SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins involved in membrane fusion usually contain a conserved alpha-helix (SNARE motif) that is flanked by a C-terminal transmembrane domain. They can be classified into Q-SNARE and R-SNARE based on the structural property of their motifs. Assembly of four SNARE motifs (Qa, b, c and R) is supposed to trigge...

To enable fusion between biological membranes, t-SNAREs and v-SNARE present in opposing bilayers, interact and assemble in a circular configuration forming ring-complexes, which establish continuity between the opposing membranes, in presence of calcium ions. The size of a t-/v-SNARE ring complex is dictated by the curvature of the opposing membrane. Hence smaller vesicles form small SNARE-ring...

At physiological protein levels, the slow HOPS- and SNARE-dependent fusion which occurs upon complete SNARE zippering is stimulated by Sec17 and Sec18:ATP without requiring ATP hydrolysis. To stimulate, Sec17 needs its central residues which bind the 0-layer of the SNARE complex and its N-terminal apolar loop. Adding a transmembrane anchor to the N-terminus of Sec17 bypasses this requirement fo...

Intracellular membrane fusion is mediated by the formation of a four-helix bundle comprised of SNARE proteins. Every cell expresses a large number of SNARE proteins that are localized to particular membrane compartments, suggesting that the fidelity of vesicle trafficking might in part be determined by specific SNARE pairing. However, the promiscuity of SNARE pairing in vitro suggests that the ...

SNARE proteins mediate membrane fusion in eukaryotic cells. They contain conserved SNARE motifs that are usually located adjacent to a C-terminal transmembrane domain. SNARE motifs spontaneously assemble into four helix bundles, with each helix belonging to a different subfamily. Liposomes containing SNAREs spontaneously fuse with each other, but it is debated how the SNAREs are distributed bet...

Background: NSF is an AAA protein that recycles the post-fusion SNARE complex during the membrane fusion cycle. Results: NSF disassembles the SNARE complex processively in vitro and consumes dozens of ATP molecules per SNARE. Conclusion: NSF is a processive motor that progressively unwinds the SNARE complex. Significance: The physical mechanism of this poorly understood machine is illuminated u...

Cholesterol has been proposed to play a critical role in regulating neurotransmitter release and synaptic plasticity. The neuronal porosome/fusion pore, the secretory machinery at the nerve terminal, is a 12-17 nm cup-shaped lipoprotein structure composed of cholesterol and a number of proteins, among them calcium channels, and the t-SNARE proteins Syntaxin-1 and SNAP-25. During neurotransmissi...

Fusion of intracellular transport vesicles requires soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and Sec1/Munc18-family (SM) proteins. Membrane-bridging SNARE complexes are critical for fusion, but their spontaneous assembly is inefficient and may require SM proteins in vivo. We report x-ray structures of Vps33, the SM subunit of the yeast homotypic fusion and...

Full length v-SNARE protein in lipid vesicles when exposed to t-SNARE-reconstituted lipid membrane results in the self-assembly of a t-/v-SNARE complex in a ring pattern, forming pores, and establishing continuity between the opposing bilayers. It is known that smaller vesicles fuse more efficiently than larger ones, and hence the curvature of secretory vesicles may dictate the potency and effi...

During spermiogenesis, hydrolytic enzymes are sorted from the Golgi apparatus to the acrosome, a supranuclear megavesicle. At fertilization, the enzymatic content of the acrosome is released by exocytosis when a portion of the plasma membrane enveloping the sperm head fuses with the outer membrane of the acrosome. Membrane fusion involves the interaction of a specific pair of proteins, called S...