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- Title
Functional Characterization of the Recombinant Group II Chaperonin α from Thermoplasma acidophilum.
- Authors
Hirai, Hidenori; Noi, Kentaro; Hongo, Kunihiro; Mizobata, Tomohiro; Kawata, Yasushi
- Abstract
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 α subunits (16-mer) (Ta-cpn α) from the thermophilic archaea Thermoplasma acidophilum as a model protein of archaeal group II chaperonins. Recombinant Ta-cpn α formed an oligomeric ring structure similar to that of native protein, and displayed an ATP hydrolysis activity (optimal temperature: 60°C) in the presence of either magnesium, manganese or cobalt ions. Ta-cpn α 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°C in the presence of Mg2+-, Mn2+-, or Co2+-ATP. Ta-cpn α also prevented thermal aggregation of rhodanese and luciferase at 50°C. Interestingly, Ta-cpn α 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 α chaperonin system displays folding assistance ability with ATP-dependent substrate release may provide a detailed look at the potential functional capabilities of archaeal chaperonins.
- Subjects
MOLECULAR chaperones; ARCHAEBACTERIA; PROTEINS; METAL ions; PROTEIN binding
- Publication
Journal of Biochemistry, 2008, Vol 143, Issue 4, p505
- ISSN
0021-924X
- Publication type
Article
- DOI
10.1093/jb/mvm241