Copper resistance in salmonella

Lead Research Organisation: University of Manchester
Department Name: Life Sciences

Abstract

Food-borne Salmonella infections cause serious medical and veterinary problems worldwide. In the developed world, salmonellosis continues to be one of the most common forms of food-poisoning and mainly occurs due to the consumption of contaminated animal products. Salmonella food poisoning represents a serious health risk and is usually characterised by the acute onset of fever, abdominal pain, diarrhea, nausea and occasionally vomiting but in some cases the disease can become more severe and life-threatening. Following oral ingestion of Salmonella, disease is started by the bacteria being able to survive within the intestinal tract and invade intestinal cells. The ability of the bacteria to reside in host immune cells (macrophages) is important for their spread to different organs and systemic disease. Survival within the different locations of the host requires that Salmonella can sense and adapt to changing environmental conditions such as varying metal levels. One such metal is copper. Copper is required by Salmonella for several key enzymes but is also extremely toxic. Our preliminary studies have now indicated that resistance to copper-stress plays a vital role during Salmonella infections. This project aims to build upon these studies and provide a detailed characterisation of the mechanisms of copper-resistance in this pathogen and their roles during infection. Furthermore, we will test the hypothesis that copper transporters in host cells contribute to their ability to kill bacteria by supplying copper to generate highly toxic reactive oxygen species. Understanding the environmental challenges that occur in the infected host and the mechanisms which protect Salmonella from copper stress may help in developing novel therapeutics to combat disease. Furthermore, there is a growing use of copper as a means of controlling bacterial growth in agriculture and the food industry. Clearly this has implications for the development of more resistant bacteria. Hence, a thorough understanding of the copper-resistance systems in Salmonella and their role in virulence is vital.

Technical Summary

This programme of work will test the hypothesis that the copper-resistance systems in Salmonella enterica serovar Typhimurium play an important role in pathogenicity. Obtaining copper for loading onto copper-dependent enzymes is a vital requirement for S. Typhimurium during infection. However, copper is extremely toxic and indeed is now thought to constitute a crucial component of the bacterial killing mechanisms within a host. S. Typhimurium must therefore possess systems that ensure a supply of copper to copper-requiring proteins whilst avoiding copper-toxicity. Our preliminary studies have shown that the cue and gol systems in S. Typhimurium both have roles in providing protection from copper-stress. We now intend to perform a detailed characterisation of these systems and examine the roles of the cue and gol proteins in copper-sensing, -transport and -trafficking under different stress conditions. It is anticipated that the possession of these two systems provides S. Typhimurium with the ability to adapt to excess cytoplasmic copper under different surplus copper conditions encountered at different locations within a host. This will be investigated. We will also test the hypothesis that mammalian copper transporters contribute to the anti-bacterial activity of macrophages by supplying copper for the Fenton reaction and hence the generation of deadly hydroxyl radicals. With the widespread use of copper to control microbial growth in agricultural practices and the food industry, a thorough investigation of the copper-resistance systems in S. Typhimurium and their role in virulence is both timely and necessary. It is anticipated that an understanding of the roles of the copper-resistance systems in S. Typhimurium infection could enhance the development of new drugs and control strategies.

Publications

10 25 50
 
Description Salmonella is one of the most common causes of food-borne disease in man and represents a serious health risk. Disease mainly occurs due to the consumption of contaminated animal products and is usually characterised by the acute onset of fever, abdominal pain, diarrhoea, nausea and occasionally vomiting, but in some cases the disease can become more severe and life-threatening. The ability of Salmonella to cause disease is associated with its ability to survive and replicate inside the antimicrobial compartments, known as phagosomes, of host immune cells (macrophages). In this study we established that high copper levels are a feature of macrophage phagosomes and in response to bacterial infection macrophages increase production of their copper-transporters to concentrate copper within these compartments and exploit copper-toxicity in their anti-microbial defences. We demonstrated that Salmonella possesses two related copper-exporting proteins, CopA and GolT, and both have a role in copper resistance. Importantly, copper-resistance due to copper-export by CopA or GolT, is required for pathogen survival in macrophage phagosomes. In addition to a role in copper-resistance, we also demonstrated that both CopA and GolT are required in the copper-supply pathway for periplasmic Cu,Zn-superoxide dismutase (SOD). This is the first evidence of a copper-trafficking pathway for the activation of a periplasmic Cu,Zn-SOD. We identified a novel protein CueP as an abundant periplasmic copper-binding protein also required in the copper supply pathway for Salmonella Cu,Zn-SOD activation. Copper is directly transferred from Cu-CueP to pre-folded Zn-SOD to generate the active enzyme, implicating CueP as a copper-chaperone.
Exploitation Route The discovery that copper contributes to innate immune defences and that copper-resistance contributes to the ability of microbes to cause infections is being exploited in the development of copper-related antimicrobials.

