BPS2026 – All-atom models of cytoplasmic versus exoplasmic nanometer asymmetric vesicles

Cells use cytoplasmic and exoplasmic vesicles as vehicles for transports and communications between organelles within cells, and between cells, respectively. Since the membrane of cells are asymmetric in terms of lipid compositions, these cytoplasmic and exoplasmic vesicles are very likely asymmetric. Experimental studies of these vesicles at nanometer sizes, however, have been elusive. Thanks to recent advances in lipidomics, all-atom models of asymmetric lipid membranes can be computationally built. This opens opportunities to characterize the physical properties of cytoplasmic and exoplasmic vesicles. We have successfully built and run microseconds of these two vesicles based on lipidomic data. We found that while a cytoplasmic vesicle of about 30+ nm in diameter solvated in water and 0.15M NaCl can easily be stabilized, the exoplasmic one, whose lipid composition is reversed of the cytoplasmic vesicle, may undergo larger scrambling dynamics before being stabilized. Models of these two vesicles may allow further investigations into how they help to communicate and transport cellular materials for various functions.