Regulating Lipid Composition Rationalizes Acyl Tail Saturation Homeostasis in Ectotherms

Area of Science:

• Biochemistry
• Computational Biology
• Membrane Biophysics

Background:

• Cell membranes feature actively regulated lipid bilayers with hundreds of components.
• The mechanisms controlling lipid composition and the correlation between cholesterol and phospholipid saturation are poorly understood.

Purpose of the Study:

• To investigate the link between cell membrane regulation and chemical composition.
• To develop a computational model explaining how lipid composition is controlled.

Main Methods:

• Established a computational framework using chemical reaction networks.
• Utilized multiple semigrand canonical ensembles for computer simulations.
• Modeled the regulation of lipid species' chemical potential.

Main Results:

• Demonstrated that regulating lipid chemical potential reproduces the observed increase in acyl tail saturation with cholesterol.
• Proposed a model where phospholipid acyl tail composition passively adapts to molecules like cholesterol and proteins.
• Observed that regulated membranes differ significantly from ternary model membranes, with correlations and viscosities independent of lipid chemical affinity.

Conclusions:

• Passive regulation of lipid composition is a viable mechanism for cell membranes.
• The chemical potential of lipid species plays a crucial role in membrane composition.
• Computational modeling provides insights into complex membrane dynamics and regulation.