Structural principles of SNARE complex recognition by the AAA+ protein NSF

Area of Science:

• Cellular Biology
• Structural Biology
• Biochemistry

Background:

• SNARE proteins mediate membrane fusion in eukaryotic cells.
• N-ethylmaleimide sensitive factor (NSF) and soluble NSF attachment protein (SNAP) are crucial for recycling SNARE complexes.
• Understanding the disassembly mechanism is key to cellular trafficking.

Purpose of the Study:

• To elucidate the structural mechanism of SNARE complex disassembly by NSF and αSNAP.
• To visualize the initial steps of SNARE complex loading onto NSF.
• To provide high-resolution structural insights into a critical cellular trafficking process.

Main Methods:

• Electron cryo-microscopy (cryo-EM) was used to determine the structure.
• The study focused on the complex of NSF, αSNAP, and the neuronal SNARE complex (syntaxin-1A, synaptobrevin-2, SNAP-25A).
• Structures were obtained in the presence of ATP under non-hydrolyzing conditions at ~3.9 Å resolution.

Main Results:

• Detailed structures of the NSF, αSNAP, and SNARE complex were resolved.
• Electrostatic interactions between αSNAP and the SNARE complex were identified.
• A spiral loading mechanism of SNAP-25A N-terminal residues into the NSF D1 ring pore was revealed, involving a conserved tyrosine residue.

Conclusions:

• The findings reveal the precise structural interactions facilitating SNARE complex disassembly.
• The identified loading mechanism precedes ATP hydrolysis, highlighting a key step in NSF function.
• This structural understanding is vital for comprehending the regulation of vesicular trafficking and membrane fusion in eukaryotes.