Location: Streatham Campus

This project is one of a number that are in competition for funding from the South West Doctoral Training Partnership (SWDTP). The SWDTP involves the four research-intensive universities across the South West - Bath, Bristol, Cardiff and Exeter – and Rothamsted Research. For further details about the programme please see http://www.bristol.ac.uk/swdtp/swdtp_about/.

Supervisors:

Dr Alan Brown, University of Exeter

Dr Steve Porter, University of Exeter

Project description:

Background

The Burkholderia genus includes species with great biotechnological potential as bioremediation agents, biopesticides and crop growth-promoting agents. They are frequently isolated from heavy metal-contaminated soils, including agricultural soils in which heavy metals accumulate through the addition of mineral fertilisers and copper-based pesticides. Consequently, Burkholderia possess efficient protective mechanisms that guard against metal toxicity. We have recently characterized one such mechanism - the CzcRS two-component system (TCS) of Burkholderia cenocepacia which confers zinc and cadmium resistance through the regulation of the CzcCBA efflux pump. In addition, we have shown that the CzcRS system also plays a pivotal role in the virulence of B. cenocepacia. We have also identified two other putative heavy metal-responsive TCSs that we predict form a novel multi-kinase network with the CzcRS system (based on shared specificity-determining residues) which could enable cells to modulate responses to certain heavy metals depending on the other stressors present. Furthermore, our studies have revealed a cluster of three genes that encodes a novel putative heavy metal resistance determinant that may form part of the CzcR regulon.

Research Programme

Through a multidisciplinary programme of research combining biochemistry, molecular bacteriology and genomics, the student will:

• define the hierarchy and interconnectedness of the TCS regulatory networks that mediate heavy metal tolerance in Burkholderia;
• identify & characterize the resistance determinants controlled by these networks.

In the first year, rotation projects will be undertaken with Drs Steve Porter and Alan Brown. The first of these will use bioinformatics methods to predict metal-responsive multi-kinase networks in metal-tolerant Burkholderia and non-Burkholderia species, and perform experimental validation on selected systems using phosphorylation assays. In the second rotation project, the student will investigate the putative novel heavy metal resistance determinant referred to above through the targeted deletion of each gene within the three-gene cluster and phenotypic characterization of the resulting mutants.

Thereafter (years 2-4), the student will (a) generate single, double and triple deletion mutants of the three TCSs of interest and assess relevant phenotypes; (b) generate reporter strains in wildtype and deletion mutant backgrounds to assess the transcriptional activity of each TCS and their interdependence; (c) biochemically investigate direct interactions between kinases and response regulators of the putative multi-kinase network, and (d) define and characterize the regulon of each TCS using ChIP-seq methodology.

Conclusion

The project, which offers outstanding training opportunities in diverse methodologies, will reveal the complex regulatory networks and downstream effectors of heavy metal resistance in Burkholderiaspecies, and will provide novel insight into the wider role of metal-responsive multi-kinase networks in environmentally-important bacterial species.

For further information and eligibility please visit:  

http://www.exeter.ac.uk/studying/funding/award/?id=1625

Funding:

For eligible students the award will cover UK/EU tuition fees and an annual stipend (in 2014/15 this was £13,863 for full-time students, pro rata for part-time students) for three and a half years.

Citizens of a EU member state will be eligible for a fees-only award.