title: Molecular chaperones as enzymes that catalytically unfold misfolded polypeptides.
abstract: Stress-denatured or de novo synthesized and translocated unfolded polypeptides can spontaneously reach their native state without assistance of other proteins. Yet, the pathway to native folding is complex, stress-sensitive and prone to errors. Toxic misfolded and aggregated conformers may accumulate in cells and lead to degenerative diseases. Members of the canonical conserved families of molecular chaperones, Hsp100s, Hsp70/110/40s, Hsp60/CCTs, the small Hsps and probably also Hsp90s, can recognize and bind with high affinity, abnormally exposed hydrophobic surfaces on misfolded and aggregated polypeptides. Binding to Hsp100, Hsp70, Hsp110, Hsp40, Hsp60, CCTs and Trigger factor may cause partial unfolding of the misfolded polypeptide substrates, and ATP hydrolysis can induce further unfolding and release from the chaperone, leading to spontaneous refolding into native proteins with low-affinity for the chaperones. Hence, specific chaperones act as catalytic polypeptide unfolding isomerases, rerouting cytotoxic misfolded and aggregated polypeptides back onto their physiological native refolding pathway, thus averting the onset of protein conformational diseases.
authors.affiliation: Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Smriti
authors.initials: S
authors.lastname: Priya
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Sharma
authors.forename: Pierre
authors.initials: P
authors.lastname: Goloubinoff
mesh_terms: D000818:Animals; D055162:Biocatalysis; D018833:Chaperonins / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000502:physiology; D006801:Humans; D010455:Peptides / Q000378:metabolism*; D058767:Protein Unfolding; D057165:Proteostasis Deficiencies / Q000201:enzymology
chemical_list: D006360:Heat-Shock Proteins; D010455:Peptides; D018833:Chaperonins