpA and RrpB DNA binding is likely a cysteine-based redox switch. Complete genome sequences analysis indicated that MdaB is predominant in Campylobacter spp. and the related Helicobacter spp., whilst NfrA is more often found in C. jejuni strains. Quinones and flavins are antimicrobial redox cycling agents secreted by a wide range of cell-types that can form damaging superoxide by one-electron reactions. We propose that MdaB and NfrA production allows a two-electron reduction mechanism to the less toxic quinol forms. These enzymes thus aid the survival and persistence of C. jejuni in the face of toxic compounds from competing microbes.
Project description:We report the use of differential RNA-sequencing for the determination of the primary transcriptome of the fur perR mutant of Campylobacter jejuni NCTC 11168. This allows for the genome-wide determination of transcription start sites.
Project description:Campylobacter jejuni is the most prevalent cause of foodborne bacterial enteritis worldwide. This study aims at the characterisation of pathomechanisms and signalling in Campylobacter-induced diarrhoea in the human mucosa. During routine colonoscopy, biopsies were taken from patients suffering from campylobacteriosis. RNA-seq of colon biopsies was performed to describe Campylobacter jejuni-mediated effects. Mucosal mRNA profiles of acutely infected patients and healthy controls were generated by deep sequencing using Illumina HiSeq 2500. This data provide the basis for subsequent upstream regulator analysis.
Project description:Background: The food-borne pathogen Campylobacter is one of the most important zoonotic pathogens. Compared to other zoonotic bacteria, Campylobacter species are quite susceptible to environmental or technological stressors. This might be due to the lack of many stress response mechanisms described in other bacteria. Nevertheless, Campylobacter is able to survive in the environment and food products. Although some aspects of the heat stress response in Campylobacter (C.) jejuni are already known, information about the heat stress response in the related species C. coli and C. lari are still unknown. Results: The stress response to elevated temperatures (46°C) was investigated by survival assays and whole transcriptome analyses for the strain C. jejuni NCTC11168, C. coli RM2228 and C. lari RM2100. While C. jejuni showed highest thermotolerance followed by C. lari and C. coli, none of the strains survived at this temperature for more than 24 hours. Transcriptomic analyses revealed that only 3 % of the genes in C. jejuni and approx. 20 % of the genes of C. coli and C. lari were differentially expressed after heat stress, respectively. The transcriptomic profiles showed enhanced gene expression of several chaperones like dnaK, groES, groEL and clpB in all strains, but differences in the gene expression of transcriptional regulators like hspR, perR as well as for genes involved in metabolic pathways, translation processes and membrane components. However, the function of many of the differentially expressed gene is unknown so far. Conclusion: We could demonstrate differences in the ability to survive at elevated temperatures for C. jejuni, C. coli and C. lari and showed for the first time transcriptomic analyses of the heat stress response of C. coli and C. lari. Our data suggest that the heat stress response of C. coli and C. lari are more similar to each other compared to C. jejuni, even though on genetic level a higher homology exists between C. jejuni and C. coli. This indicates that stress response mechanisms described for C. jejuni might be unique for this species and not necessarily transferable to other Campylobacter species.