We have identified novel copper-homeostatic proteins in Salmonella that represent targets for antimicrobial drug-development.

The copper-supply pathway that we have uncovered in Salmonella represents a paradigm system and knowledge of this system may be applied to improving small molecule, bioenergy industrial biotechnology and potentially bioprocessing applications.
Sectors Agriculture, Food and Drink,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

 
Description Public engagement activities with findings of this research: Used as an example to support the A-level syllabus via an article in the 'Biological Sciences Review' magazine for sixth formers (2014) Presented in a lecture to year 12 school pupils - Discover Life Sciences (2016).
First Year Of Impact 2014
Sector Education
Impact Types Societal

 
Description Advanced Life Sciences Research Technology Initiative
Amount £409,319 (GBP)
Funding ID BB/L014823/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2014 
End 03/2014
 
Description Food-borne Listeria infections: Zinc homeostasis at the host-pathogen interface
Amount £483,000 (GBP)
Funding ID BB/K016881/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2014 
End 01/2017
 
Description Metal-sensing in Salmonella: A model for targeting a network that differentiates metals
Amount £759,000 (GBP)
Funding ID BB/J017787/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 10/2012 
End 10/2017
 
Description Responsive mode
Amount £713,334 (GBP)
Funding ID BB/R010412/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 03/2018 
End 03/2021
 
Description Collaboration Leicester 
Organisation University of Leicester
Country United Kingdom 
Sector Academic/University 
PI Contribution Research collaboration leading to publications and future funding
Collaborator Contribution Research collaboration leading to publications and future funding
Impact Publications in research journals (Corbett et al., 2011 & 2012) and future funding (BB/K016881/1)
Start Year 2010
 
Description International collaboration 
Organisation Indiana University
Country United States 
Sector Academic/University 
PI Contribution Research collaboration leading to publication
Collaborator Contribution Research collaboration leading to publication
Impact Publication in research journal (Wang et al., 2010)
Start Year 2009
 
Description Article for Biological Sciences Review 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Article for Biological Sciences Review (2014) Salmonella: A bacterial pathogen that invades our gut. Aimed at 6th formers to support A level syllabus and has resulted in requests for visits/placements from 6th formers.

None so far
Year(s) Of Engagement Activity 2014
 
Description British Science Week 2013 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact NOWGEN DNA stand at Science Extravaganza for British Science Week (a 10 day event with engaging activities for people of all ages) - the activity was at Manchester Museum and hosted as a public event
Year(s) Of Engagement Activity 2012
 
Description Copper Homeostasis and Salmonella Pathogenesis 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation poster presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited speaker Invited speaker, Gordon Research Conference (GRC), Cell Biology of Metals, Rhode Island, USA.

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description FLS open day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Managing an interactive 'Exploring DNA Stand' at a faculty of life sciences (University of Manchester) community open day - aimed at engaging with the local community, The presentation sparked questions and discussions.
Year(s) Of Engagement Activity 2013
 
Description Lecture to year 12 school pupils 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Research findings were presented to ~20 year 12 school pupils who visited the research organisation
Year(s) Of Engagement Activity 2014
 
Description NorthWest Microbiology 2011 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Speaker at North West Microbiology meeting aimed at young researchers - talk sparked questions and possible collaborations

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description NorthWest Microbiology 2012 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Presentations at North West Microbiology meeting aimed at young researchers - presentations sparked questions and possible collaborations
Year(s) Of Engagement Activity 2012
 
Description Presentation at the 10th International Copper Meeting (2016) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Poster presentation by researcher and postgraduate student at the 10th International Copper Meeting (Sorrento, Naples, Italy)
Year(s) Of Engagement Activity 2016
 
Description Supervision of a Nuffield Research Placement 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Engagement of school 6th former in primary research - influenced career plans

After this placements there have been requests to host future Nuffield placements
Year(s) Of Engagement Activity 2012