Refolding of proteins by hexadecamers and monomers of the α and β subunits of group II chaperonin from the hyperthermophilic archaeum Thermococcus strain KS-1

Abstract

The α and β subunits of group II chaperonin from a hyperthermophilic archaeum, Thermococcus strain KS-1, were produced in Escherichia coli. Thermococcus KS-1 α and β chaperonins were purified from a crude cell extract by heat treatment and subsequent chromatographic purification in the presence and absence of Mg 2+ to produce hexadecameric and monomeric form, respectively. The monomeric α and β subunits were able to form homo-hexadecamers in the presence of Mg 2+. In the absence of ATP, the α and β homo-hexadecamers arrested the refolding of guanidine hydrochloride-denatured Bacillus stearothermophilus leucine dehydrogenase (LeuDH) and Thermus flavus malate dehydrogenase (MDH), which were released by the addition of ATP at 50–65 °C. In the presence of ATP, the α and β homo-hexadecamers facilitated the refolding of LeuDH and MDH. The α homo-hexadecamer showed greater complex stability and greater ability to facilitate the refolding of enzymes than the β homo-hexadecamer. On the other hand, both the α and β monomers facilitated the refolding of the proteins in the absence of ATP. Thermococcus KS-1 chaperonin homo-hexadecamers and monomers could both therefore be used as molecular tools in biotechnology.