scholarly journals Mechanistic insights into the SNARE complex disassembly

2019 ◽  
Vol 5 (4) ◽  
pp. eaau8164 ◽  
Author(s):  
Xuan Huang ◽  
Shan Sun ◽  
Xiaojing Wang ◽  
Fenghui Fan ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Snare Complex ◽  
Amino Terminus ◽  
Receptor Complex ◽  
Attachment Protein ◽  
Helical Bundle ◽  
Disassembly Process ◽  
Protein Receptor ◽  
Sensitive Factor

NSF (N-ethylmaleimide–sensitive factor) and α-SNAP (α–soluble NSF attachment protein) bind to the SNARE (soluble NSF attachment protein receptor) complex, the minimum machinery to mediate membrane fusion, to form a 20S complex, which disassembles the SNARE complex for reuse. We report the cryo-EM structures of the α-SNAP–SNARE subcomplex and the NSF-D1D2 domain in the 20S complex at 3.9- and 3.7-Å resolutions, respectively. Combined with the biochemical and electrophysiological analyses, we find that α-SNAPs use R116 through electrostatic interactions and L197 through hydrophobic interactions to apply force mainly on two positions of the VAMP protein to execute disassembly process. Furthermore, we define the interaction between the amino terminus of the SNARE helical bundle and the pore loop of the NSF-D1 domain and demonstrate its essential role as a potential anchor for SNARE complex disassembly. Our studies provide a rotation model of α-SNAP–mediated disassembly of the SNARE complex.

scholarly journals How Could SNARE Proteins Open a Fusion Pore?

Physiology ◽  
2014 ◽  
Vol 29 (4) ◽  
pp. 278-285 ◽  
Author(s):  
Qinghua Fang ◽  
Manfred Lindau
Keyword(s):  
Conformational Change ◽  
Pore Formation ◽  
Vesicle Fusion ◽  
Neurosecretory Cells ◽  
Snare Complex ◽  
Snare Proteins ◽  
Fusion Pore ◽  
Receptor Complex ◽  
Attachment Protein ◽  
Protein Receptor

The SNARE (Soluble NSF Attachment protein REceptor) complex, which in mammalian neurosecretory cells is composed of the proteins synaptobrevin 2 (also called VAMP2), syntaxin, and SNAP-25, plays a key role in vesicle fusion. In this review, we discuss the hypothesis that, in neurosecretory cells, fusion pore formation is directly accomplished by a conformational change in the SNARE complex via movement of the transmembrane domains.

scholarly journals Regulation of exocytosis by the exocyst subunit Sec6 and the SM protein Sec1

2012 ◽  
Vol 23 (2) ◽  
pp. 337-346 ◽  
Author(s):  
Francesca Morgera ◽  
Margaret R. Sallah ◽  
Michelle L. Dubuke ◽  
Pallavi Gandhi ◽  
Daniel N. Brewer ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Secretory Pathway ◽  
Secretory Vesicle ◽  
Snare Complex ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Membrane Bound ◽  
Sm Protein ◽  
Snare Complex Formation

Trafficking of protein and lipid cargo through the secretory pathway in eukaryotic cells is mediated by membrane-bound vesicles. Secretory vesicle targeting and fusion require a conserved multisubunit protein complex termed the exocyst, which has been implicated in specific tethering of vesicles to sites of polarized exocytosis. The exocyst is directly involved in regulating soluble N-ethylmaleimide–sensitive factor (NSF) attachment protein receptor (SNARE) complexes and membrane fusion through interactions between the Sec6 subunit and the plasma membrane SNARE protein Sec9. Here we show another facet of Sec6 function—it directly binds Sec1, another SNARE regulator, but of the Sec1/Munc18 family. The Sec6–Sec1 interaction is exclusive of Sec6–Sec9 but compatible with Sec6–exocyst assembly. In contrast, the Sec6–exocyst interaction is incompatible with Sec6–Sec9. Therefore, upon vesicle arrival, Sec6 is proposed to release Sec9 in favor of Sec6–exocyst assembly and to simultaneously recruit Sec1 to sites of secretion for coordinated SNARE complex formation and membrane fusion.

scholarly journals Interaction of SNAREs with ArfGAPs Precedes Recruitment of Sec18p/NSF

2007 ◽  
Vol 18 (8) ◽  
pp. 2852-2863 ◽  
Author(s):  
Christina Schindler ◽  
Anne Spang
Keyword(s):  
Conformational Change ◽  
Atp Hydrolysis ◽  
Small Gtpase ◽  
Snare Complex ◽  
Coat Proteins ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Target Membrane

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are key components of the fusion machinery in vesicular transport and in homotypic membrane fusion. We previously found that ADP-ribosylation factor GTPase activating proteins (ArfGAPs) promoted a conformational change on SNAREs that allowed recruitment of the small GTPase Arf1p in stoichiometric amounts. Here, we show that the ArfGAP Gcs1p accelerates vesicle (v)-target membrane (t)-SNARE complex formation in vitro, indicating that ArfGAPs may act as folding chaperones. These SNARE complexes were resolved in the presence of ATP by the yeast homologues of α-soluble N-ethylmaleimide-sensitive factor attachment protein and N-ethylmaleimide-sensitive factor, Sec17p and Sec18p, respectively. In addition, Sec18p and Sec17p also recognized the “activated” SNAREs even when they were not engaged in v-t-SNARE complexes. Here again, the induction of a conformational change by ArfGAPs was essential. Surprisingly, recruitment of Sec18p to SNAREs did not require Sec17p or ATP hydrolysis. Moreover, Sec18p displaced prebound Arf1p from SNAREs, indicating that Sec18p may have more than one function: first, to ensure that all vesicle coat proteins are removed from the SNAREs before the engagement in a trans-SNARE complex; and second, to resolve cis-SNARE complexes after fusion has occurred.

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