MPP1 controls lipid domain remodelling in giant vesicles containing reconstituted flotillins

Membrane palmitoylated protein 1 (MPP1), a protein found to directly interact with flotillins, has been shown to play a crucial role as a raft-capturing molecule, modulating dynamics of flotillin-nanodomains and affects plasma membrane (PM) organisation in native erythroid cells. This study aims to reconstitute the flotillin-MPP1 complexes in a minimal membrane-based system to check its ability to govern domain formation and modulate fluidity and phase separation of membranes comprising simple ternary lipid mixtures. Using recombinant flotillins reconstituted into giant unilamellar vesicles (GUVs) and fluorescence lifetime imaging (FLIM), we have shown that MPP1 promotes membrane remodelling and triggers the coexistence of liquid-ordered (L_o) and liquid-disordered (L_d) domains. Additionally, we examined whether palmitoylation of MPP1 affects lipid bilayers and demonstrated that it exerts a certain influence on membrane organisation. Our data highlights that flotillin-MPP1 assemblies are sufficient and necessary to modulate the lateral organisation of lipid bilayers, pointing to their crucial role in PM organisation. Additionally, we propose a new toolset for successful flotillin reconstitution in GUVs, which is a viable platform compatible with a wide spectrum of flotillin-based studies on model membrane systems.