The methodology of constant tension-induced
rupture of giant
unilamellar vesicles (GUVs) has provided information on tension-induced pore formation. This method was used to investigate the effect of spontaneous curvature (H0) for a
lipid monolayer on the rate constant (kr) for constant tension (σ)-induced
rupture, which originates from pore formation in
lipid bilayers.
Lipids were incorporated with different H0 values into GUV membranes to change the overall H0 value for the GUV monolayer. The dioleoylphosphatidylglycerol (
DOPG)/
dioleoylphosphatidylethanolamine (DOPE) (4/6, molar ratio, here and elsewhere) monolayer has a negative H0, whereas the
DOPG/
dioleoylphosphatidylcholine (
DOPC) (4/6) monolayer has an essentially zero H0. A higher tension was required to induce the
rupture of
DOPG/DOPE (4/6)-GUVs compared with
DOPG/
DOPC (4/6)-GUVs. The line tension (Γ) for a pre-pore in
DOPG/DOPE (4/6)-GUVs, determined by the analysis of the tension dependence of kr, was 1.5 times larger than that in
DOPG/
DOPC (4/6)-GUVs. The kr values for GUVs comprising
DOPG/
DOPC/18:1
lysophosphatidylcholine (LPC) (40/55/10), which has a positive H0, were larger than those for
DOPG/
DOPC (4/6)-GUVs under the same tension. The Γ value for
DOPG/
DOPC/LPC (40/55/10)-GUVs was almost half that for
DOPG/
DOPC (4/6)-GUVs. These results indicate that Γ decreases with increasing H0, which results in an increase in kr. Based on these results, the effect of H0 on kr and Γ is discussed.