Exploitation of quorum sensing for the discovery of novel agents against staphylococci
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Molecular Sciences
Abstract
The emergence, rapid spread and persistence of multi-antibiotic resistant bacteria constitutes a global health threat. The World Health Organization has stated that ?no population is more vulnerable to multi-antibiotic resistance than those admitted to hospital wards?. In the UK, healthcare associated infections account for over 5000 deaths annually and are associated with enormous personal and financial costs to the individual, their family and to the NHS (estimated at over #1 billion p.a.). In this context, both hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) and Clostridium difficile are particularly problematic. This is not only a consequence of their ability to cause disease but also because antibiotic usage increases resistance and infection rates. Recently new ?community acquired? MRSA strains (CA-MRSA) have emerged which cause invasive infections in healthy young people. Against this backdrop, the development of new classes of antibiotics has lagged far behind the urgent requirement for new drugs, in part because of the reluctance of major pharmaceutical companies to develop expensive new drugs likely to become rapidly obsolete through resistance. Consequently we need to gain better insights into the infection-specific lifestyle of bacteria if we are to discover new ways of preventing and treating infection and reducing the selection of resistant strains. In this project we are seeking to understand how MRSA bacteria use chemical signals to communicate with each to make decisions about when to deploy the armoury of toxins they need to fight off human host defences, grow inside human cells and damage tissues. By understanding the chemical nature of these signals, the way in which they are produced by the bacterial cell and sensed by receptor proteins on the bacterial cell surface we will develop new drug molecules capable of controlling infection by blocking this signalling system. So far we have discovered three different families of small molecules which either inhibit signalling or growth or both. We will therefore use medicinal chemistry and biological approaches to understand how these compounds work at the molecular level and use this information to design agents with increased potency in antibacterial assays in the laboratory. The most promising compounds will be tested for efficacy in experimental animal infection models. The work with focus on primarily MRSA but promising compounds will also be tested against C. difficile and related pathogens.
Technical Summary
Staphylococcal infections are of major clinical importance. MRSA strains which exhibit multi-antibiotic resistance and cause invasive infections in healthy individuals constitute a serious health threat. While resistance has evolved against virtually every antibiotic deployed, the development of new classes of antibiotics has lagged far behind the urgent requirement for new drugs. Many major pharmaceutical companies have withdrawn from the antibiotic discovery field mainly because of the huge economic cost of developing drugs likely to become rapidly obsolete through resistance. Thus, there is an urgent need to identify novel antibacterial targets and develop new agents effective against multi-resistant bacteria. This in turn depends on a thorough understanding of the basic molecular biology and physiology of bacterial pathogens. In this context, the attenuation of virulence through the blockade of sophisticated global regulatory systems such as quorum sensing (QS) offers an attractive target. In S. aureus, the agr QS system, which is also shared by Gram positive pathogens including Listeria, Enterococcus and Clostridium, is central to virulence gene regulation, intracellular survival and biofilm development and dispersal. Here we propose to build on our previous work by employing a multidisciplinary research strategy combining chemical biology with bacterial physiology and in vivo studies to obtain detailed molecular insights into (a) the recognition of auto-inducing peptide (AIP) signal molecules by the histidine sensor kinase receptor, AgrC, and (b) the generation and export of AIPs via the transmembrane enzyme, AgrB. Unexpectedly, both growth and agr-dependent QS in S. aureus can be inhibited by Gram negative bacterial QS signal molecules and we have discovered analogues (tetramic and tetronic acids) which exhibit potent activity against staphylococci and other Gram positive bacteria including Clostridium difficile. In addition we have identified a class of thiol-reactive aryl quinones which inhibit agr potentially through the inactivation of SarA family proteins in S. aureus which regulate virulence via agr-dependent and -independent mechanisms. We will therefore undertake extensive structure activity relationship, mechanistic and translational studies on the each compound class to elucidate their mechanisms of action and to develop agents with increased potency. The most promising compounds including novel AIP antagonists will be investigated for their activity against planktonic, biofilm and intracellular staphylococci in laboratory culture and for in vivo efficacy in experimental animal infection models. The work has broad implications for antibacterial agent discovery beyond S. aureus given the conservation of agr systems in Gram positive pathogens and two component systems in bacteria generally
Publications

