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

Journal article

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.

Authors: Honigmann, A; Sadeghi, S; Keller, J; Hell, S; Eggeling, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: eLife Sciences Publications
• Journal: eLife
• Volume: 2014
• Issue: 3
• Article number: e01671
• Publication date: 2014-03-18
• Acceptance date: 2014-02-14
• DOI: 10.7554/elife.01671
• EISSN: 2050-084X
• Language: English
• Keywords: fluorescence correlation spectroscopy; FFR; membrane organization; STED microscopy; cortical actin; pinning sites; lipid phase separation