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

• DOI: 10.7554/elife.31324
• Publication Date: 2017-11-22T13:02:30Z
• Authors: Han Han; Nicole Monroe; Wesley I Sundquist; Peter S Shen; Christopher P Hill
• Keywords: Adenosine Triphosphatases; Models, Molecular; 0301 basic medicine; Saccharomyces cerevisiae Proteins; Endosomal Sorting Complexes Required for Transport; QH301-705.5; Protein Conformation; membrane fission; Science; Q; Cryoelectron Microscopy; R; ESCRT pathway; 03 medical and health sciences; Biochemistry and Chemical Biology; cryo-EM; Medicine; structure; AAA ATPase; Biology (General); Protein Binding

The hexameric AAA ATPase Vps4 drives membrane fission by remodeling and disassembling ESCRT-III filaments. Building upon our earlier 4.3 Å resolution cryo-EM structure (<xref ref-type="bibr" rid="bib29">Monroe et al., 2017</xref>), we now report a 3.2 Å structure of Vps4 bound to an ESCRT-III peptide substrate. The new structure reveals that the peptide approximates a β-strand conformation whose helical symmetry matches that of the five Vps4 subunits it contacts directly. Adjacent Vps4 subunits make equivalent interactions with successive substrate dipeptides through two distinct classes of side chain binding pockets formed primarily by Vps4 pore loop 1. These pockets accommodate a wide range of residues, while main chain hydrogen bonds may help dictate substrate-binding orientation. The structure supports a ‘conveyor belt’ model of translocation in which ATP binding allows a Vps4 subunit to join the growing end of the helix and engage the substrate, while hydrolysis and release promotes helix disassembly and substrate release at the lagging end.