Journal Article

Adaptation of a hyperthermophilic group II chaperonin to relatively moderate temperatures

Taro Kanzaki, Shuzo Ushioku, Ayumi Nakagawa, Toshihiko Oka, Kazunobu Takahashi, Takashi Nakamura, Kunihiro Kuwajima, Akihiko Yamagishi and Masafumi Yohda

in Protein Engineering, Design and Selection

Volume 23, issue 5, pages 393-402
Published in print May 2010 | ISSN: 1741-0126
Published online February 2010 | e-ISSN: 1741-0134 | DOI:
Adaptation of a hyperthermophilic group II chaperonin to relatively moderate temperatures

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Group II chaperonins exist in archaea and the eukaryotic cytosol, and mediate protein folding in an ATP-dependent manner. We have been studying the reaction mechanism of group II chaperonins using α chaperonin, the recombinant chaperonin α subunit homo-oligomer from a hyperthermophilic archaeon, Thermococcus sp. strain KS-1 (T. KS-1). Although the high stability and activity of T. KS-1 α chaperonin provided advantages for our study, its high thermophilicity caused the difficulty in using various analytical methods. To resolve this problem, we tried to adapt T. KS-1 α chaperonin to moderate temperatures by mutations. The comparison of amino acid sequences between 26 thermophilic and 17 mesophilic chaperonins showed that three amino acid replacements are likely responsible for the difference of their optimal temperatures. We introduced three single mutations and also their double combinations into T. KS-1 α chaperonin. Among them, K323R single mutant exhibited the improvements of the folding activity and the ATP-dependent conformational change ability at lower temperatures, such as 50°C and 40°C. Since K323 may secure helix 12 in the closed conformation by interacting with D198, the replacement of Lys to Arg likely induced the higher mobility of the built-in lid, resulting in the higher activity at relatively low temperatures.

Keywords: cold adaptation; group II chaperonin; hyperthermophilic archaeon; protein folding; small angle X-ray scattering

Journal Article.  5965 words.  Illustrated.

Subjects: Proteins

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