Continuum architecture dynamics of vesicle tethering in exocytosis

ABSTRACT: Essential for eukaryotes, multiple copies of the exocyst complex tether each secretory vesicle to the plasma membrane (PM) in constitutive exocytosis. The exocyst higher-order structure (ExHOS) that coordinates the action of these multiple exocysts remains unexplored. We integrated particle tracking, super-resolution microscopy and cryo-electron tomography to time- resolve the continuum conformational landscape of the ExHOS and to functionally annotate its different conformations. We found that 7 exocysts form flexible ring-shaped ExHOS that tether 2 vesicles at <45 nm from the PM. The ExHOS rapidly expands while it pulls the vesicle towards the PM in a stepwise mechanism comprising three metastable states at 27, 18 and 5 nm from the PM. After fusion, Sec18 mediates the disassembly of the stationary ExHOS, an emergent function that controls the rate of exocytosis. By resolving the biophysical principles of tethering we bridged the gap between static isolated structures and the dynamic and multimeric nature of exocytosis. This datset contains in particular the correlative light and electorn microscopy images of lamellae that were subsequently used to target tomogram acqusition.

SUBMITTER: Oriol Gallego 

PROVIDER: S-BIAD2259 | bioimages |

REPOSITORIES: bioimages