Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Abstract Tracking membrane‐interacting molecules and visualizing their conformational dynamics are key to understanding their functions. It is, however, challenging to accurately probe the positions of a molecule relative to a membrane. Herein, a single‐molecule method, termed LipoFRET, is reported to assess interplay between molecules and liposomes. It takes advantage of FRET between a single fluorophore attached to a biomolecule and many quenchers in a liposome. This method was used to characterize interactions between α‐synuclein (α‐syn) and membranes. These results revealed that the N‐terminus of α‐syn inserts into the membrane and spontaneously transitions between different depths. In contrast, the C‐terminal tail of α‐syn is regulated by calcium ions and floats in solution in two conformations. LipoFRET is a powerful tool to investigate membrane‐interacting biomolecules with sub‐nanometer precision at the single‐molecule level.