Deconstruction of stable cross-Beta fibrillar structures into toxic and nontoxic products using a mutated archaeal chaperonin.

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TitleDeconstruction of stable cross-Beta fibrillar structures into toxic and nontoxic products using a mutated archaeal chaperonin.
Publication TypeJournal Article
Year of Publication2013
AuthorsKurouski, D, Luo, H, Sereda, V, Robb, FT, Lednev, IK
JournalACS Chem Biol
Volume8
Issue9
Pagination2095-101
Date Published2013 Sep 20
ISSN1554-8937
KeywordsAdenosine Triphosphate, Amyloid, Animals, Archaea, Archaeal Proteins, Cell Line, Tumor, Chaperonin 60, Humans, Insulin, Models, Molecular, Mutation, Protein Conformation, Protein Folding
Abstract

Our group recently determined that a mutant archaeal chaperonin (Hsp 60) exhibited substantially enhanced protein folding activity at low temperatures and was able to deconstruct refractory protein aggregates. ATP dependent conversion of fibril structures into amorphous aggregates was observed in insulin amyloid preparations (Kurouski et al. Biochem. Biophys. Res. Commun. 2012). In the current study, mechanistic insights into insulin fibril deconstruction were obtained by examination of early stage complexes between Hsp60 and fibrils in the absence of ATP. Activity of the Hsp60 was significantly curtailed without ATP; however, some fibril deconstruction occurred, which is consistent with some models of the folding cycle that predict initial removal of unproductive protein folds. Chaperonin molecules adsorbed on the fibril surface and formed chaperonin clusters with no ATP present. We propose that there are specific locations on the fibril surface where chaperonin can unravel the fibril to release short fragments. Spontaneous coagulation of these fibril fragments resulted in the formation of amorphous aggregates without the release of insulin into solution. The addition of ATP significantly increased the toxicity of the insulin fibril-chaperonin reaction products toward mammalian cells.

DOI10.1021/cb400238a
Alternate JournalACS Chem. Biol.
PubMed ID23875676