Unbinding-binding transition induced by molecular snaps in model membranes

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Biophysics

Background:

• Model membranes, specifically lamellar phases of nonionic surfactants, dodecane, and water, are crucial for studying membrane interactions.
• The interlamellar distance in these systems typically depends on the membrane volume fraction (Phi).

Purpose of the Study:

• To investigate the effect of macromolecular inclusions acting as membrane binders (macromolecular snaps) on lamellar phase structure.
• To determine how the length and concentration of these inclusions influence interlamellar spacing and membrane interactions.

Main Methods:

• Utilizing a lamellar phase model system composed of a nonionic surfactant, dodecane, and water.
• Introducing transmembrane proteins and de novo designed peptides of varying lengths and compositions as macromolecular inclusions.
• Analyzing changes in interlamellar distance and fitting experimental data to a thermally stabilized membrane model.

Main Results:

• Macromolecular inclusions induce a binding transition in the lamellar phase, altering interlamellar distance.
• The interlamellar distance becomes dependent on the surface concentration of snaps, not solely on the membrane volume fraction (Phi).
• Inclusions with hydrophobic segments require a length at least equal to the membrane's hydrophobic length to be effective; model parameters must account for inclusion length.

Conclusions:

• Macromolecular inclusions significantly modify the structural organization of lamellar phases by acting as membrane-bridging elements.
• The effectiveness of these inclusions is dictated by their specific characteristics, including length and hydrophobic interactions.
• A refined model incorporating inclusion length is necessary for accurately predicting membrane interactions in the presence of such components.