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Nat Struct Mol Biol. 2010 Jun;17(6):710-7. doi: 10.1038/nsmb.1809. Epub 2010 May 9.

The SM protein Vps33 and the t-SNARE H(abc) domain promote fusion pore opening.

Author information

1
Département de Biochimie, Université de Lausanne, Epalinges, Switzerland.

Abstract

Intracellular membrane fusion proceeds via distinct stages of membrane docking, hemifusion and fusion pore opening and depends on interacting families of Rab, SNARE and SM proteins. Trans-SNARE complexes dock the membranes in close apposition. Efficient fusion requires further SNARE-associated proteins. They might increase the number of trans-SNARE complexes or the fusogenic potential of a single SNARE complex. We investigated the contributions of the SM protein Vps33 to hemifusion and pore opening between yeast vacuoles. Mutations in Vps33 that weaken its interactions with the SNARE complex allowed normal trans-SNARE pairing and lipid mixing but retarded content mixing. Deleting the H(abc) domain of the vacuolar t-SNARE Vam3, which interacts with Vps33, had the same effect. This suggests that SM proteins promote fusion pore opening by enhancing the fusogenic activity of a SNARE complex. They should thus be considered integral parts of the fusion machinery.

PMID:
20453860
DOI:
10.1038/nsmb.1809
[Indexed for MEDLINE]

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