Abstract
The recycling of SNARE proteins following complex formation and membrane fusion is an essential process in eukaryotic trafficking. A highly conserved AAA+ protein, NSF (N-ethylmaleimide sensitive factor) and an adaptor protein, SNAP (soluble NSF attachment protein), disassemble the SNARE complex. We report electron-cryomicroscopy structures of the complex of NSF, αSNAP, and the full-length soluble neuronal SNARE complex (composed of syntaxin-1A, synaptobrevin-2, SNAP-25A) in the presence of ATP under non-hydrolyzing conditions at ~3.9 Å resolution. These structures reveal electrostatic interactions by which two αSNAP molecules interface with a specific surface of the SNARE complex. This interaction positions the SNAREs such that the 15 N-terminal residues of SNAP-25A are loaded into the D1 ring pore of NSF via a spiral pattern of interactions between a conserved tyrosine NSF residue and SNAP-25A backbone atoms. This loading process likely precedes ATP hydrolysis. Subsequent ATP hydrolysis then drives complete disassembly.
Highlights
IntroductionThe archetypal Type II AAA+ protein NSF (N-ethylmaleimide-sensitive-factor) plays an essential role in eukaryotic trafficking through its disassembly of different SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes (Zhao and Brunger, 2016)
The archetypal Type II AAA+ protein NSF (N-ethylmaleimide-sensitive-factor) plays an essential role in eukaryotic trafficking through its disassembly of different SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes (Zhao and Brunger, 2016). This process has been studied extensively in the context of neurotransmission, where synaptic vesicle fusion with the presynaptic membrane is driven by the formation of the ternary neuronal SNARE complex, an exceptionally stable four-helix bundle composed of syntaxin, synaptobrevin, and SNAP-25 (Fasshauer et al, 1998; Sutton et al, 1998; Weber et al, 1998)
The 20S complex was prepared in a manner similar to that described previously (Zhao et al, 2015) using hexameric NSF, aSNAP, and nearly full-length soluble neuronal SNARE complex
Summary
The archetypal Type II AAA+ protein NSF (N-ethylmaleimide-sensitive-factor) plays an essential role in eukaryotic trafficking through its disassembly of different SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes (Zhao and Brunger, 2016). This process has been studied extensively in the context of neurotransmission, where synaptic vesicle fusion with the presynaptic membrane is driven by the formation of the ternary neuronal SNARE complex, an exceptionally stable four-helix bundle composed of syntaxin, synaptobrevin, and SNAP-25 (Fasshauer et al, 1998; Sutton et al, 1998; Weber et al, 1998).
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