Propagation of MinCDE waves on free-standing membranes

Area of Science:

• Cell biology
• Biophysics
• Biochemistry

Background:

• The Min system in Escherichia coli spatially regulates cell division by forming waves on the cell membrane.
• This mechanism, driven by ATP hydrolysis, ensures cytokinesis occurs only at the cell center.
• Previous in vitro studies on supported lipid bilayers (SLBs) reproduced Min protein dynamics but showed discrepancies in wave propagation speed.

Purpose of the Study:

• To investigate the impact of membrane fluidity and protein diffusion on Min protein wave propagation.
• To quantitatively compare Min wave dynamics on supported lipid bilayers (SLBs) versus fluid giant unilamellar vesicles (GUVs).

Main Methods:

• Reconstruction of Min protein reaction-diffusion system in vitro.
• Comparison of Min wave propagation on supported lipid bilayers (SLBs) and fluid giant unilamellar vesicles (GUVs).
• Analysis of wave velocity, wavelength, and period on different membrane models.

Main Results:

• Min protein waves on more fluid GUVs exhibited three times higher propagation velocity and wavelength compared to SLBs.
• The wave period remained consistent across both membrane types (SLBs and GUVs).
• This indicates that membrane diffusion significantly influences Min wave characteristics.

Conclusions:

• Lower protein diffusion on bacterial inner membranes likely explains the slower Min wave propagation observed in vivo compared to in vitro models.
• Membrane fluidity is a critical factor in determining the spatial patterns of the Min system.
• Findings provide insights into the regulation of bacterial cytokinesis and the role of membrane properties.