Betts HM
(2016)
Synthesis, in Vitro Evaluation, and Radiolabeling of Fluorinated Puromycin Analogues: Potential Candidates for PET Imaging of Protein Synthesis.
in Journal of medicinal chemistry

Chan WC
(2004)
Virulence regulation and quorum sensing in staphylococcal infections: competitive AgrC antagonists as quorum sensing inhibitors.
in Journal of medicinal chemistry


Desouky SE
(2013)
High-throughput screening of inhibitors targeting Agr/Fsr quorum sensing in Staphylococcus aureus and Enterococcus faecalis.
in Bioscience, biotechnology, and biochemistry

Doherty N
(2006)
Functional analysis of luxS in Staphylococcus aureus reveals a role in metabolism but not quorum sensing.
in Journal of bacteriology

Doherty NC
(2010)
In Helicobacter pylori, LuxS is a key enzyme in cysteine provision through a reverse transsulfuration pathway.
in Journal of bacteriology

Frees D
(2004)
Clp ATPases are required for stress tolerance, intracellular replication and biofilm formation in Staphylococcus aureus.
in Molecular microbiology

Gardiner L
(2005)
Discovery of antagonist peptides against bacterial helicase-primase interaction in B. stearothermophilus by reverse yeast three-hybrid.
in Chemistry & biology

Gordon CP
(2013)
Attenuating Staphylococcus aureus virulence gene regulation: a medicinal chemistry perspective.
in Journal of medicinal chemistry

