Key points are not available for this paper at this time.
Group II chaperonins, found in archaea and in eukaryotic cytosol, do not have a co-chaperonin corresponding to GroES. Instead, it is suggested that the helical protrusion extending from the apical domain acts as a built-in lid for the central cavity and that the opening and closing of the lid is regulated by ATP binding and hydrolysis. However, details of this conformational change remain unclear. To investigate the conformational change associated with the ATP-driven cycle, we conducted protease sensitivity analyses and tryptophan fluorescence spectroscopy of α-chaperonin from a hyperthermophilic archaeum, Thermococcus strain KS-1. In the nucleotide-free or ADP-bound state, the chaperonin, especially in the helical protrusion region, was highly sensitive to proteases. Addition of ATP and ammonium sulfate induced the transition to the relatively protease-resistant form. The fluorescence intensity of the tryptophan residue introduced at the tip of the helical protrusion was enhanced by the presence of ATP or ammonium sulfate. We conclude that ATP binding induces the conformational change from the lid-open to lid-closed form in archaeal group II chaperonin. Group II chaperonins, found in archaea and in eukaryotic cytosol, do not have a co-chaperonin corresponding to GroES. Instead, it is suggested that the helical protrusion extending from the apical domain acts as a built-in lid for the central cavity and that the opening and closing of the lid is regulated by ATP binding and hydrolysis. However, details of this conformational change remain unclear. To investigate the conformational change associated with the ATP-driven cycle, we conducted protease sensitivity analyses and tryptophan fluorescence spectroscopy of α-chaperonin from a hyperthermophilic archaeum, Thermococcus strain KS-1. In the nucleotide-free or ADP-bound state, the chaperonin, especially in the helical protrusion region, was highly sensitive to proteases. Addition of ATP and ammonium sulfate induced the transition to the relatively protease-resistant form. The fluorescence intensity of the tryptophan residue introduced at the tip of the helical protrusion was enhanced by the presence of ATP or ammonium sulfate. We conclude that ATP binding induces the conformational change from the lid-open to lid-closed form in archaeal group II chaperonin. Chaperonins, one of the principal molecular chaperones, capture non-native proteins and promote folding in vivo and in vitro in an ATP-dependent manner. They form large cylindrical complexes composed of two stacked rings of 7–9 subunits, each about 60 kDa in size. There is a large cavity in the center of the complex, where unfolded proteins may be encapsulated and undergo productive folding (1Bukau B. Horwich A.L. Cell. 1998; 92: 351-366Abstract Full Text Full Text PDF PubMed Scopus (2397) Google Scholar, 2Ranson N.A. White H.E. Saibil H.R. Biochem. J. 1998; 333: 233-242Crossref PubMed Scopus (164) Google Scholar). Based on protein sequence similarity and structural features, chaperonins are grouped into two subfamilies (3Kubota H. Hynes G. Willison K. Eur. J. Biochem. 1995; 230: 3-16Crossref PubMed Scopus (256) Google Scholar, 4Gutsche I. Essen L.O. Baumeister W. J. Mol. Biol. 1999; 293: 295-312Crossref PubMed Scopus (182) Google Scholar). Group I chaperonins are found in bacteria and eukaryotic organelles, mitochondria and chloroplasts. The Escherichia coli chaperonin, GroEL, is the most extensively characterized member of the chaperonins. GroEL facilitates protein folding with a cofactor termed GroES in an ATP-dependent manner. GroES has two functions; it acts as a lid to cap the cavity of GroEL, and then induces the release of bound substrate protein into the GroEL-GroES cavity where it can undergo folding (5Kusmierczyk A.R. Martin J. FEBS Lett. 2001; 505: 343-347Crossref PubMed Scopus (20) Google Scholar). The group II chaperonins are found in archaea (as thermosome) and in the cytosol of eukaryotic cells (as CCT or TRiC). 