title: Atypical AAA+ subunit packing creates an expanded cavity for disaggregation by the protein-remodeling factor Hsp104.
abstract: Hsp104, a yeast protein-remodeling factor of the AAA+ (ATPases associated with various cellular activities) superfamily, and its homologs in bacteria and plants mediate cell recovery after severe stress by disaggregating denatured proteins through a poorly understood mechanism. Here, we present cryo-electron microscopy maps and domain fitting of Hsp104 hexamers, revealing an unusual arrangement of AAA+ modules with the prominent coiled-coil domain intercalated between the AAA+ domains. This packing results in a greatly expanded cavity, which is capped at either end by N- and C-terminal domains. The fitted structures as well as mutation of conserved coiled-coil arginines suggest that the coiled-coil domain plays a major role in the extraction of proteins from aggregates, providing conserved residues for key functions in ATP hydrolysis and potentially for substrate interaction. The large cavity could enable the uptake of polypeptide loops without a requirement for exposed N or C termini.
authors.affiliation: Department of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.
authors.forename: Petra
authors.initials: P
authors.lastname: Wendler
authors.forename: James
authors.initials: J
authors.lastname: Shorter
authors.forename: Celia
authors.initials: C
authors.lastname: Plisson
authors.forename: Anil G
authors.initials: AG
authors.lastname: Cashikar
authors.forename: Susan
authors.initials: S
authors.lastname: Lindquist
authors.forename: Helen R
authors.initials: HR
authors.lastname: Saibil
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D017124:Conserved Sequence; D020285:Cryoelectron Microscopy; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D021621:Imaging, Three-Dimensional; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D012996:Solutions
chemical_list: D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D021122:Protein Subunits; D012996:Solutions; D000255:Adenosine Triphosphate; D001120:Arginine; D008666:Metalloendopeptidases; C114583:m-AAA proteases