Synaptic proteins promote calcium-triggered fast transition from point contact to full fusion

Jiajie Diao; Patricia Grob; Daniel J Cipriano; Minjoung Kyoung; Yunxiang Zhang; Sachi Shah; Amie Nguyen; Mark Padolina; Ankita Srivastava; Marija Vrljic; Ankita Shah; Eva Nogales; Steven Chu; Axel T Brunger

doi:10.7554/eLife.00109

eLife (Dec 2012)

Synaptic proteins promote calcium-triggered fast transition from point contact to full fusion

Jiajie Diao,
Patricia Grob,
Daniel J Cipriano,
Minjoung Kyoung,
Yunxiang Zhang,
Sachi Shah,
Amie Nguyen,
Mark Padolina,
Ankita Srivastava,
Marija Vrljic,
Ankita Shah,
Eva Nogales,
Steven Chu,
Axel T Brunger

Affiliations

Jiajie Diao: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Patricia Grob: Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, USA
Daniel J Cipriano: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Minjoung Kyoung: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Yunxiang Zhang: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Sachi Shah: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Amie Nguyen: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Mark Padolina: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Ankita Srivastava: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Marija Vrljic: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Ankita Shah: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA
Eva Nogales: Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, USA; Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, USA
Steven Chu: Formerly Lawrence Berkeley National Laboratory, and Departments of Physics and Molecular and Cell Biology, University of California at Berkeley, Berkeley, USA
Axel T Brunger: Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, Photon Science and Howard Hughes Medical Institute, Stanford University, Stanford, USA

DOI: https://doi.org/10.7554/eLife.00109
Journal volume & issue: Vol. 1

Abstract

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The molecular underpinnings of synaptic vesicle fusion for fast neurotransmitter release are still unclear. Here, we used a single vesicle–vesicle system with reconstituted SNARE and synaptotagmin-1 proteoliposomes to decipher the temporal sequence of membrane states upon Ca2+-injection at 250–500 μM on a 100-ms timescale. Furthermore, detailed membrane morphologies were imaged with cryo-electron microscopy before and after Ca2+-injection. We discovered a heterogeneous network of immediate and delayed fusion pathways. Remarkably, all instances of Ca2+-triggered immediate fusion started from a membrane–membrane point-contact and proceeded to complete fusion without discernible hemifusion intermediates. In contrast, pathways that involved a stable hemifusion diaphragm only resulted in fusion after many seconds, if at all. When complexin was included, the Ca2+-triggered fusion network shifted towards the immediate pathway, effectively synchronizing fusion, especially at lower Ca2+-concentration. Synaptic proteins may have evolved to select this immediate pathway out of a heterogeneous network of possible membrane fusion pathways.

Published in eLife

ISSN: 2050-084X (Online)
Publisher: eLife Sciences Publications Ltd
Country of publisher: United Kingdom
LCC subjects: Medicine; Science: Biology (General)
Website: https://elifesciences.org

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