1The abbreviations used are: CCT, chaperonin-containing t-complex polypeptide-1; TRiC, TCP1-ring complex; T. KS-1, hyperthermophilic archaeum Thermococcus sp. strain KS-1; αWT, wild type α T. KS-1 chaperonin; αG65S, G65S mutant α T. KS-1 chaperonin; αG65C, G65C mutant α T. KS-1 chaperonin; αL265W, L265W mutant α T. KS-1 chaperonin; αG65S/L265W, G65S/L265W double mutant α T. KS-1 chaperonin; αG65C/I125T, G65C/I125T double mutant α T. KS-1 chaperonin; GFP, green fluorescent protein; DTT, dithiothreitol; native-PAGE, PAGE without SDS; PK, proteinase K; AMP-PNP, adenosine 5′-(β,γ-imino)triphosphate.1The abbreviations used are: CCT, chaperonin-containing t-complex polypeptide-1; TRiC, TCP1-ring complex; T. KS-1, hyperthermophilic archaeum Thermococcus sp. strain KS-1; αWT, wild type α T. KS-1 chaperonin; αG65S, G65S mutant α T. KS-1 chaperonin; αG65C, G65C mutant α T. KS-1 chaperonin; αL265W, L265W mutant α T. KS-1 chaperonin; αG65S/L265W, G65S/L265W double mutant α T. KS-1 chaperonin; αG65C/I125T, G65C/I125T double mutant α T. KS-1 chaperonin; GFP, green fluorescent protein; DTT, dithiothreitol; native-PAGE, PAGE without SDS; PK, proteinase K; AMP-PNP, adenosine 5′-(β,γ-imino)triphosphate. Group II chaperonins do not have a co-chaperonin corresponding to GroES. The crystal structure of the group II chaperonin from an acidothermophilic archaeum, Thermoplasma acidophilum, suggested that the function of GroES is replaced by long helical protrusions from the apical domain (6Klumpp M. Baumeister W. Essen L.O. Cell. 1997; 91: 263-270Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar, 7Ditzel L. Lowe J. Stock D. Stetter K.O. Huber H. Huber R. Steinbacher S. Cell. 1998; 93: 125-138Abstract Full Text Full Text PDF PubMed Scopus (365) Google Scholar). These protrusions are thought to function as a “built-in lid” for the central cavity. Presumably, ATP binding drives group II chaperonins from the lid-open, substrate binding conformation, into the lid-closed conformation, where substrate folds within the central cavity (6Klumpp M. Baumeister W. Essen L.O. Cell. 1997; 91: 263-270Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar, 7Ditzel L. Lowe J. Stock D. Stetter K.O. Huber H. Huber R. Steinbacher S. Cell. 1998; 93: 125-138Abstract Full Text Full Text PDF PubMed Scopus (365) Google Scholar, 8Klumpp M. Baumeister W. FEBS Lett. 1998; 430: 73-77Crossref PubMed Scopus (48) Google Scholar, 9Horwich A.L. Saibil H.R. Nat. Struct. Biol. 1998; 5: 333-336Crossref PubMed Scopus (29) Google Scholar). However, the exact relationship between the nucleotide-bound state and the conformation is still controversial in group II chaperonins. Szpikowska et al. (10Szpikowska B.K. Swiderek K.M. Sherman M.A. Mas M.T. Protein Sci. 1998; 7: 1524-1530Crossref PubMed Scopus (24) Google Scholar) reported that CCT is more resistant to trypsin digestion at the apical domain in the presence of ATP than in the absence of nucleotide and the presence of AMP-PNP, and the AMP-PNP-bound form of CCT is trypsin-sensitive as is the nucleotide-free form. On the other hand, Llorca et al. (11Llorca O. Martin-Benito J. Grantham J. Ritco-Vonsovici M. Willison K.R. Carrascosa J.L. Valpuesta J.M. EMBO J. 2001; 20: 4065-4075Crossref PubMed Scopus (115) Google Scholar) showed that the binding of AMP-PNP to CCT results in the cavity being closed off by the helical protrusions of the apical domains. Also, they showed that ATP induces an asymmetric structure; one of the rings in the conformation is similar to that of the nucleotide-free CCT, whereas the other presents a more open conformation (12Llorca O. Smyth M.G. Marco S. Carrascosa J.L. Willison K.R. Valpuesta J.M. J. Biol. Chem. 1998; 273: 10091-10094Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 13Llorca O. Smyth M.G. Carrascosa J.L. Willison K.R. Radermacher M. Steinbacher S. Valpuesta J.M. Nat. Struct. Biol. 1999; 6: 639-642Crossref PubMed Scopus (97) Google Scholar). Gutsche and colleagues (14Gutsche I. Holzinger J. Rauh N. Baumeister W. May R.P. J. Struct. Biol. 2001; 135: 139-146Crossref PubMed Scopus (32) Google Scholar) pointed out that the binding of ATP or AMP-PNP to the thermosome induces the closed conformation. Using cryo-electron microscopy and three-dimensional reconstruction, three conformational states were found in archaeal chaperonins, regardless of the presence of nucleotides; an open form, a closed form, and a bullet-shaped form with one open and one closed ring (15Schoehn G. Quaite-Randall E. Jimenez J.L. Joachimiak A. Saibil H.R. J. Mol. Biol. 2000; 296: 813-819Crossref PubMed Scopus (66) Google Scholar, 16Schoehn G. Hayes M. Cliff M. Clarke A.R. Saibil H.R. J. Mol. Biol. 2000; 301: 323-332Crossref PubMed Scopus (56) Google Scholar). The chaperonin from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1 (T. KS-1), is one of the most studied group II chaperonins (17Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 1997; 273: 635-645Crossref PubMed Scopus (74) Google Scholar, 18Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 2000; 299 (corrigendum): 1399-1400Crossref Scopus (15) Google Scholar, 19Yoshida T. Ideno A. Hiyamuta S. Yohda M. Maruyama T. Mol. Microbiol. 