Dynamin Action at the Final Stage of Clathrin-Mediated Endocytosis

Abstract

Dynamin plays an important role in clathrin-mediated endocytosis by cutting the neck of nascent vesicles from the cell membrane. Gold nanorods were used as imaging probes to observe dynamin action on cargo vesicles during live endocytosis events. Invariant is that at the peak of dynamin accumulation, the cargo-containing vesicle always gives abrupt, right-handed rotations that finishes in a short time (~ 0.28 s). The large and quick twist, herein named the super twist, is the result of the coordinated dynamin helix action upon GTP hydrolysis. After the super twist, the rotational freedom of the vesicle drastically increases, accompanied with simultaneous or delayed translational movement, indicating that it detaches from the cell membrane. These observations suggest that dynamin-mediated scission at the final stage involves a large torque generated by coordinated actions of multiple dynamins in the helix, which is the main driving force for scission. The super twist presumably results in membrane tube hemi-fission and partial destruction of the dynamin helix, followed by vesicle fission.