Simulations of Myosin-Dependent Vesicle Clustering and Actin-Based Propulsion in Plant Cells

Vesicle trafficking is essential for plant cell growth, especially in tip-growing cells, where vesicles are directed to the expanding end of the cell through actin-myosin interactions. This study employs computer simulations to investigate vesicle dynamics in plant cells, specifically examining how myosin and actin filament attachment and polymerization influence vesicle diffusion, clustering, and transport. We utilized Cytosim, a cellular simulation program based on Langevin dynamics, to study vesicle transport by myosin and actin filaments. We analyzed single vesicle diffusion and vesicle-actin complexes with varying filament lengths and numbers. We found that vesicle diffusion decreased significantly with attached filaments, particularly between 200 nm and 2 μm in length. Multiple filaments further reduced diffusion, with their effects being more pronounced than increases in single filament length. When the filaments were simulated as active by allowing polymerization and depolymerization, the vesicle showed super diffusive behavior, with highly directed transport by longer or more abundant filaments. These simulations suggest potentially novel forms for the regulation of vesicle transport in cells. Additionally, simulations of myosin XI-dependent vesicle clustering replicated in vivo observations, supporting a model in which myosin XI, formins, and F-actin play crucial roles in vesicle clustering and directed movement in tip-growing plant cells. These findings provide insights into the mechanisms of vesicle transport and clustering, highlighting the role of myosin and actin dynamics in cellular processes involving vesicle trafficking in plants.