Mechanistic insights into the SNARE complex disassembly

NSF (N-ethylmaleimide-sensitive factor) and alpha-SNAP (alpha-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 alpha-SNAP-SNARE subcomplex and the NSF-D1D2 domain in the 20S complex at 3.9- and 3.7-angstrom resolutions, respectively. Combined with the biochemical and electrophysiological analyses, we find that alpha-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 alpha-SNAP-mediated disassembly of the SNARE complex.