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Title: Oxidative stress responses in Campylobacter jejuni : the role of the Peroxide Regulator PerR
Author: Handley, Rebecca Anne
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2013
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Campylobacter jejuni is a microaerophilic foodborne pathogen capable of surviving the stressful, oxygen-exposed route from an avian host and entering into the human food chain. The ability of Campylobacter to survive oxidative stress is thought to contribute to the annual ~500,000 UK cases of campylobacteriosis. One of the main regulatory proteins involved in the protective response of C. jejuni to oxidative stress is the regulatory protein PerR, which regulates gene expression in a metal-dependent manner, controlling the transcription of a set of peroxidases. In this study the perR gene was inactivated and characterised using phenotypic tests and transcriptomic investigations. We investigated the role of PerR in the regulation of oxidative stress defences in C. jejuni and demonstrated that a perR mutant has increased aerotolerance and survival against exposure to oxidative stress. A C. jejuni perR mutant also demonstrated no defect in growth, motility or virulence in the Galleria mellonella insect model. Analysis of microarray data using perR, fur and fur perR mutants allowed the identification of PerR-repressed genes (e.g. ahpC, katA, trxB). Differential RNA sequencing was used to identify target promoters for PerR. Proteomics (2D gel electrophoresis) and gel shift assays were also used to confirm direct regulation by PerR. The combination of these technologies allowed us to focus and hone in on the core members of the PerR regulon. The mechanism by which PerR senses oxidative stress is still unknown, although iron has been suggested to function as co-factor. To investigate this, we expressed and purified C. jejuni PerR in E. coli. Pure PerR was used in biochemical and genetic characterisation experiments including protein crystallography trials and absorption spectrum analysis. iv Further investigations are required into why the perR gene is evolutionary maintained in C. jejuni despite the beneficial nature of its absence for oxidative stress survival.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available