title: Active solubilization and refolding of stable protein aggregates by cooperative unfolding action of individual hsp70 chaperones.
abstract: Hsp70 is a central molecular chaperone that passively prevents protein aggregation and uses the energy of ATP hydrolysis to solubilize, translocate, and mediate the proper refolding of proteins in the cell. Yet, the molecular mechanism by which the active Hsp70 chaperone functions are achieved remains unclear. Here, we show that the bacterial Hsp70 (DnaK) can actively unfold misfolded structures in aggregated polypeptides, leading to gradual disaggregation. We found that the specific unfolding and disaggregation activities of individual DnaK molecules were optimal for large aggregates but dramatically decreased for small aggregates. The active unfolding of the smallest aggregates, leading to proper global refolding, required the cooperative action of several DnaK molecules per misfolded polypeptide. This finding suggests that the unique ATP-fueled locking/unlocking mechanism of the Hsp70 chaperones can recruit random chaperone motions to locally unfold misfolded structures and gradually disentangle stable aggregates into refoldable proteins.
authors.affiliation: Départment de Biologie Moléculaire Végétale, Université de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Anat
authors.initials: A
authors.lastname: Ben-Zvi
authors.forename: Paolo
authors.initials: P
authors.lastname: De Los Rios
authors.forename: Giovanni
authors.initials: G
authors.lastname: Dietler
authors.forename: Pierre
authors.initials: P
authors.lastname: Goloubinoff
mesh_terms: D002850:Chromatography, Gel; D029968:Escherichia coli Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D007934:Leuconostoc / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D012995:Solubility
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; C063842:dnaK protein, E coli