Targeting the biosynthesis of a novel Group A Streptococcus virulence factor

Supervisors: Dr Helge Dorfmueller, Prof Mike Ferguson

Project Description
The Helge Dorfmueller (HD) lab is a young lab in the dynamic and vibrant Division of Molecular Microbiology. HD's research focus lies on understanding the molecular details of how the human-exclusive pathogen Streptococcus pyogenes (GAS) synthesises an essential virulence factor. GAS is a severe burden to human life, causing a range of mild and severe, invasive infections, such as necrotising fasciitis (‘flesh-eating disease’) and toxic shock syndrome. These diseases cause very high morbidity and mortality rates with more than 500,000 death / per year worldwide. It is imperative that we need to identify and characterise new drug targets to develop more efficient antibiotics and to prevent a shortfall of antibiotics in the near future.

The HD lab investigates - in close collaboration with the laboratory from Prof. Mike Ferguson - the GAC biosynthesis pathway. Functional and structural characterisation will be conducted to elucidate the catalytic mechanism of this novel virulence factor, to form the basis for future antimicrobial drug development.

The student will conduct fundamental and interdisciplinary research. The project and research training involves molecular microbiology and glycobiology, including cloning, protein expression and purification from recombinant bacterial system and inhibitor screening. Functional characterisation of the enzymes will be carried out using a combination of synthetic biology, bacterial genetics, carbohydrate analysis and enzyme assay development [1]. The Mike Ferguson lab provides expert training in carbohydrate purification and analysis, using biochemistry and mass-spectrometry [2].

The student will be trained in inhibitor screening to identify the first chemical compounds that bind to the target enzyme. We pair glyco-enzymology with structural biology to investigate the kinetic properties of these compounds, which in combination provide the full basis for future structure-based drug design [3]. 

The student will have the opportunity to learn protein crystallisation and high-resolution single crystal X-ray diffraction analysis. These structural studies will reveal detailed insights into the mechanism of catalysis of these novel enzymes and the binding mode of identified inhibitors, providing the basis for future drug discovery programmes.


[1] van der Beek, S. L., Le Breton, Y., Ferenbach, A. T., Chapman, R.N., van Aalten, D.M.F., Navratilova, I., Boons, G.J., McIver, K., van Sorge, N. M. and H.C. Dorfmueller; 'GacA is Essential for Group A Streptococcus and Defines a New Class of Monomeric dTDP-4-dehydrorhamnose Reductases (RmlD)', in print at Molecular Microbiology.

[2] Allen, S., Richardson, J.M., Mehlert, A and Ferguson, M.A.J. (2013) 'Structure of a complex phosphoglycan epitope from gp72 of Trypanosoma cruzi.' J. Biol. Chem. 288, 11093-11105.

[3] Dorfmueller, H.C., Borodkin, V.S., Schimpl, M., and van Aalten, D.M.F. (2009) 'GlcNAcstatins are nanomolar inhibitors of human O-GlcNAcase inducing cellular hyper-O-GlcNAcylation.' Biochem. J., 420(2), 221-7.