Dynamin-dependent vesicle twist at the final stage of clathrin-mediated endocytosis

Abstract

Dynamin plays an important role in clathrin-mediated endocytosis (CME) by cutting the neck of nascent vesicles from the cell membrane. Here through using gold nanorods as cargos to image dynamin action during live CME, we show that near the peak of dynamin accumulation, the cargo-containing vesicles always exhibit abrupt, right-handed rotations that finish 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 involves a large torque generated by coordinated actions of multiple dynamins in the helix, which is the main driving force for vesicle scission.

Branched actin networks are organized for asymmetric force production during clathrin-mediated endocytosis in mammalian cells

“…Asymmetric N-WASP recruitment activates actin nucleation mostly at one side of the clathrin coat, generating an asymmetric force that pulls the membrane into the cell with a similar action to a bottle cap opener. We speculate that this asymmetrical force contributes to asymmetric membrane deformation at endocytic sites observed by high-speed atomic force microscopy 38 and may act with dynamin 39 to twist the clathrin pit to promote scission at the neck. CME events with associated actin assembly have longer lifetimes, likely due to a delay between the end of coat expansion and progress toward vesicle scission, requiring adaptive recruitment of actin regulators followed by actin network assembly and membrane remodeling.…”

Mapping nanoscale forces and potentials in live cells with microsecond 3D single-particle tracking

“…In future studies, dark-field illumination can be employed to achieve an even higher signal-to-background ratio, leading to 3D-SMARTER for smaller particles and with better spatial precision. Anisotropic scattering probes, such as nanorods, can also be explored in 3D-SMARTER to study the rotational potentials on complex biological surfaces (26,(55)(56)(57), adding yet another dimension to this powerful method.…”

Centronuclear Myopathy Caused by Defective Membrane Remodelling of Dynamin 2 and BIN1 Variants

“…We also observed that membrane fission occurs between the clustered dynamin helices proposing a novel “clusterase model” [ 72 ]. GTP hydrolysis also causes the twisting motion of the dynamin helical polymer that provides torsion at the neck of the endocytic pits to promote membrane fission [ 73 , 74 ]. Thus, dynamin severs membrane by a combination of various mechanical stresses caused by structural changes and depolymerisation upon GTP hydrolysis.…”