Harraghy N
(2005)
sae is essential for expression of the staphylococcal adhesins Eap and Emp.
in Microbiology (Reading, England)
Description | MRC Programme Grant |
Amount | £1,690,000 (GBP) |
Funding ID | G9219778 |
Organisation | Medical Research Council (MRC) |
Sector | Public |
Country | United Kingdom |
Start | 06/2009 |
End | 06/2014 |
Title | Bacterial Intracellular Growth Assay |
Description | We developed an in vitro high throughput cell culture-based method to investigate the intracellular behaviour of bacteria such as the staphylococci and for screening the intracellular efficacy of antimicrobial agents |
Type Of Material | Technology assay or reagent |
Provided To Others? | Yes |
Impact | Joint publications with other EU research groups |
Title | Quorum Sensing Inhibitors |
Description | A chemical library of compounds has been synthesized and screened for the ability to inhibit staphylococcal virulence through the inhibition of quorum sensing. Information on the compounds and their physico-chemical properties are available in: Murray EJ, Crowley RC, Truman A, Clarke SR, Cottam JA, Jadhav GP, Steele VR, O'Shea P, Lindholm C, Cockayne A, Chhabra SR, Chan WC, Williams P. (2014) Targeting Staphylococcus aureus quorum sensing with non-peptidic small molecule inhibitors. J Med Chem. 57(6):2813-9. |
Type Of Material | Technology assay or reagent |
Year Produced | 2014 |
Provided To Others? | Yes |
Impact | The lead compound was tested in vitro and in vivo as an alternative to antibiotics for prevent catheter associated blood stream infections Details were published in; Zapotoczna M, Murray EJ, Hogan S, O'Gara JP, Chhabra SR, Chan WC, O'Neill E, Williams P. (2017) 5-Hydroxyethyl-3-tetradecanoyltetramic acid represents a novel treatment for intravascular catheter infections due to Staphylococcus aureus. J Antimicrob Chemother. 72:744-753. |
URL | https://pubs.acs.org/doi/10.1021/jm500215s |
Description | Agr-dependent quorum sensing and methicillin resistance |
Organisation | University of Bath |
Department | Department of Biology and Biochemistry |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Intellectual contribution, experimental design and synthesis of quorum sensing signal molecules |
Collaborator Contribution | Joint experimental work leading to a publication |
Impact | Publication in press in Journal of Infectious Diseases (2010) |
Start Year | 2010 |
Description | Eap and Emp proteins |
Organisation | Saarland University |
Department | Institute of Medical Microbiology and Hygiene |
Country | Germany |
Sector | Academic/University |
PI Contribution | application of the intracellular staphylococcal assay to evalute contribution of Eap and Emp proteins to growth |
Collaborator Contribution | Collaborative experiments on the role and regulation of the staphylococcal cell wall proteins Eap and Emp |
Impact | Joint Publication - see section 2 |
Description | Intracellular assays and Clp proteases |
Organisation | University of Copenhagen |
Department | Royal Veterinary and Agricultural University |
Country | Denmark |
Sector | Academic/University |
PI Contribution | Application of intracellular replication assays to the role of staphylococcal clp proteases |
Collaborator Contribution | Collaboration on the role of Clp ATPases in stress tolerance, intracellular replication and biofilm formation in Staphylococcus aureus |
Impact | Joint Publication - see section 2 |
Description | Mathematical Modelling of Quorum Sensing |
Organisation | University of Nottingham |
Department | School of Mathematical Sciences Nottingham |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Input of biological knowledgene into the development of mathematical models |
Collaborator Contribution | Development of mathematical models of bacterial virulence gene regulation |
Impact | Publications - see section 2 |
Start Year | 2006 |
Description | BBC1 Programme 'Bang goes the Theory' |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Paul Williams gave an interview in his Nottingham laboratory on quorum sensing and novel antibiotics filmed for Series 3 Episode 4 of 'Bang goes the Theory'. Specific Viewing figures for the episode broadcast on 4 April 2011 not known but audiences of 2-3 million per episode have been reported. None identified as yet |
Year(s) Of Engagement Activity | 2011 |
Description | Electronic Encyclopedia Article |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | On-line article on quorum sensing for the Encyclopaedia of Life Sciences. See:(http://mrw.interscience.wiley.com/emrw/9780470015902/els/article/a0001426/current/html?hd%3DAll%2Cquorum) Not known |
Year(s) Of Engagement Activity | 2007 |
URL | http://mrw.interscience.wiley.com/emrw/9780470015902/els/article/a0001426/current/html?hd%3DAll%2Cqu... |
Description | Media Briefing - Science Media Centre |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Press interview given on antibiotics and antibiotic resistance at the Science Media Centre in London to newspaper science journalists None known |
Year(s) Of Engagement Activity | 2007 |
Description | Nottingham Welsh Society |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Type Of Presentation | Keynote/Invited Speaker |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | About 30 people attended the presentation on 'plagues - ancient and modern in which I talked about antibiotic resistance MRSA and C.difficile. The talk was followed by a lively Q&A session None known |
Year(s) Of Engagement Activity | 2012 |
Description | Public Art and Science Workshop |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | A presentation on microbes and quorum sensing at a public workshop entitled 'Discovering the invisible - photography in art and science at the Lakeside Theatre Nottingham (30th June 2007). Not known |
Year(s) Of Engagement Activity | 2007 |
Description | Quorum Sensing Web Site |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | We established a web site (www.nottingham.ac.uk/quorum) which explains the basics of bacterial cell-cell communication for both public and specialist audiences, It also acts as a one stop shop linking all those working or interested in the field. The site has received 73943 hits since September 2006 and has been approved by the Thomson Thompson ISI Current Web site for its authority, accuracy, currency, navigation and design and quality of writing |
Year(s) Of Engagement Activity | 2006,2007,2008,2009 |
URL | http://www.nottingham.ac.uk/quorum |
Description | Radio 4 Programme |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Contributions made to a 2 part BBC Radio 4 programme on the "Rise of Resistance" Part 1 and 2 with Dr Mark Porter (brodacast on 04/07/07 and 11/04/07) Not known |
Year(s) Of Engagement Activity | 2007 |
Description | University Access |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Over the last 3 years (Feb 2007, 2008 and 2009) contributions to have been made to the "Get on 4 Uni Masterclasses "which give Year 12 students the opportunity to develop interdisciplinary approaches to learning and to explore, in depth, subjects that they may be interested in studying at university. Not known |
Year(s) Of Engagement Activity | 2007,2008 |