Sequential action of ATP-dependent subunit conformational change and interaction between helical protrusions in the closure of the built-in lid of group II chaperonins.
ATP drives the conformational change of the group II chaperonin from the open lid substrate-binding conformation to the closed lid conformation to encapsulate an unfolded protein in the central cavity. The detailed mechanism of this conformational change remains unknown. To elucidate the intra-ring cooperative action of subunits for the conformational change, we constructed Thermococcus chaperonin complexes containing mutant subunits in an ordered manner and examined their folding and conformational change abilities. Chaperonin complexes containing wild-type subunits and mutant subunits with impaired ATP-dependent conformational change ability or ATP hydrolysis activity, one by one, exhibited high protein refolding ability. The effects of the mutant subunits correlate with the number and order in the ring. In contrast, the use of a mutant lacking helical protrusion severely affected the function. Interestingly, these mutant chaperonin complexes also exhibited ATP-dependent conformational changes as demonstrated by small angle x-ray scattering, protease digestion, and changes in fluorescence of the fluorophore attached to the tip of the helical protrusion. However, their conformational change is likely to be transient. They captured denatured proteins even in the presence of ATP, whereas addition of ATP impaired the ability of the wild-type chaperonin to protect citrate synthase from thermal aggregation. These results suggest that ATP binding/hydrolysis causes the independent conformational change of the subunit, and further conformational change for the complete closure of the lid is induced and stabilized by the interaction between helical protrusions.
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Taro
T
Kanzaki
Ryo
R
Iizuka
Kazunobu
K
Takahashi
Kosuke
K
Maki
Rie
R
Masuda
Muhamad
M
Sahlan
Hugo
H
Yébenes
José M
JM
Valpuesta
Toshihiko
T
Oka
Masahiro
M
Furutani
Noriyuki
N
Ishii
Kunihiro
K
Kuwajima
Masafumi
M
Yohda
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry*; D018833:Chaperonins / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006358:Hot Temperature; D006868:Hydrolysis; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D010447:Peptide Hydrolases / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D019712:Thermococcus / Q000378:metabolism*
D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D010447:Peptide Hydrolases; D000251:Adenosine Triphosphatases; D018833:Chaperonins