title: The metazoan protein disaggregase and amyloid depolymerase system: Hsp110, Hsp70, Hsp40, and small heat shock proteins.
abstract: A baffling aspect of metazoan proteostasis is the lack of an Hsp104 ortholog that rapidly disaggregates and reactivates misfolded polypeptides trapped in stress induced disordered aggregates, preamyloid oligomers, or amyloid fibrils. By contrast, in bacteria, protozoa, chromista, fungi, and plants, Hsp104 orthologs are highly conserved and confer huge selective advantages in stress tolerance. Moreover, in fungi, the amyloid remodeling activity of Hsp104 has enabled deployment of prions for various beneficial modalities. Thus, a longstanding conundrum has remained unanswered: how do metazoan cells renature aggregated proteins or resolve amyloid fibrils without Hsp104? Here, we highlight recent advances that unveil the metazoan protein-disaggregase machinery, comprising Hsp110, Hsp70, and Hsp40, which synergize to dissolve disordered aggregates, but are unable to rapidly solubilize stable amyloid fibrils. However, Hsp110, Hsp70, and Hsp40 exploit the slow monomer exchange dynamics of amyloid, and can slowly depolymerize amyloid fibrils from their ends in a manner that is stimulated by small heat shock proteins. Upregulation of this system could have key therapeutic applications in various protein-misfolding disorders. Intriguingly, yeast Hsp104 can interface with metazoan Hsp110, Hsp70, and Hsp40 to rapidly eliminate disease associated amyloid. Thus, metazoan proteostasis is receptive to augmentation with exogenous disaggregases, which opens a number of therapeutic opportunities.
authors.affiliation: Department of Biochemistry and Biophysics; 805b Stellar-Chance Laboratories; Perelman School of Medicine; University of Pennsylvania; Philadelphia, PA USA.
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Torrente
authors.affiliation: Department of Biochemistry and Biophysics; 805b Stellar-Chance Laboratories; Perelman School of Medicine; University of Pennsylvania; Philadelphia, PA USA.
authors.forename: James
authors.initials: J
authors.lastname: Shorter
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D050957:HSP110 Heat-Shock Proteins / Q000378:metabolism*; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D019636:Neurodegenerative Diseases / Q000378:metabolism; D066329:Protein Aggregates; D066263:Protein Aggregation, Pathological / Q000378:metabolism*; D012995:Solubility
chemical_list: D000682:Amyloid; D050957:HSP110 Heat-Shock Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D066329:Protein Aggregates
keywords: Hsp104; Hsp110; Hsp70; metazoa; protein disaggregation