CHARACTERIZATION OF HOMOOLIGOMERIC COMPLEXES OF ALPHA-CHAPERONIN AND BETA-CHAPERONIN SUBUNITS FROM THE ACIDOTHERMOPHILIC ARCHAEON, SULFOLOBUS SP. STRAIN-7

The chaperonin from the acidothermopilic archaeon, Sulfolobus sp, Stra in 7, is composed of two kinds of subunits designated as Scp alpha and Scp beta. In this study, we characterized the recombinant Scp alpha a nd Scp beta, which were separately expressed in Escherichia coli, Both of them were able to assemble to homo-oligomeric double-ring complexe s, similar to subunits of group II chaperonins from Thermoplasma acido philum and Thermococcus strain KS-1, Both complexes have no or at most trace ATPase activities, However, they could arrest spontaneous refol ding of chemically denatured enzyme in the same way as the purified Su lfolobus chaperonin, We found that they dissociated in the presence of 15% ethanol to monomers, which spontaneously assembled to oligomers w hen concentrated in the absence of ethanol, Both the reconstituted hom o-oligomers were unstable, and easily dissociated to monomers, Further structural and functional characterization is necessary to elucidate if these homooligomers exist and if so, their function in vivo. (C) 19 98 Academic Press.