Variation of lipid membrane composition caused by strong bending |
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Authors: | P V Bashkirov K V Chekashkina S A Akimov P I Kuzmin V A Frolov |
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Institution: | 1.Frumkin Institute of Physical Chemistry and Electrochemistry,Russian Academy of Sciences,Moscow,Russia;2.The Federal State Educational Institution of the Higher Professional Education National University of Science and Technology “MISIS”,Moscow,Russia;3.Unidad de Biofisica (Centro Mixto CSIC-UPV/EHU),Leioa,Spain;4.Departamento de Biochimica y Biologia Molecular,Universidad del Pais Vasco,Leioa,Spain;5.Basque Foundation for Science,IKERBASQUE,Bilbao,Spain |
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Abstract: | Dynamic coupling between the morphology and molecular composition of cellular membranes is crucial for formation of the intracellular
organelles and transport vesicles. Most of the membrane proteins and lipids discriminate membrane curvatures. However, it
remains unclear whether the curvature alone is sufficient to support heterogeneous distribution of lipids. Here we demonstrate
that the curvature-driven redistribution of phospholipids, such as dioleoylphosphatidylethanolamine (DOPE), requires strong
membrane bending. We used cylindrical lipid nanotubes (NTs) pulled from planar lipid membranes with lateral tension of ∼1
dyn/cm. Such high tensions forced extreme curvatures of the NT membrane, with luminal radius approaching the thickness of
the lipid bilayer, 5nm. When the NT contained lipid species with high spontaneous curvature (SC), such as DOPE, we observed
slow reduction of its radius. This reduction indicated the redistribution of DOPE between the inner and outer monolayers of
the NT. Accordingly, the SC of DOPE was recovered from the measured changes in the radii: the SC value, calculated under the
assumption that the DOPE content is coupled to the monolayer curvature, was ∼0.4 nm−1, consistent with the published data. Thus, redistribution of lipids should be taken into account in calculations of composition
and material properties of strongly deformed membrane structures, such as intermediate structures arising in the processes
of membrane fusion and fission. |
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