Crystal structure of the thermosome, the archaeal chaperonin and homolog of CCT

Cell. 1998 Apr 3;93(1):125-38. doi: 10.1016/s0092-8674(00)81152-6.


We have determined to 2.6 A resolution the crystal structure of the thermosome, the archaeal group II chaperonin from T. acidophilum. The hexadecameric homolog of the eukaryotic chaperonin CCT/TRiC shows an (alphabeta)4(alphabeta)4 subunit assembly. Domain folds are homologous to GroEL but form a novel type of inter-ring contact. The domain arrangement resembles the GroEL-GroES cis-ring. Parts of the apical domains form a lid creating a closed conformation. The lid substitutes for a GroES-like cochaperonin that is absent in the CCT/TRiC system. The central cavity has a polar surface implicated in protein folding. Binding of the transition state analog Mg-ADP-AIF3 suggests that the closed conformation corresponds to the ATP form.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Archaea / metabolism*
  • Archaeal Proteins*
  • Chaperonins / chemistry*
  • Chaperonins / metabolism*
  • Computer Simulation
  • Crystallography, X-Ray / methods
  • Intracellular Signaling Peptides and Proteins*
  • Macromolecular Substances
  • Microtubule-Associated Proteins*
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry*
  • Protein Conformation*
  • Protein Structure, Secondary*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Thermosomes
  • Ubiquitin-Protein Ligases
  • t-Complex Genome Region


  • Archaeal Proteins
  • Intracellular Signaling Peptides and Proteins
  • Macromolecular Substances
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • PPP1R11 protein, human
  • Ubiquitin-Protein Ligases
  • Chaperonins
  • Thermosomes

Associated data

  • PDB/1A6D
  • PDB/1A6E