title: Primary structure of the thermosome from Thermoplasma acidophilum.
abstract: The thermosome, a chaperonin from the archaebacterium Thermoplasma acidophilum, consists of two subunits (M(r) 58,000 and 60,000) which assemble into a cylindrical complex of pseudo eight-fold rotational symmetry. The sequences of the two subunits are approximately 60% identical to each other and to TF55 from Sulfolobus shibatae, and are 30-40% identical to the subunits of the TCP1 containing ring complex (TRiC) from the eukaryotic cytosol. A dendrogram of this family of chaperonins contains eight eukaryotic branches of TRiC subunits and one archaebacterial branch of thermosome subunits. Alignment of thermosome/TRiC sequences with eubacterial and eukaryotic Hsp60 sequences reveals a statistically significant similarity in two large N- and C-terminal blocks of sequence. Based on this alignment and on the recently published crystal structure of GroEL, we propose that subunits of the thermosome/TRiC family of chaperonins have a similar equatorial domain and overall domain topology as GroEL but differ in the structure of the apical domain.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Waldmann
authors.forename: A
authors.initials: A
authors.lastname: Lupas
authors.forename: J
authors.initials: J
authors.lastname: Kellermann
authors.forename: J
authors.initials: J
authors.lastname: Peters
authors.forename: W
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018834:Chaperonin 60 / Q000737:chemistry; D018833:Chaperonins / Q000737:chemistry*; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000737:chemistry*; D013822:Thermoplasma / Q000737:chemistry*
chemical_list: D018834:Chaperonin 60; D018833:Chaperonins