The AAA ATPase Vps4 binds ESCRT-III substrates through a repeating array of dipeptide-binding pockets.

Area of Science:

• Biochemistry
• Cell Biology
• Structural Biology

Background:

• The AAA ATPase Vps4 is crucial for membrane fission by remodeling ESCRT-III filaments.
• Previous studies provided a lower-resolution structure of Vps4.

Purpose of the Study:

• To determine the high-resolution structure of Vps4 bound to an ESCRT-III peptide substrate.
• To elucidate the molecular mechanism of ESCRT-III filament disassembly by Vps4.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to obtain a 3.2 Å resolution structure.
• Structural analysis of Vps4-ESCRT-III peptide interactions.

Main Results:

• A 3.2 Å structure of Vps4 bound to an ESCRT-III peptide was determined.
• The ESCRT-III peptide adopts a β-strand conformation, interacting with five Vps4 subunits.
• Specific binding pockets in Vps4 (pore loop 1) accommodate diverse residues, with main chain hydrogen bonds orienting the substrate.
• A 'conveyor belt' model for ATP-dependent translocation and disassembly is supported.

Conclusions:

• The structure provides detailed insights into Vps4-mediated ESCRT-III filament disassembly.
• The findings support a model where Vps4 uses ATP binding and hydrolysis to translocate and disassemble the filament.
• This mechanism is key for membrane fission processes.