Site-resolved dynamics of human membrane proteins
Far from switching between simple on and off states, GPCRs occupy a complex mixture of structural states in solution and sample between them on a variety of different timescales. Ligand binding to receptors causes different populations of these states as well as different exchange rates between them. This has been well-detailed by both single-molecule FRET (smFRET) and double electron-electron resonance (DEER) techniques, both of which have focused on measuring the outward movement of the 6th transmembrane helix, the area in GPCRs with the largest amplitude structural change upon activation. While DEER and smFRET are 1) responsive only to relatively large conformational changes and 2) require site-specific labeling with bulky exogenous groups, solution nuclear magnetic resonance (NMR) avoids both issues while allowing for structural & dynamic information to be observed for any and all atoms in the protein that can be isotopically labeled. That being said, NMR is notoriously difficult and expensive, particularly for proteins that cannot be expressed natively in bacteria (like GPCRs). To that end, the lab will develop and implement methods to facilitate NMR measurements of GPCR conformational dynamics, and pursue such studies in a wide array of important drug targets with unique ligands and signaling behaviors.