Group II chaperonins of archaea and eukaryotes are distinct from group I chaperonins of bacteria. Whereas group I chaperonins require the co-chaperonin @entity22253 or @entity22253 for protein folding, no co-chaperonin has been known for group II. The protein folding mechanism of group II chaperonins is not yet clear. To understand this mechanism, we examined protein refolding by the recombinant alpha or beta-subunit chaperonin homo-oligomer (alpha16mer and beta16mer) from a hyperthermoplilic archaeum, Thermococcus strain KS-1, using a model substrate, green fluorescent protein (GFP). The alpha16mer and beta16mer captured the non-native GFP and promoted its refolding without any co-chaperonin in an @entity855 dependent manner. A non-hydrolyzable @entity855 analog, @entity860 - @entity26864 , induced the GFP refolding mediated by beta16mer but not by the alpha16mer. A mutant @entity54909 ) could capture the non-native protein but lacked the ability to refold it. Although @entity54909 suppressed @entity855 -dependent refolding of GFP mediated by alpha16mer or beta16mer, it did not affect the @entity860 - @entity26864 -dependent refolding. This indicated that the GFP refolding mediated by beta16mer with @entity860 - @entity26864 was not accessible to the @entity54909 . Gel filtration chromatography and a protease protection experiment revealed that this refolded GFP, in the presence of @entity860 - @entity26864 , was associated with beta16mer. After the completion of GFP refolding mediated by beta16mer with @entity860 - @entity26864 , addition of @entity855 induced an additional refolding of GFP. Furthermore, the beta16mer preincubated with @entity860 - @entity26864 showed the ability to capture the non-native GFP. These suggest that @entity860 - @entity26864 induced one of two chaperonin rings (cis-ring) to close and induced protein refolding in this ring, and that the other ring (trans-ring) could capture the unfolded GFP which was refolded by adding @entity855 . The present data indicate that, in the group II chaperonin of Thermococcus strain KS-1, the protein folding proceeds in its cis-ring in an @entity855 -dependent fashion without any co-chaperonin.

Archaeal group II chaperonin mediates protein folding in the cis-cavity without a detachable XXXX -like co-chaperonin.

@entity54909 :: ('6745', 'Gene') :: ['trap-alpha', 'alpha-subunit chaperonin homo-oligomer (trap-alpha'] @entity22253 :: ('3336', 'Gene') :: ['GroES', 'Cpn-10'] @entity860 :: ('MESH:D000249', 'Chemical') :: ['AMP'] @entity26864 :: ('CHEBI:16836', 'Chemical') :: ['PNP'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity22253 :: (3336,Gene) :: ['GroES']
