The human cytosolic molecular chaperones hsp90, hsp70 (hsc70) and hdj-1 have distinct roles in recognition of a non-native protein and protein refolding

EMBO J. 1996 Jun 17;15(12):2969-79.

Abstract

The properties of molecular chaperones in protein-assisted refolding were examined in vitro using recombinant human cytosolic chaperones hsp90, hsc70, hsp70 and hdj-1, and unfolded beta-galactosidase as the substrate. In the presence of hsp70 (hsc70), hdj-1 and either ATP or ADP, denatured beta-galactosidase refolds and forms enzymatically active tetramers. Interactions between hsp90 and non-native beta-galactosidase neither lead to refolding nor stimulate hsp70- and hdj-1-dependent refolding. However, hsp90 in the absence of nucleotide can maintain the non-native substrate in a 'folding-competent' state which, upon addition of hsp70, hdj-1 and nucleotide, leads to refolding. The refolding activity of hsp70 and hdj-1 is effective across a broad range of temperatures from 22 degrees C to 41 degrees C, yet at extremely low (4 degrees C) or high (>41 degrees C) temperatures refolding activity is reversibly inhibited. These results reveal two distinct features of chaperone activity in which a non-native substrate can be either maintained in a stable folding-competent state or refolded directly to the native state; first, that the refolding activity itself is temperature sensitive and second, that hsp90, hsp70 (hsc70) and hdj-1 each have distinct roles in these processes.

Publication types

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

MeSH terms

  • Adenine Nucleotides / physiology
  • Animals
  • Baculoviridae / genetics
  • Cell Line
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins / metabolism
  • HSP70 Heat-Shock Proteins / physiology*
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism
  • HSP90 Heat-Shock Proteins / physiology*
  • Heat-Shock Proteins*
  • Humans
  • Molecular Chaperones / metabolism
  • Molecular Chaperones / physiology*
  • Protein Binding
  • Protein Folding*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Spodoptera
  • Temperature
  • beta-Galactosidase / metabolism

Substances

  • Adenine Nucleotides
  • DNAJB1 protein, human
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Recombinant Proteins
  • beta-Galactosidase