Optimized filopodia formation requires myosin tail domain cooperation

Significance

Cells interact with their environment using filopodia, thin membrane protrusions supported by actin filaments. Filopodia formation in evolutionarily divergent organisms requires force generation by a MyTH4-FERM (MF) myosin that binds membrane proteins and is designed to promote cytoskeletal reorganization and filopodial transport. The amoeboid filopodial MF myosin is found to be a resilient motor in filopodia formation. Its activity and regulation appear to have emerged by multidomain coevolution for optimized control of filopodia formation and stability. Its properties reflect those of the ancestral MF myosin that gave rise to the metazoan MF myosins. These findings have implications for understanding the fundamental principles of how filopodia form and how MF myosins function in phylogenetically distant organisms.