Most recent information on work in the group can be found on our website.
My group is interested in understanding the assembly and function of membrane-proteins using techniques that are capable of observing individual molecules.
In general, our understanding of biomolecules is derived from experiments where the average properties of a population are measured. By using techniques capable of resolving single molecules it is possible to see more than just these ensemble-averaged attributes. For example, we can measure the distribution of a particular molecular property, or the reaction pathway followed by an individual molecule. The complexity of biological molecules, in both their underlying dynamic structure and their interactions, makes this single-molecule approach particularly valuable.
We are interested in using these single-molecule methods to help us how membrane protein complexes form, the role of the lipid membrane in affecting the behaviour of membrane proteins, and how small chemical liganads can influence the conformation of membrane-bound receptors.
Our principal tools are single-molecule laser microscopy and single-channel electrical recording. We use molecular biology to engineer proteins with fluorescent markers. These labelled proteins are then interrogated under the microscope. We collect data from many tens of thousands of molecules, and interpreting this data often requires the development of new computational tools and models.
Assembly of pore-forming proteins
In collaboration with Hagan Bayley we are studying the mechanism of pore-protein assembly. Pore-forming bacterial toxins such as Staphylococcal a-hemolysin (a-HL) provide an excellent model for studying the oligomerisation of membrane proteins, due to the high stability and solubility of the monomeric subunits. The bulk behaviour of a-HL has been characterised in detail; with known crystal structure, and extensive investigation of the electrical properties of the pore. The current working model for pore assembly involves two intermediates. We are currently testing this model of pore assembly by studying the interactions of single fluorescently labelled a-HL monomers.
Ligand binding and gating in ion-channels
Using simultaneous single-molecule fluorescence and single-channel electrical recording we are studying the mechanism by which ion channel gating is regulated by ligand binding. The gating of ion channels in response to the binding of chemical ligands is a critical step in many signal transduction pathways. Working with Stephen Tucker, we are interested in understanding the relationship between binding, transduction and gating at the single-molecule level.
New single-molecule methods
Our group is also developing new methods to image and manipulate lipid bilayers and membrane proteins.