Functional characterization of the recombinant group II chaperonin alpha from Thermoplasma acidophilum.
The functional characteristics of group II chaperonins, especially those from archaea, have not been elucidated extensively. Here, we performed a detailed functional characterization of recombinant chaperonin alpha subunits (16-mer) (Ta-cpn alpha) from the thermophilic archaea Thermoplasma acidophilum as a model protein of archaeal group II chaperonins. Recombinant Ta-cpn alpha formed an oligomeric ring structure similar to that of native protein, and displayed an ATP hydrolysis activity (optimal temperature: 60 degrees C) in the presence of either magnesium, manganese or cobalt ions. Ta-cpn alpha was able to bind refolding intermediates of Thermus MDH and GFP in the absence of ATP, and to promote the refolding of Thermus MDH at 50 degrees C in the presence of Mg2+-, Mn2+-, or Co2+-ATP. Ta-cpn alpha also prevented thermal aggregation of rhodanese and luciferase at 50 degrees C. Interestingly, Ta-cpn alpha in the presence of Mn2+ ion showed an increased hydrophobicity, which correlated with an increased efficiency in substrate protein binding. Our finding that Ta-cpn alpha chaperonin system displays folding assistance ability with ATP-dependent substrate release may provide a detailed look at the potential functional capabilities of archaeal chaperonins.
Hirai
Hidenori
H
Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori, Japan.
Noi
Kentaro
K
Hongo
Kunihiro
K
Mizobata
Tomohiro
T
Kawata
Yasushi
Y
D018833:Chaperonins / Q000737:chemistry / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008970:Molecular Weight; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013822:Thermoplasma / Q000378:metabolism*
D011994:Recombinant Proteins; D018833:Chaperonins