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Synaptotagmin oligomers are necessary and can be sufficient to form a Ca2+ -sensitive fusion clamp.

ABSTRACT: The buttressed-ring hypothesis, supported by recent cryo-electron tomography analysis of docked synaptic-like vesicles in neuroendocrine cells, postulates that prefusion SNAREpins are stabilized and organized by Synaptotagmin (Syt) ring-like oligomers. Here, we use a reconstituted single-vesicle fusion analysis to test the prediction that destabilizing the Syt1 oligomers destabilizes the clamp and results in spontaneous fusion in the absence of Ca2+ . Vesicles in which Syt oligomerization is compromised by a ring-destabilizing mutation dock and diffuse freely on the bilayer until they fuse spontaneously, similar to vesicles containing only v-SNAREs. In contrast, vesicles containing wild-type Syt are immobile as soon as they attach to the bilayer and remain frozen in place, up to at least 1 h until fusion is triggered by Ca2+ .

SUBMITTER: Ramakrishnan S

PROVIDER: S-EPMC6349546 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Synaptotagmin oligomers are necessary and can be sufficient to form a Ca2+ -sensitive fusion clamp.

Ramakrishnan Sathish S Bera Manindra M Coleman Jeff J Krishnakumar Shyam S SS Pincet Frederic F Rothman James E JE

FEBS letters 20190118 2

The buttressed-ring hypothesis, supported by recent cryo-electron tomography analysis of docked synaptic-like vesicles in neuroendocrine cells, postulates that prefusion SNAREpins are stabilized and organized by Synaptotagmin (Syt) ring-like oligomers. Here, we use a reconstituted single-vesicle fusion analysis to test the prediction that destabilizing the Syt1 oligomers destabilizes the clamp and results in spontaneous fusion in the absence of Ca2+ . Vesicles in which Syt oligomeriza ...[more]

PMID: 30570144

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