Effect of the C-terminal truncation on the functional cycle of chaperonin GroEL: Implication that the C-terminal region facilitates the transition from the folding-arrested to the folding-competent state

Mihoko Suzuki, Taro Ueno, Ryo Iizuka, Takahiro Miura, Tamotsu Zako, Rena Akahori, Takeo Miyake, Naonobu Shimamoto, Mutsuko Aoki, Takashi Tanii, Iwao Ohdomari, Takashi Funatsu

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To elucidate the exact role of the C-terminal region of GroEL in its functional cycle, the C-terminal 20-amino acid truncated mutant of GroEL was constructed. The steady-state ATPase rate and duration of GroES binding showed that the functional cycle of the truncated GroEL is extended by ∼2 s in comparison with that of the wild type, without interfering with the basic functions of GroEL. We have proposed a model for the functional cycle of GroEL, which consists of two rate-limiting steps of ∼3- and ∼5-s duration (Ueno, T., Taguchi, H., Tadakuma, H., Yoshida, M., and Funatsu, T. (2004) Mol. Cell 14, 423-434). According to the model, detailed kinetic studies were performed. We found that a 20-residue truncation of the C terminus extends the time until inorganic phosphate is generated and the time for arresting protein folding in the central cavity, i.e. the lifetime of the first rate-limiting step in the functional cycle, to an ∼5-s duration. These results suggest that the integrity of the C-terminal region facilitates the transition from the first to the second rate-limiting state.

Original languageEnglish
Pages (from-to)23931-23939
Number of pages9
JournalJournal of Biological Chemistry
Issue number35
Publication statusPublished - 2008 Aug 29


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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