UC Riverside

Cellular budding is an important biological process utilized by cells to survive and reproduce. It is characterized by the local protrusion on a cell surface that proceeds to form a vesicle separated from the original cell. The underlying mechanisms of cellular budding vary according to different cell types but can be generally categorized into the non-growth related and growth related process. For non-growth related budding, the process is often driven by the adhesive interaction between nanoparticle, surface-bound proteins, or actin filaments and the cell membrane at the nanometer scale. For growth related budding, similar contributors in the non-growth related budding may be present but the budding process at this scale requires recruitment of new cell surface materials. Novel tunable and biologically relevant 3D mathematical model is developed for studying the budding of yeast (Saccharomyces cerevisiae). The model incorporates growth of the cell via expansion of the cell surface and it is used to investigate the role of changes in mechanical properties

on bud emergence and bud shape maintenance. Model simulations suggest that changes in the mechanical properties of the cell surface are necessary for yeast budding, and the resulting quality of the shape of the bud depends on the types and patterns of changes. The 3D model is also applied, with modifications, to study the process of endocytosis and virus budding in the context of nanoparticle-membrane interactions. This model is capable of representing the fluidic property of the cell membrane that allows reorganization of membrane components leading to various geometrical shapes. Model computational simulations have demonstrated the impact of different levels of membrane fluidity on the efficiency and surface coverage in the wrapping of a nanoparticle by the membrane. In particular, higher level of membrane fluidity was shown to lead to efficient wrapping of the nanoparticle.