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Investigating the efficacy of new lactamase inhibitors against Mycobacteria sp

Primary Supervisor: Dr Jonathan Cox, Life & Health Sciences

Secondary supervisor:Dr Dan Rathbone (Aston University) and Dr Luke Alderwick (University of Birmingham)

PhD project title: Investigating the efficacy of new beta-lactamase inhibitors against Mycobacteria sp.

University of Registration: Aston University

Project outline:

Mycobacteria sp. are acid-fast rod-shaped bacilli that can cause a variety of human and animal infections, some with zoonotic capabilities. These organisms are hard to treat due to their complex, hydrophobic cell wall that acts as a physical barrier to most classes of antibiotic. Beta-lactam antibiotics are capable of penetrating the mycobacterial cell wall, but are extensively ineffective due to a highly conserved beta‑lactamase enzyme that hydrolyses the antibiotics rendering them ineffective. Improving our understanding of mycobacterial beta-lactamases and developing novel strategies to inhibit these enzymes in mycobacterial could revolutionise the treatment of mycobacterial infections. Recent studies have demonstrated the use of clavulanic acid to reverse the resistance of Mycobacterium tuberculosis to carbapenem antibiotics1, however this competitive beta-lactam-based beta-lactamase inhibitor is not effective against other mycobacterial beta-lactamases2.

At Aston University, we have developed a new class of beta-lactamase inhibitor with activity against Mycobacteria sp. We know that members of this new class of lactamase inhibitor are able to penetrate the mycobacterial cell wall and we have shown that they can inhibit the enzymatic function of the beta-lactamase from Mycobacterium abscessus, but we have no knowledge of their activity across other pathogenic species. Furthermore, we do not know the most appropriate beta-lactam to partner with these beta-lactamase inhibitors. Finally, we are in the process of synthesising a library of these molecules and would like to conduct a structure-activity relationship (SAR) screen better to understand the compound-target interaction, in order to optimise our ‘hit’ compound into a ‘lead’ which can be further tested for toxicity and efficacy against intracellular bacteria.

The preliminary aims of this PhD Studentship will be:

  1. To determine the spectrum of activity of our new beta-lactamase inhibitors using both biochemical and phenotypic approaches.
  2. To test all newly synthesised compounds using biochemical, phenotypic and in-silico analysis in order to conduct the SAR screen and develop a ‘lead’ compound.
  3. To establish the synergy of our active compounds alongside all commercially available beta-lactam, carbapenem, cephalosporin and monobactam drugs.
  4. To establish the frequency of resistance of active inhibitors, to study their toxicity and to determine the intracellular activity of the ‘lead’ compound.

This project will focus on improving our understanding of this new beta-lactamase inhibitor series, benefiting from the biochemical, microbiological and medicinal chemistry expertise of the supervisory team. Although this project will be led at Aston University and hosted by the Mycobacterial Research Group led by Dr Jonathan Cox, there will be opportunities for BSL-3 training and the provision of experiments in M. tuberculosis at the University of Birmingham under the co-supervision of Dr Luke Alderwick who runs that facility. Furthermore, training in in-silico drug design and molecular dynamics will be provided by Dr Dan Rathbone.

All training required for this project will be provided by the supervisory team including: molecular genetics, recombinant protein production and purification, biochemical assays, microorganism handling, MIC, MBC and synergy testing, structural biology and in-silico drug design and molecular dynamics as well as all relevant health and safety training.

References:

  1. England et al. (2012). Meropenem-Clavulanic Acid Shows Activity against Mycobacterium tuberculosis In Vivo. Antimicrob. Agents Chemother. 56(6): 3384–3387.
  2. Soroka, D. et al. (2017). Inhibition of beta-lactamases of mycobacteria by avibactam and clavulanate. J. Antimicrob. Chemother. 72(4):1081-1088 doi: 10.1093/jac/dkw546.

BBSRC Strategic Research Priority: Integrated Understanding of Health: Pharmaceuticals: Understanding the rules of life: Microbiology

Techniques that will be undertaken during the project:

  • Cloning
  • Recombinant protein production and purification
  • Biochemical assays
  • Microorganism handling
  • Minimal inhibitory concentration (MIC) determination
  • Minimal bactericidal concentration (MBC) determination
  • Synergy testing
  • Enzyme assays and kinetics
  • Structural biology
  • in-silico drug design
  • Molecular dynamics

Contact: Dr Jonathan Cox, Aston University