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Publication Abstract from PubMed

The crystal structure of the beta-apical domain of the thermosome, an archaeal group II chaperonin from Thermoplasma acidophilum, has been determined at 2.8 A resolution. The structure shows an invariant globular core from which a 25 A long protrusion emanates, composed of an elongated alpha-helix (H10) and a long extended stretch consisting of residues GluB245-ThrB253. A comparison with previous apical domain structures reveals a large segmental displacement of the protruding part of helix H10 via the hinge GluB276-ValB278. The region comprising residues GluB245-ThrB253 adopts an extended beta-like conformation rather than the alpha-helix seen in the alpha-apical domain. Consequently, it appears that the protrusions of the apical domains from group II chaperonins might assume a variety of context-dependent conformations during an open, substrate-accepting state of the chaperonin. Sequence variations in the protrusion regions that are found in the eukaryotic TRiC/CCT subunits may provide different structural propensities and hence serve different roles in substrate recognition.

Crystal structure of the beta-apical domain of the thermosome reveals structural plasticity in the protrusion region.,Bosch G, Baumeister W, Essen LO J Mol Biol. 2000 Aug 4;301(1):19-25. PMID:10926489^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.