The Two Faces of the Liquid Ordered Phase

0554270 - ÚOCHB 2023 RIV US eng J - Journal Article
Schachter, Itay - Paananen, R. O. - Fábián, Balázs - Jurkiewicz, Piotr - Javanainen, Matti
The Two Faces of the Liquid Ordered Phase.
Journal of Physical Chemistry Letters. Roč. 13, č. 5 (2022), s. 1307-1313. ISSN 1948-7185
R&D Projects: GA ČR(CZ) GX19-26854X
Institutional support: RVO:61388963 ; RVO:61388955
Keywords : gel phase * phospholipid bilayers * molecular motion
OECD category: Physical chemistry; Physical chemistry (UFCH-W)
Impact factor: 5.7, year: 2022
Method of publishing: Open access
https://doi.org/10.1021/acs.jpclett.1c03712

Coexisting liquid ordered (Lo) and liquid disordered (Ld) lipid phases in synthetic and plasma membrane-derived vesicles are commonly used to model the heterogeneity of biological membranes, including their putative ordered rafts. However, raft-associated proteins exclusively partition to the Ld and not the Lo phase in these model systems. We believe that the difference stems from the different microscopic structures of the lipid rafts at physiological temperature and the Lo phase studied at room temperature. To probe this structural diversity across temperatures, we performed atomistic molecular dynamics simulations, differential scanning calorimetry, and fluorescence spectroscopy on Lo phase membranes. Our results suggest that raft-associated proteins are excluded from the Lo phase at room temperature due to the presence of a stiff, hexagonally packed lipid structure. This structure melts upon heating, which could lead to the preferential solvation of proteins by order-preferring lipids. This structural transition is manifested as a subtle crossover in membrane properties, yet, both temperature regimes still fulfill the definition of the Lo phase. We postulate that in the compositionally complex plasma membrane and in vesicles derived therefrom, both molecular structures can be present depending on the local lipid composition. These structural differences must be taken into account when using synthetic or plasma membrane-derived vesicles as a model for cellular membrane heterogeneity below the physiological temperature.
Permanent Link: http://hdl.handle.net/11104/0328903


Research data: Zenodo, Zenodo