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The foodborne bacterial pathogen Campylobacter jejuni is an obligate microaerophile that is exposed to atmospheric oxygen during transmission through the food chain. Survival under aerobic conditions requires the concerted control of oxidative stress systems, which in C. jejuni are intimately connected with iron metabolism via the PerR and Fur regulatory proteins. Here, we have characterized the roles of C. jejuni PerR in oxidative stress and motility phenotypes, and its regulon at the level of transcription, protein expression and promoter interactions. Insertional inactivation of perR in the C. jejuni reference strains NCTC 11168, 81-176 and 81116 did not result in any growth deficiencies, but strongly increased survival in atmospheric oxygen conditions, and allowed growth around filter discs infused with up to 30 % H2O2 (8.8 M). Expression of catalase, alkyl hydroperoxide reductase, thioredoxin reductase and the Rrc desulforubrerythrin was increased in the perR mutant, and this was mediated at the transcriptional level as shown by electrophoretic mobility shift assays of the katA, ahpC and trxB promoters using purified PerR. Differential RNA-sequencing analysis of a fur perR mutant allowed the identification of eight previously unknown transcription start sites of genes controlled by Fur and/or PerR. Finally, inactivation of perR in C. jejuni did not result in reduced motility, and did not reduce killing of Galleria melonella wax moth larvae. In conclusion, PerR plays an important role in controlling oxidative stress resistance and aerobic survival of C. jejuni, but this role does not extend into control of motility and associated phenotypes.

Original publication

DOI

10.1099/mic.0.000109

Type

Journal article

Journal

Microbiology

Publication Date

07/2015

Volume

161

Pages

1524 - 1536

Keywords

Bacterial Proteins, Campylobacter jejuni, DNA, Bacterial, Electrophoretic Mobility Shift Assay, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Gene Knockout Techniques, Locomotion, Microbial Viability, Mutagenesis, Insertional, Oxidative Stress, Protein Binding, Proteome, Regulon, Repressor Proteins, Stress, Physiological, Transcription Initiation Site, Transcription, Genetic