Mutual Dependence between Membrane Phase Separation and Bacterial Division Protein Dynamics in Synthetic Cell Models

Area of Science:

• Bacterial cell division
• Membrane biophysics
• Biochemistry

Background:

• Bacterial cell membranes exhibit lateral polarization, creating specialized microenvironments for proteins like those in cell division.
• Membrane lipid domains and proteins dynamically reorganize during cell division, suggesting functional roles for membrane compartmentalization.

Purpose of the Study:

• To investigate the interplay between protein pattern formation and membrane heterogeneity using an in vitro model.
• To explore the role of lipid domains in bacterial division protein localization and function.

Main Methods:

• Utilized a vesicle-based in vitro model with phase-separated giant unilamellar vesicles (GUVs).
• Incorporated archetypal bacterial division proteins (MinC, MinD, MinE, FtsA, FtsZ) into the GUV system.
• Observed protein binding, pattern formation, and membrane deformation using microscopy.

Main Results:

• Min proteins preferentially bind to and form patterns at liquid-disordered (Ld) domains within GUVs.
• Phase-separated GUVs with division proteins exhibited blebbing-like deformations.
• Liquid-ordered (Lo) domains reorganized to align at the bleb neck, mimicking bacterial cell division events.

Conclusions:

• The in vitro model demonstrates a mutual dependence between protein pattern formation and membrane heterogeneity in bacterial division.
• Lipid domain organization plays a crucial role in bacterial cell division mechanics and spatial patterning.
• This framework aids in understanding bacterial division within complex cellular lipid environments.