Asymmetric distribution of lipids and peptides induces asymmetric lipid packing and membrane tension

What is it about?

It is well known that the area difference in both monolayer due to asymmetric distribution of lipids induces various shape changes of nonspherical vesicles such as giant unilamellar vesicles (GUVs). However, there is no information on the effects of the asymmetric distribution of lipids and peptides in two monolayers of spherical vesicles (i.e., nonequal number of lipids and peptides in both leaflets), but these effects are important for various researches using spherical GUVs. In this paper, we tackled these problems theoretically.

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Why is it important?

By calculating the minimum of free energy of the lipid bilayers with the transmembrane asymmetric distribution of lipids, we obtained the theoretical values of the fractional area change in both monolayers as a function of asymmetry, which agree with those obtained by MD simulations. This result indicates that asymmetric packing of lipids in both monolayers is produced (i.e., one monolayer is stretching and the other is compressed). We obtained the membrane tensions in both leaflets theoretically, and found that they have opposite directions but the same magnitude. Next, we examined the effect of asymmetric distribution of peptides which bind in the membrane interface. We obtained the theoretical equation of the fractional area change, indicating the asymmetric lipid packing and the asymmetric membrane tension in both monolayers.