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

摘要

The a and beta subunits of group II chaperonin from a hyperthermophilic archaeum,Thermococcus strain KS-1,were produced in Escherichia coli.Thermococcus KS-1 a and (3 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 a and beta subunits were able to form homo-hexadecamers in the presence of Mg~(2+).In the absence of ATP,the a and p 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 deg C.In the presence of ATP,the a and beta homo-hexadecamers facilitated the refolding of LeuDH and MDH.The a homo-hexadecamer showed greater complex stability and greater ability to facilitate the refolding of enzymes than the beta homo-hexadecamer.On the other hand,both the a and P 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.