Building on my earliest observations of ligand binding to folded proteins, I became fascinated by the balance of interactions that enable proteins and their complexes to survive in the gas phase. This has guided my research over the years and prompted many of my current questions and future directions.
The central tenet of our research is that native mass spectrometry (MS), a technique which enables interactions of proteins to be maintained in the gas phase, can provide unparalleled information on the structure, binding partners and dynamics of proteins, complementing other biophysical approaches yet a powerful tool in its own right. Particularly exciting is, I believe, the agility with which native MS can be adapted and applied to the research challenges of our time. Our overall goal is to continue to develop and advance our native MS methods for application to a range of fundamental and applied research goals. Current projects are given below:
Recapitulating physiological environments using novel detergents and membrane mimetics
Manipulating the chemical properties of detergents is allowing us to fine-tune lipid binding and extraction conditions for membrane proteins. Similarly, the use of membrane mimetics, such as lipodisqs (or SMALPs), enables us to capture lipid interactions from native-like environments while nanoemitters are facilitating the study of receptors in high concentrations of physiological relevant metal ions.
Ejecting complexes directly from membranes
Extraction from native membranes can sometimes change the structure and lipid binding properties of protein complexes leading to conflicting results and fuelling a drive to study complexes directly from native membranes. We are developing approaches whereby complexes can be ejected directly from membranes to inform on their lipid binding partners and response to challenge with antibiotics or other drug molecules.
Uncovering mechanisms of drug resistance
The effects of lipid binding on the conformation and stoichiometry of membrane proteins is particularly important for complexes involved in antimicrobial resistance mechanisms. Binding of cell wall lipid components, as well as monitoring lipid flipping and antibiotic binding, is leading to an increase in our understanding of the roles of lipids and other small molecules in these critical mechanisms.
Linking post-translational modifications to function of protein complexes
Incorporation of different isoforms and protein lipid binding properties, particularly of solute carriers, GPCRs and rotary ATPases, is informing many aspects of the structural biology of these complexes. Studying these complexes from different cellular environments, for example kidney and brain, as well as applying new methods of activation and detection, is further contributing to our understanding of their structure- function relationships.
Trapping metabolites in membrane proteins to link protein complexes to health disorders
Ligands within protein assemblies provide critical information for function yet are often difficult to capture and define. We have developed a novel top-down method, “Nativeomics”, unifying “omics” (lipidomics, proteomics, metabolomics) with native mass spectrometry to identify ligands bound to membrane protein assemblies. By maintaining the link between proteins and ligands we are able to define the lipidome/metabolome in contact with membrane proteins and thereby discover potential regulators of protein function.