PURIFICATION AND STRUCTURAL CHARACTERIZATION OF THE THERMOSOME FROM THE HYPERTHERMOPHILIC ARCHAEUM METHANOPYRUS-KANDLERI

From Methanopyras kandleri, the most thermophilic methanogen known so far, we have purified to homogeneity a protein complex of high molecul ar mass. Image analysis of transmission electron micrographs revealed a barrel-shaped particle composed of two rings with 8-fold symmetry. O nly one type of subunit could be detected, The corresponding gene has been cloned and sequenced. The deduced amino acid sequence shows high homology with the members of group II chaperonins. The structure of th e projection and the sequence homology suggest that this particle is t he first thermosome isolated from a methanogen.