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Free keywords:
Chaperone; Thermosome; Heat shock; Electron cryo-microscopy; Archaea.; T-complex polypeptide-1; Molecular chaperone; Thermophilic archaebacterium; Cytoplasmic chaperonin; Cytosolic chaperonin; Electron-microscopy; Eukaryotic cytosol; Escherichia-coli; Central cavity; Heat-shock.; Molecular biology & genetics.
Abstract:
The thermosome of the archaeon Thermoplasma acidophilum is composed of two subunits, alpha and beta, which are arranged in two stacked, eight-membered rings. Electron cryo-microscopy in conjunction with image analysis revealed a 4-fold symmetry in the heterooligomeric alpha + beta thermosome isolated from Thermoplasma, but not in the homooligomeric alpha-only thermosome expressed in Escherichia coli. This indicates that alpha and P-subunits alternate within the rings of the Thermoplasma thermosome rather than forming two different homooligomeric rings. In addition, a small subpopulation of 9-fold symmetric complexes was found among the recombinant alpha-only thermosomes, and a central mass most likely representing bound substrate molecules was observed in about half of the native and recombinant thermosome particles. (C) 1997 Academic Press Limited. [References: 36]
