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Nat Commun. 2013;4:1705. doi: 10.1038/ncomms2692.

Mechanical unzipping and rezipping of a single SNARE complex reveals hysteresis as a force-generating mechanism.

Author information

1
National Creative Research Initiative Center for Single-Molecule Systems Biology, KAIST, Daejeon 305-701, South Korea.

Abstract

Formation of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex provides mechanical thrust for membrane fusion, but its molecular mechanism is still unclear. Here using magnetic tweezers, we observe mechanical responses of a single neuronal SNARE complex under constant pulling force. Single SNARE complexes may be unzipped with 34 pN force. When rezipping is induced by lowering the force to 11 pN, only a partially assembled state results, with the C-terminal half of the SNARE complex remaining disassembled. Reassembly of the C-terminal half occurs only when the force is further lowered below 11 pN. Thus, mechanical hysteresis, characterized by the unzipping and rezipping cycle of a single SNARE complex, produces the partially assembled state. In this metastable state, unzipping toward the N-terminus is suppressed while zippering toward the C-terminus is initiated as a steep function of force. This ensures the directionality of SNARE-complex formation, making the SNARE complex a robust force-generating machine.

PMID:
23591872
PMCID:
PMC3644077
DOI:
10.1038/ncomms2692
[Indexed for MEDLINE]
Free PMC Article

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