Asymmetric phosphoinositide lipid bilayers generated by spontaneous lipid insertion.

Area of Science:

• Biochemistry
• Cell Biology
• Materials Science

Background:

• Phosphatidylinositol phosphate (PIP) lipids are vital regulators of cellular processes, particularly actin assembly.
• Supported lipid bilayers (SLBs) are used to model PIP lipid-protein interactions.
• Creating fluid, asymmetric SLBs with mobile PIP lipids remains a challenge.

Purpose of the Study:

• To develop a simple and robust method for generating asymmetric SLBs containing tunable amounts of PI(4,5)P2.
• To confirm the mobility and functionality of incorporated PI(4,5)P2.
• To provide a versatile strategy for creating asymmetric lipid bilayers.

Main Methods:

• Dissolving PI(4,5)P2 below its critical micelle concentration (CMC) for spontaneous insertion into SLBs.
• Utilizing fluorescence recovery after photobleaching (FRAP) to assess PI(4,5)P2 mobility.
• Recruiting actin-binding proteins like ezrin and myosin 1 to the functionalized SLBs.

Main Results:

• A straightforward method was established to generate asymmetric SLBs with controllable PI(4,5)P2 levels.
• PI(4,5)P2 demonstrated mobility within the SLB upper leaflet.
• Incorporated PI(4,5)P2 successfully recruited binding partners and mediated actin filament sliding.

Conclusions:

• The developed method provides a robust way to create asymmetric PI(4,5)P2-containing SLBs.
• This approach facilitates the study of PIP lipid-protein interactions in a biomimetic system.
• The method is adaptable for incorporating other lipid species with high CMC values.