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Electrostatics of lipid bilayer bending
T Chou1, M V Jarić, E D Siggia
1Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA. siggia@msc.cornell.edu
Biophysical Journal
|May 1, 1997
Summary
Electrically charged surfaces on cell membranes can induce spontaneous curvature, influencing organelle shape and budding. This electrostatic bending mechanism is crucial for cellular processes, even without intrinsically curved proteins.
Area of Science:
- Biophysics
- Cell Biology
- Physical Chemistry
Background:
- Spontaneous membrane curvature is vital for cellular functions like vesicle formation.
- The role of electrostatic forces in inducing membrane curvature is not fully understood.
- Existing models often simplify charge distribution and screening effects.
Purpose of the Study:
- To calculate the electrostatic contribution to spontaneous membrane curvature using Poisson-Boltzmann theory.
- To investigate how asymmetrical surface charges and unequal screening layers affect membrane bending.
- To explore the impact of charge conservation within vesicles on membrane curvature.
Main Methods:
- Poisson-Boltzmann theory was applied to model electrostatic interactions.
- Calculations were performed considering various assumptions and physiological parameters.
- The study analyzed charge fixation relative to bilayer midplane and lipid-water areas.
- Effects of different ionic environments (e.g., multivalent cations, monovalent salts) were simulated.
Main Results:
- Asymmetrical surface charges induce membrane curvature of opposite signs depending on fixation.
- Unequal screening layers, such as proteins versus salt, also lead to membrane bending.
- Electrostatically induced tubules can exhibit radii of 50-100 nm, consistent with organelle dimensions.
- The electrostatic bending modulus is generally small, suggesting it's an adjustable parameter.
Conclusions:
- Membrane-associated proteins can induce curvature and budding via electrostatic interactions.
- This mechanism provides a way to form curved membrane structures without intrinsically curved proteins.
- Charge conservation within vesicles influences electrostatic curvature, a previously unexplored effect.
- The findings offer insights into organelle morphology and membrane dynamics.