The Molecular Mechanism of Monolayer Scission

Abstract

Hydrophobic globules surrounded by lipid monolayers are ubiquitous structures found in most cells, prokaryotic and eukaryotic. These structures, called lipid droplets, are hypothesized to accumulate as inclusions of oil-like molecules between the two leaflets of a membrane which grow larger and eventually bud off. The budding process is submicroscopic and difficult to observe in experiments, and studying it in molecular simulations has thus far presented computational challenges. Using dissipative particle dynamics, we attempt to understand the molecular details of the droplet budding process. We develop a lipid reservoir that can supply lipids to the bulging monolayer as the droplet buds out of the membrane. Our simulations support existing schematic models for the growth and budding process and predict a morphological transition between a partially and completely enveloped intermediate structure. Our results suggest a molecular mechanism for monolayer scission. Droplets generated using this technique can be useful in further studying the structure and dynamics of the droplet and its unique monolayer-integrated proteome.