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.
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 approximately 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 approximately 3- and approximately 5-s duration (Ueno, T., Taguchi, H., Tadakuma, H., Yoshida, M., and Funatsu, T. (2004) Mol. Cell 14, 423-434 g). 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 approximately 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.
Suzuki
Mihoko
M
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Ueno
Taro
T
Iizuka
Ryo
R
Miura
Takahiro
T
Zako
Tamotsu
T
Akahori
Rena
R
Miyake
Takeo
T
Shimamoto
Naonobu
N
Aoki
Mutsuko
M
Tanii
Takashi
T
Ohdomari
Iwao
I
Funatsu
Takashi
T
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D018834:Chaperonin 60 / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D008956:Models, Chemical; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D017384:Sequence Deletion; D013997:Time Factors
D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases