Investigation on the relationship between lipid composition and structure in model membranes composed of extracted natural phospholipids

[Hypothesis] Unravelling the structural diversity of cellular membranes is a paramount challenge in life sciences. In particular, lipid composition affects the membrane collective behaviour, and its interactions with other biological molecules.
[Experiments] Here, the relationship between membrane composition and resultant structural features was investigated by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry on in vitro membrane models of the mammalian plasma and endoplasmic-reticulum-Golgi intermediate compartment membranes in the form of Langmuir monolayers. Natural extracted yeast lipids were used because, unlike synthetic lipids, the acyl chain saturation pattern of yeast and mammalian lipids are similar.
[Findings] The structure of the model membranes, orthogonal to the plane of the membrane, as well as their lateral packing, were found to depend strongly on their specific composition, with cholesterol having a major influence on the in-plane morphology, yielding a coexistence of liquid-order and liquid-disorder phases.
The authors thank the Institut Laue-Langevin (DOI: 10.5291/ILL-DATA.DIR-215) for financial support and allocation of beamtime, the ILL D-Lab for provision of the hydrogenous and deuterated yeast cells and the Partnership for Soft Condensed Matter (PSCM) for the lab support and provision of lipid extracts (L-Lab). Part of the lipid extraction activity was funded by the ANR/NSF-PIRE project REACT (Research and Education in Active Coatings Technologies for Human Health) and the Ligue for Advanced Neutron Sources (LENS). E.G. and A.M. received financial support from MICINN (grants PID2019-106557GB-C21 and PID2021-129054NA-I00, respectively), N.R.Z. from the Wellcome Trust (grant 207455/Z/17/Z). A. M. also acknowledges the financial support received from the IKUR Strategy under the collaboration agreement between Ikerbasque Foundation and Materials Physics Center on behalf of the Department of Education of the Basque Government. The National Deuteration Facility in Australia is partly funded by The National Collaborative Research Infrastructure Strategy (NCRIS), an Australian Government initiative.