SKM 2021 – wissenschaftliches Programm
CPP 6.11: Poster
Dienstag, 28. September 2021, 17:30–19:30, P
Measuring the line tension of a hemifusion diaphragm — •Yu-Jung Su, Yuliya Smirnova, and Marcus Müller — Institut für Theoretische Physik, Georg-August-Universität, 37077 Göttingen, Deutschland
Changes of membrane topology are essential to cellular transport processes, such as e.g., synaptic release. The molecular pathways, however, are only incompletely understood. The hemifusion diaphragm (HD) is a putative intermediate, where two apposing membranes are locally fused into a single-membrane patch. The line tension of the three-bilayer junction at the rim of the HD controls the size and stability of the HD, and it is an important parameter for phenomenological free-energy models of fusion and fission processes. In the canonical ensemble, where the number of lipids is fixed, the line tension, λ, of the HD, which tends to decrease the area of the HD, is balanced by the membrane tension, π, resulting in a two-dimensional analog of the Laplace equation between λ, π, and the radius, R, of the HD. Using molecular dynamics simulation of the coarse-grained MARTINI model, we study this free-energy balance and calculate the line tension as a function of the membrane tension or the distance between the flat membranes in apposition. The results are compared to alternate estimates, e.g., obtained from the shape fluctuations of the rim of the HD.