Protein-protein interactions (PPIs) represent an exciting yet challenging class of drug target to have emerged over recent years. With over 300,000 PPIs estimated in humans, and many shown to be implicated in disease, the discovery of small-molecule modulators of these interactions is of great interest. Whilst a vast number of de novo PPI inhibitors such as the Nutlins have been successfully developed, only a handful of complex natural product-derived PPI stabilisers such as paclitaxel (Taxol) have been exploited in the clinic (although to great effect). The number of reported synthetic stabilisers is growing, but the mode-of-action for the vast majority of these examples has been defined in a post hoc fashion. The development of rational strategies for the discovery of de novo PPI stabilisers therefore represents a significant and as yet unmet scientific challenge.
My research is focused on developing chemical biology approaches that will allow us to meet this challenge. Specifically, my interests lie in molecules that act at a given PPI interface and thus (might) act like a ‘molecular glue’. Underpinned by synthetic organic chemistry, two core research avenues focus on enhancing our molecular understanding of PPI stabilisation and establishing improved ligand-discovery techniques.
Better understanding of PPI stabilisation at the atomic level is essential in order to design more synthetically tractable, selective and potent small molecules. To achieve this a combination of in silico evaluation, synthesis, biophysical and structural evaluation is being used to enhance our understanding of natural product PPI stabilisers. As a case in point, the mechanism for fusicoccin A stabilisation of 14-3-3 protein interaction with p53 is not well understood.
The development of assay technologies geared toward the identification of small molecule PPI stabilisers is essential for driving drug discovery. An approach that is currently under investigation seeks to harness the complexity of protein-drug-protein ternary complexes through protein-templated synthesis.
An extension of this work will be to better understand and evaluate small molecule PPI stabilisation in a cellular context. Thus, the development of disease-relevant cell-based assays is of great interest looking into the near future.
Dr Doveston is the supervisor on the below project:
Secondary Supervisor(s): Prof Salvador Macip
University of Registration: University of Leicester
BBSRC Research Themes:
The need for new medicines is greater than ever because of an ageing population and the complex clinical challenges brought about by drug resistance and/or side effects. These problems are particularly acute in the oncology and neurodegeneration therapeutic areas, and this a significant negative impact on society and the economy. As a result, the focus of drug discovery has shifted in recent years away from classical enzyme inhibitors (e.g. kinase inhibitors) to even more challenging targets. Protein-protein interactions (PPI), and in particular inhibitors of these interactions, are at the forefront of this revolution: venetoclax has recently become the first PPI inhibitor approved for the treatment of chronic lymphocytic leukaemia. However, PPI inhibition alone does not fully exploit the potential scope and power of PPIs as drug targets.
Using drugs that act as molecular glues, to stabilise the interaction between proteins, is a highly novel therapeutic strategy that can greatly expand the number, effectiveness and precision of available treatments. This project will build on exciting discoveries in our labs. We have found that covalent, or irreversible, molecular glues that target specific interactions of an important family of ‘hub’ proteins called 14-3-3 is a highly effective strategy for PPI stabilisation that could address a range of disease states including cancer and neurodegeneration.
The aim of the project will be to optimise and refine this therapeutic approach. This will be achieved by studying the role of cysteine amino acids in 14-3-3 proteins. Cysteine is crucial because its nucleophilic properties make it the ideal site for covalent protein modification. In addition, gain of cysteine mutations to 14-3-3 is significant in neurological diseases. We will take an interdisciplinary chemical biology approach to develop more efficacious and selective molecular glues. Ultimately, we aim to deliver new chemical tools for to help further our understanding of disease, and drugs that can be translated into clinical use.
Methodology and Training
The project will be interdisciplinary in nature, combining elements of chemical biology, cellular biology, and structural biology. It will provide excellent training for students who are motivated to go to pursue careers in the fields of drug development, molecular diagnostics, or medical R&D.
Tracking the mechanism of covalent molecular glue stabilization using native mass spectrometry, Carlo J. A. Verhoef, Danielle F. Kay, Lars van Dijck, Richard G. Doveston, Luc Brunsveld, Aneika C. Leney and Peter J. Cossar, Chem. Sci. 2023, 14, 6756-6762.
Contemporary Biophysical Approaches for Studying 14-3-3 Protein-Protein Interactions, B. Thurairajah, A. R. Hudson, R. G. Doveston, Front. Mol. Bioscience, 2022, 9:1043673.
Cooperative Stabilisation of 14-3-3 Protein-Protein Interactions via Covalent Protein Modification, M. Falcicchio, J. A. Ward, S. Y. Chothia, J. Basran, A. Mohindra, S. Macip, P. Roversi, R. G. Doveston, Chem. Sci. 2021, 12, 12985-12992
- Biophysical assays (e.g. fluorescence polarisation, isothermal titration calorimetry, NMR)
- Synthetic chemistry and small molecule characterisation
- Protein X-ray crystallography
- Mass spectrometry
- Cell viability assays
- Western blotting and immunoprecipitation