Structure of the substrate binding domain of the thermosome, an archaeal group II chaperonin

Cell. 1997 Oct 17;91(2):263-70. doi: 10.1016/s0092-8674(00)80408-0.


The crystal structure of the substrate binding domain of the thermosome, the archaeal group II chaperonin, has been determined at 2.3 A resolution. The core resembles the apical domain of GroEL but lacks the hydrophobic residues implied in binding of substrates to group I chaperonins. Rather, a large hydrophobic surface patch is found in a novel helix-turn-helix motif, which is characteristic of all group II chaperonins including the eukaryotic TRiC/CCT complex. Models of the holochaperonin, which are consistent with cryo electron microscopy data, suggest a dual role of this helical protrusion in substrate binding and controlling access to the central cavity independent of a GroES-like cochaperonin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaea / chemistry*
  • Archaea / ultrastructure
  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / genetics*
  • Archaeal Proteins / ultrastructure
  • Binding Sites
  • Chaperonins / chemistry*
  • Chaperonins / genetics*
  • Chaperonins / ultrastructure
  • Crystallography
  • Microscopy, Electron
  • Molecular Sequence Data
  • Protein Conformation
  • Protein Structure, Secondary
  • Sequence Homology, Amino Acid


  • Archaeal Proteins
  • Chaperonins

Associated data

  • PDB/1ASS
  • PDB/1ASX