title: Structure of the substrate binding domain of the thermosome, an archaeal group II chaperonin.
abstract: 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.
authors.affiliation: Department of Molecular Structural Biology, Max-Planck-Institute for Biochemistry, Planegg-Martinsried, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Klumpp
authors.forename: W
authors.initials: W
authors.lastname: Baumeister
authors.forename: L O
authors.initials: LO
authors.lastname: Essen
mesh_terms: D001105:Archaea / Q000737:chemistry* / Q000648:ultrastructure; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000648:ultrastructure; D001665:Binding Sites; D018833:Chaperonins / Q000737:chemistry* / Q000235:genetics* / Q000648:ultrastructure; D003461:Crystallography; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid
chemical_list: D019843:Archaeal Proteins; D018833:Chaperonins