Most drug targets are the transmembrane receptor proteins that regulate cellular processes via conformational signaling. We identify the underlying conformational states and dynamics with single-molecule FRET.
Tar, a sugar receptor from E. coli, embedded in a nanodisc (left) exhibits conformational changes upon binding of the sugar aspartate (insert). Using smFRET, the distances between helix pairs can be measured (right).
Bacterial chemotaxis. Chemotaxis is the mechanism by which bacteria sense and respond to chemical gradients within the environment, including identifying favorable locations for infection. In the initial steps of chemotaxis, transmembrane chemoreceptors bind ligands in the periplasmic domain to regulate a kinase bound to their cytoplasmic tails. We combine biochemical and spectroscopic techniques to monitor the conformational signaling by which ligand binding is communicated to the cytoplasmic domain.
Epidermal growth factor receptor. The epidermal growth factor receptor (EGFR) maintains major cellular functions, including cell division, and its aberrant expression leads to multiple disorders, including cancer. The extracellular domain of EGFR binds ligands, which drives oligomerization and phosphorphorylation of tyrosines in the intraclelular domain. We use smFRET to identify the conformational changes along the structure of EGFR.
Fluorescently-labeled EGFR immobilized on Ni-NTA coverslip