A lipid bound actin meshwork organizes liquid phase separation in model membranes

The eukaryotic cell membrane is connected to a dense actin rich cortex. We present FCS and STED experiments showing that dense membrane bound actin networks have severe influence on lipid phase separation. A minimal actin cortex was bound to a supported lipid bilayer via biotinylated lipid streptavi...

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Bibliographic Details
Published in:eLife 2014-03, Vol.3, p.e01671-e01671
Main Authors: Honigmann, Alf, Sadeghi, Sina, Keller, Jan, Hell, Stefan W, Eggeling, Christian, Vink, Richard
Format: Article
Language:English
Subjects:
Actin
Actins - metabolism
Biophysics and Structural Biology
Cholesterol
Computer Simulation
cortical actin
fluorescence correlation spectroscopy
Hypotheses
Lipid Metabolism
lipid phase separation
Lipids
Membrane composition
membrane organization
Membranes
Membranes - chemistry
Membranes - metabolism
Microscopy
Microscopy, Fluorescence
Models, Theoretical
Phase transitions
Physiology
pinning site
Plasma
Protein Binding
Proteins
STED microscopy
Streptavidin
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Summary:The eukaryotic cell membrane is connected to a dense actin rich cortex. We present FCS and STED experiments showing that dense membrane bound actin networks have severe influence on lipid phase separation. A minimal actin cortex was bound to a supported lipid bilayer via biotinylated lipid streptavidin complexes (pinning sites). In general, actin binding to ternary membranes prevented macroscopic liquid-ordered and liquid-disordered domain formation, even at low temperature. Instead, depending on the type of pinning lipid, an actin correlated multi-domain pattern was observed. FCS measurements revealed hindered diffusion of lipids in the presence of an actin network. To explain our experimental findings, a new simulation model is proposed, in which the membrane composition, the membrane curvature, and the actin pinning sites are all coupled. Our results reveal a mechanism how cells may prevent macroscopic demixing of their membrane components, while at the same time regulate the local membrane composition. DOI: http://dx.doi.org/10.7554/eLife.01671.001.
ISSN:2050-084X
2050-084X
DOI:10.7554/eLife.01671