Membrane proteins have major roles in a wide range of biological functions including uptake of essential nutrients, export of toxins and waste products and mediating the cellular responses to a variety of biologically active molecules including many drugs. Our understanding of these important proteins is currently limited by a lack of high resolution structures. Recent research in our group in collaboration with Dr Alexander Cameron, University of Warwick and Prof George Diallinas, University of Athens solved the structure of the dimer of UapA, an integral membrane transporter from Aspergillus nidulans. This provided detailed insights into the mechanism of action of the protein as well as shedding light on how individual transporter molecules in a dimer arrangement can affect each others function.
The structure-function studies of integral membrane proteins however continues to be a major challenge. These proteins are difficult to express using recombinant technologies. Their highly hydrophobic and often dynamic nature makes them unstable in solution. In addition, the requirement that they are maintained in solution as detergent-protein micelles makes them significantly less likely to crystallize than soluble proteins. One key focus of my group is the development of methodologies and techniques to facilitate the production of stable protein for structural studies. This includes the development of specific protocols for large- scale production of stable, functional membrane protein and the characterization of novel amphiphiles to increase the stability of membrane proteins prior to and during crystallization. Our membrane protein research involves collaborators from Imperial College, University of Manchester, Kings College London, University of Warwick, Hanyang University, Korea and University of Athens, Greece.
Functional analysis of the human adenosine A2AR reveals insight into its mechanism of action (Bertheleme et al, 2013, 2014).
Other research has focused on the development and characterisation of novel amphiphiles for solubilisation and stabilisation of integral membrane proteins. This has lead to a number of high profile publications, the latest of which was featured as a cover image for Chem Comm.
An additional activity of the group is to develop novel methodologies to investigate membrane protein aggregation. Aggregation or non-specific association of membrane proteins is highly disadvantageous for further studies, including crystallization. Aggregation is also a problem for the production and long-term storage of biopharmaceuticals, an increasingly common form of therapeutic. My group have joined forces with Prof Sergei Kazarian of the Department of Chemical Engineering to investigate the use of ATR-FTIR chemical imaging as a tool for studying aggregation of both biopharmaceuticals and membrane proteins.
A long-standing collaboration with the Department of Science and Technology Laboratories (DSTL) on the pathogenic bacterium Yersinia pestis aims to identify and characterise novel vaccine targets and understand mechanisms of host immune system evasion through structural and functional studies of key bacterial proteins.This research has expanded to allow study of proteins involved in negative regulation of the innate immune response both as part of the normal homeostasis and as a mechanism of pathogen evasion of the host immune response in collaboration with Prof Ding Jeak Ling, National University of Singapore.
The research activities of the laboratory are/have been funded by BBSRC, MRC, GlaxoSmithKline, DSTL and EU FP7.
- EMBO workshop, Marseilles, July 11.
- Crystallisation and Crystallography of Membrane Proteins, DLS, June 09.
- Crystallisation and Crystallography of Membrane Proteins, Diamond Light Source, April 08 (also organiser).
- Membrane proteins, Leeds, March 2007.
- Handling membrane proteins, Goteborg, May 2006 (also organiser).
et al., 2017, Butane-1,2,3,4-tetraol-based amphiphilic stereoisomers for membrane protein study: importance of chirality in the linker region, Chemical Science, Vol:8, ISSN:2041-6520, Pages:1169-1177
et al., 2017, Conformationally Preorganized Diastereomeric Norbornane-Based Maltosides for Membrane Protein Study: Implications of Detergent Kink for Micellar Properties, Journal of the American Chemical Society, Vol:139, ISSN:0002-7863, Pages:3072-3081
et al., 2017, Resorcinarene-Based Facial Glycosides: Implication of Detergent Flexibility on Membrane-Protein Stability, Chemistry-a European Journal, Vol:23, ISSN:0947-6539, Pages:6724-6729
et al., 2016, Structure of eukaryotic purine/H+ symporter UapA suggests a role for homodimerization in transport activity, Nature Communications, Vol:7, ISSN:2041-1723
et al., 2016, Transporter oligomerization: form and function, Biochemical Society Transactions, Vol:44, ISSN:0300-5127, Pages:1737-1744