title: Conserved distal loop residues in the Hsp104 and ClpB middle domain contact nucleotide-binding domain 2 and enable Hsp70-dependent protein disaggregation.
abstract: The homologous hexameric AAA(+) proteins, Hsp104 from yeast and ClpB from bacteria, collaborate with Hsp70 to dissolve disordered protein aggregates but employ distinct mechanisms of intersubunit collaboration. How Hsp104 and ClpB coordinate polypeptide handover with Hsp70 is not understood. Here, we define conserved distal loop residues between middle domain (MD) helix 1 and 2 that are unexpectedly critical for Hsp104 and ClpB collaboration with Hsp70. Surprisingly, the Hsp104 and ClpB MD distal loop does not contact Hsp70 but makes intrasubunit contacts with nucleotide-binding domain 2 (NBD2). Thus, the MD does not invariably project out into solution as in one structural model of Hsp104 and ClpB hexamers. These intrasubunit contacts as well as those between MD helix 2 and NBD1 are different in Hsp104 and ClpB. NBD2-MD contacts dampen disaggregase activity and must separate for protein disaggregation. We demonstrate that ClpB requires DnaK more stringently than Hsp104 requires Hsp70 for protein disaggregation. Thus, we reveal key differences in how Hsp104 and ClpB coordinate polypeptide handover with Hsp70, which likely reflects differential tuning for yeast and bacterial proteostasis.
authors.affiliation: From the Department of Biochemistry and Biophysics and.
authors.forename: Morgan E
authors.initials: ME
authors.lastname: Desantis
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Sweeny
authors.forename: David
authors.initials: D
authors.lastname: Snead
authors.forename: Eunice H
authors.initials: EH
authors.lastname: Leung
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Go
authors.forename: Kushol
authors.initials: K
authors.lastname: Gupta
authors.forename: Petra
authors.initials: P
authors.lastname: Wendler
authors.forename: James
authors.initials: J
authors.lastname: Shorter
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053838:Scattering, Small Angle; D017386:Sequence Homology, Amino Acid; D014961:X-Ray Diffraction
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D049071:Endopeptidase Clp; C063842:dnaK protein, E coli; C069775:ClpB protein, E coli
keywords: ClpB; DNA; Disaggreg; Hsp104; Hsp70; Molecular Chaperone; Protein Aggregation; Protein Folding; Stress; Stress Response