School of Biological and Chemical Sciences

Designing peptide and small molecule inhibitors for the treatment of Gram-negative bacterial infections

Supervisor: Dr Ewan Main

Project description

The rise of antibiotic resistance is an urgent and growing problem in contemporary medicine. It has emerged as one of the pre-eminent public health concerns of the 21st century. One excellent example of this is the opportunistic pathogen Pseudomonas aeruginosa. It is a major cause of healthcare-associated infections and is increasingly resistant to many antibiotics - it is responsible for 1 in 10 hospital acquired bacterial infections and is one of the most common cause of infection of burn injuries and chronic lung infections in people with cystic fibrosis.

One infection method widely used by Pseudomonas (and many others) involves a protein nanomachine called the Type Three Secretion System (T3SS). In T3SS infection bacteria synthesize toxin proteins and transport them through a channel made of proteins that directly links the insides of the bacteria and host cell. Here the “toxins” modulate host cell signal cascades, which can lead to apoptosis, and thus enable bacterial survival/proliferation. The formation and assembly of the protein channel is critical to infection. The channel complex is comprised of over 20 proteins that combine to form a base in the bacteria, a hollow needle (projects from the bacteria to the host cell) and a pore into the host cell. The needle is composed of one fibre forming protein, whereas the pore is mainly composed of two large transmembrane domain containing proteins (translocators). Importantly, needle and pore formation and thus infection can only occur when the “translocators” are bound by two specific specialized chaperones in the bacterial cytosol. The two translocator/chaperone complexes can then traffic across the bacterial cell membranes, dissociate and then form the needle or the pore. The significance of the translocator/chaperone complex to bacterial pathogenicity is easily highlighted by studies that show chaperone null bacterial strains are non-invasive to eukaryotic cells.

Facilities and training

This PhD studentship seeks to develop and biochemically/biophysically characterise molecules that can bind to T3SS translocator chaperones and disrupt their interactions with their cargo - thus inhibiting the movement of toxins from the bacteria to the host cell. Our long-term aims are to develop these molecules into drug candidates.

This is a truely multi-discipline project: it will involve in the main molecular biology, phage display, recombinant protein production, biochemical/biophysical assays [e.g. C.D. spectroscopy, ITC and NMR]. However this biochemical aspect will be combined with computational simulation/small molecule drug design. As such, it will provide opportunities for training in a wide range of contemporary molecular biology and biochemistry techniques and will equipe the successful applicant with a highly desirable portfolio of laboratory skills and associated transferable skills.

Eligibility and applying

Applicants must contact Dr Ewan Main before submitting an application to discuss their experience, background and the proposed topic.


  • Singh, S.K., Boyle, A.L. & Main, E.R.G. (2013) “LcrH, a class II chaperone from the Type Three Secretion System, has a highly flexible native structure.” Journal of Biological Chemistry, 288 (6), 4048–4055
  • Chatterjee, S., Chaudhury, S., McShan, A.C., Kaur, K. and De Guzman, R.N. (2013) "Structure and Biophysics of Type III Secretion in Bacteria" Biochemistry, 52, 2508-2517
  • Phillips, J.J.P., Millership, C.M., Main, E.R.G. (2012) “Fibrous nanostructures from the self assembly of designed repeat protein modules” Angewandte de Chemie, 51 (52), 13132–13135
  • Rooney, Lisa et al. “Discovery, SAR, and Biological Evaluation of a Novel Class of Potent TRPA1 Antagonists” J. Med. Chem. 2014, 57, 5129-40

See also