Characterization of archaeal group II chaperonin-ADP-metal fluoride complexes: implications that group II chaperonins operate as a "two-stroke engine".
Group II chaperonins, found in Archaea and in the eukaryotic cytosol, act independently of a cofactor corresponding to GroES of group I chaperonins. Instead, the helical protrusion at the tip of the apical domain forms a built-in lid of the central cavity. Although many studies on the lid's conformation have been carried out, the conformation in each step of the ATPase cycle remains obscure. To clarify this issue, we examined the effects of ADP-aluminum fluoride (AlFx) and ADP-beryllium fluoride (BeFx) complexes on alpha-chaperonin from the hyperthermophilic archaeum, Thermococcus sp. strain KS-1. Biochemical assays, electron microscopic observations, and small angle x-ray scattering measurements demonstrate that alpha-chaperonin incubated with ADP and BeFx exists in an asymmetric conformation; one ring is open, and the other is closed. The result indicates that alpha-chaperonin also shares the inherent functional asymmetry of bacterial and eukaryotic cytosolic chaperonins. Most interestingly, addition of ADP and BeFx induced alpha-chaperonin to encapsulate unfolded proteins in the closed ring but did not trigger their folding. Moreover, alpha-chaperonin incubated with ATP and AlFx or BeFx adopted a symmetric closed conformation, and its functional turnover was inhibited. These forms are supposed to be intermediates during the reaction cycle of group II chaperonins.
Iizuka
Ryo
R
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
Yoshida
Takao
T
Ishii
Noriyuki
N
Zako
Tamotsu
T
Takahashi
Kazunobu
K
Maki
Kosuke
K
Inobe
Tomonao
T
Kuwajima
Kunihiro
K
Yohda
Masafumi
M
D000244:Adenosine Diphosphate / Q000737:chemistry; D000251:Adenosine Triphosphatases / Q000737:chemistry; D017607:Aluminum Compounds / Q000737:chemistry; D001105:Archaea / Q000378:metabolism*; D019843:Archaeal Proteins / Q000737:chemistry; D001608:Beryllium / Q000737:chemistry; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins / Q000737:chemistry*; D003600:Cytosol / Q000378:metabolism; D005459:Fluorides / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000737:chemistry; D008854:Microscopy, Electron; D008954:Models, Biological; D009711:Nucleotides / Q000737:chemistry; D010447:Peptide Hydrolases / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013696:Temperature; D019712:Thermococcus / Q000378:metabolism*; D014364:Tryptophan / Q000737:chemistry; D014965:X-Rays
D017607:Aluminum Compounds; D019843:Archaeal Proteins; D009711:Nucleotides; D049452:Green Fluorescent Proteins; C035982:beryllium fluoride; D000244:Adenosine Diphosphate; D014364:Tryptophan; D010447:Peptide Hydrolases; D000251:Adenosine Triphosphatases; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins; D001608:Beryllium; D005459:Fluorides; C032311:aluminum fluoride