Flip Flop-Associated Growth and Division of Synthetic Cells

Area of Science:

• Cell biology
• Biophysics
• Synthetic biology

Background:

• Cellular growth necessitates membrane expansion through lipid synthesis and vesicle fusion.
• Lipid redistribution across the bilayer is essential for maintaining membrane homeostasis during cell growth.
• Transmembrane lipid imbalance can lead to membrane stress and affect cellular processes.

Purpose of the Study:

• To investigate the role of lipid flip-flop in membrane dynamics during cellular growth and division.
• To quantify the morphological changes in growing synthetic cells under varying lipid flip-flop conditions.
• To understand the mechanisms of curvature stress relief and bud scission in lipid bilayers.

Main Methods:

• Utilized giant unilamellar vesicles (GUVs) and large unilamellar vesicles (LUVs) to model cellular growth.
• Recapitulated cellular growth and division by fusing LUVs to GUVs under controlled conditions.
• Dynamically monitored GUV volume, spontaneous curvature, and area difference to quantify morphology.

Main Results:

• Demonstrated that membranes with flip-flop-capable lipids relieve curvature stresses during growth.
• Observed the generation of more symmetrically sized buds without compromising membrane integrity.
• Showed that increased neck curvature promotes bud scission, leading to division.

Conclusions:

• Lipid flip-flop is a key mechanism for relieving membrane curvature stresses during cellular growth.
• The presented mechanisms provide insights into the growth and division of early protocells.
• This research contributes to the design of synthetic cells capable of growth and division.