Curved membrane structures induced by native lipids in giant vesicles.

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Native lipids in cell membranes are crucial for functions like cell communication.
• Understanding lipid roles in membrane transformation requires accurate cell membrane models.
• Giant unilamellar vesicles (GUV) are essential but challenging to assemble for mimicking native membranes.

Purpose of the Study:

• To construct and analyze giant vesicle models of bacterial inner and outer membranes.
• To investigate the membrane deformation and shape dynamics of these models under physiological conditions.
• To quantitatively describe membrane structures and determine elastic parameters.

Main Methods:

• Single-step gel-assisted lipid swelling technique to form GUVs.
• Construction of two vesicle models: bacterial inner membrane (IM) and outer membrane (OM).
• Analysis of membrane remodeling and deformation under controlled osmotic stress.

Main Results:

• IM vesicles showed small-scale remodeling into buds and short nanotubes.
• OM vesicles, containing lipopolysaccharide (LPS), exhibited global membrane deformation.
• OM vesicles formed complex, highly-curved structures like daughter vesicle networks and nanotubes at comparable osmotic stress to IM vesicles.
• Experimentally determined membrane elastic parameters (neck curvature, bending rigidity) revealed differences between IM and OM vesicles.

Conclusions:

• OM vesicles deform more significantly than IM vesicles due to larger spontaneous curvature and softer membranes.
• These findings provide insights into the shape dynamics of complex native bacterial lipid membranes.
• The study offers a method to generate biomimetic membrane structures for further research.