Review: mechanisms of disaggregation and refolding of stable protein aggregates by molecular chaperones

J Struct Biol. 2001 Aug;135(2):84-93. doi: 10.1006/jsbi.2001.4352.

Abstract

Molecular chaperones are essential for the correct folding of proteins in the cell under physiological and stress conditions. Two activities have been traditionally attributed to molecular chaperones: (1) preventing aggregation of unfolded polypeptides and (2) assisting in the correct refolding of chaperone-bound denatured polypeptides. We discuss here a novel function of molecular chaperones: catalytic solubilization and refolding of stable protein aggregates. In Escherichia coli, disaggregation is carried out by a network of ATPase chaperones consisting of a DnaK core, assisted by the cochaperones DnaJ, GrpE, ClpB, and GroEL-GroES. We suggest a sequential mechanism in which (a) ClpB exposes new DnaK-binding sites on the surface of the stable protein aggregates; (b) DnaK binds the aggregate surfaces and, by doing so, melts the incorrect hydrophobic associations between aggregated polypeptides; (c) ATP hydrolysis and DnaK release allow local intramolecular refolding of native domains, leading to a gradual weakening of improper intermolecular links; (d) DnaK and GroEL complete refolding of solubilized polypeptide chains into native proteins. Thus, active disaggregation by the chaperone network can serve as a central cellular tool for the recovery of native proteins from stress-induced aggregates and actively remove disease-causing toxic aggregates, such as polyglutamine-rich proteins, amyloid plaques, and prions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Adenosine Triphosphatases / pharmacology
  • Adenosine Triphosphatases / physiology
  • Animals
  • Humans
  • Macromolecular Substances
  • Molecular Chaperones / pharmacology
  • Molecular Chaperones / physiology*
  • Protein Folding
  • Protein Renaturation / drug effects*

Substances

  • Macromolecular Substances
  • Molecular Chaperones
  • Adenosine Triphosphatases