Oxidative stress responses in Campylobacter jejuni: the role of the Peroxide Regulator PerR

Handley, Rebecca Anne (2013) Oxidative stress responses in Campylobacter jejuni: the role of the Peroxide Regulator PerR. Doctoral thesis, University of East Anglia.

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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.
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.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Users 2259 not found.
Date Deposited: 12 Jun 2014 13:24
Last Modified: 12 Jun 2014 13:24
URI: https://ueaeprints.uea.ac.uk/id/eprint/48754


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