Effect of monolayer spontaneous curvature on constant tension-induced pore formation in lipid bilayers

What is it about?

The experimental methodology of constant tension-induced rupture of a giant unilamellar vesicle (GUV) has provided the rate constant (k) of constant tension-induced pore formation and the line tension of the rim of a prepore which is produced before pore formation. Here, we examined the effect of monolayer spontaneous curvature (H0) on the constant tension-induced pore formation in the GUV membrane.

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Why is it important?

Monolayers of dioleoylphosphatidylethanolamine (DOPE) and those of the mixture of DOPE and DOPG have negative H0 values, whereas the monolayers of DOPC and DOPG have essentially zero H0 values. We prepared the DOPG/DOPE (4/6)-GUVs and DOPG/DOPC (4/6) -GUVs in a buffer containing a physiological concentration of ions. The k values of DOPG/DOPE (4/6)-GUVs were smaller than those of DOPG/DOPC (4/6)-GUVs at the same tensions. The line tension of the rim of a prepore in DOPG/DOPC-GUVs was larger than that in DOPG/DOPC-GUVs. On the other hand, DOPG/DOPC/lysoPC (40/55/10) has a positive H0. The k values of DOPG/DOPC/lysoPC-GUVs were larger than those of DOPG/DOPC-GUVs at the same tensions, and the line tension of the rim of a prepore in DOPG/DOPC/lysoPC-GUVs was smaller than that in DOPG/DOPC-GUVs. These results indicate that the line tension decreases with an increase in the monolayer spontaneous curvature (H0), resulting in an increase in the rate constant (k) of constant tension-induced pore formation.