2001; 39: 1406-1413Crossref PubMed Google Scholar, 20Iizuka R. Yoshida T. Maruyama T. Shomura Y. Miki K. Yohda M. Biochem. Biophys. Res. Commun. 2001; 289: 1118-1124Crossref PubMed Scopus (29) Google Scholar, 21Yoshida T. Kawaguchi R. Taguchi H. Yoshida M. Yasunaga T. Wakabayashi T. Yohda M. Maruyama T. J. Mol. Biol. 2002; 315: 73-85Crossref PubMed Scopus (43) Google Scholar, 22Yoshida T. Kawaguchi R. Maruyama T. FEBS Lett. 2002; 514: 269-274Crossref PubMed Scopus (8) Google Scholar, 23Yoshida T. Ideno A. Suzuki R. Yohda M. Maruyama T. Mol. Microbiol. 2002; 44: 761-769Crossref PubMed Scopus (24) Google Scholar). T. KS-1 chaperonin is composed of two highly homologous subunits, α and β. Although the natural chaperonin isolated from T. KS-1 is a hetero-oligomer, each of the recombinant α and β subunits forms a double-ring homo-oligomer and functions as a chaperonin in vitro (17Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 1997; 273: 635-645Crossref PubMed Scopus (74) Google Scholar, 18Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 2000; 299 (corrigendum): 1399-1400Crossref Scopus (15) Google Scholar, 19Yoshida T. Ideno A. Hiyamuta S. Yohda M. Maruyama T. Mol. Microbiol. 2001; 39: 1406-1413Crossref PubMed Google Scholar). Recent experimental results using β-chaperonin and natural chaperonin suggest that the protein folding occurs within the cis-cavity (21Yoshida T. Kawaguchi R. Taguchi H. Yoshida M. Yasunaga T. Wakabayashi T. Yohda M. Maruyama T. J. Mol. Biol. 2002; 315: 73-85Crossref PubMed Scopus (43) Google Scholar). However, details of conformational changes in the protein folding cycle of group II chaperonins remain unclear. In this report, we analyzed the protease sensitivity and tryptophan fluorescence spectroscopy of T. KS-1 α-chaperonins to study the conformational changes associated with the functional ATPase cycle. In the nucleotide-free or ADP-bound state, the chaperonin was highly sensitive to proteases. The amino acid sequences of the digested fragments suggested that the proteases firstly attacked the helical protrusions, which composed the built-in lid. Addition of ATP induced the transition to the relatively protease-resistant form. The fluorescence intensity of the introduced tryptophan residue was enhanced by the addition of ATP and AMP-PNP. The findings support the notion that ATP binding induces conformational change from an open to closed state in archaeal group II chaperonin. Bacterial Strains, Plasmids, Reagents, and Buffers—The E. coli strains used in this study were DH5α for plasmid preparation and BL21(DE3) for protein expression. The plasmids pK1Eα2 and pK1Eα1–4 were used as a template for mutagenesis and for expression of αWT and αG65S, respectively (18Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 2000; 299 (corrigendum): 1399-1400Crossref Scopus (15) Google Scholar, 20Iizuka R. Yoshida T. Maruyama T. Shomura Y. Miki K. Yohda M. Biochem. Biophys. Res. Commun. 2001; 289: 1118-1124Crossref PubMed Scopus (29) Google Scholar). The restriction endonucleases were products of Takara (Kyoto, Japan). Nucleotides and thermolysin were purchased from Wako Chemicals (Tokyo, Japan). Other reagents or enzymes used were of the biochemical research grade. The assay buffer used in this work is TNM buffer (50 mm Tris-HCl, pH 7.5, 100 mm NaCl, and 25 mm MgCl2) or TKM buffer (50 mm Tris-HCl, pH 7.5, 100 mm KCl, and 25 mm MgCl2), with exceptions specially described. Site-directed Mutagenesis—The tryptophan mutants were constructed using a QuikChange site-directed mutagenesis kit (Strata-gene, CA). The 30-nucleotide primers 5′-CCAGCCCGGACCAGTGGATGAGCTTCCTTG-3′ and 5′-CAAGGAAGCTCATCCACTGGTCCGGGCTGG-3′ (mutated nucleotides are underlined), containing a cleavage site of FokI, were used for the codon substitution, CTC to TGG (Leu to Trp) on pK1Eα2 or pK1Eα1–4. The mutants were selected by FokI digestion and were confirmed by DNA sequencing. DNA manipulation was carried out as described by Sambrook et al. (24Sambrook J. Fritsch E.F. Maniatis T. Molecular Cloning: A Laboratory Manual, 2nd. Ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY1989Google Scholar). Purification of Chaperonins—The α-chaperonins of wild and mutants were expressed in E. coli BL21(DE3) cells transformed with expression plasmids. They were cultured aerobically in 2xYT medium (16 g of tryptone, 10 g of yeast extract, and 5 g of NaCl per liter) containing 75 μg/ml kanamycin. The harvested cells were suspended in 50 mm Tris-HCl, pH 7.5, and disrupted by sonication. The suspension of disrupted cells was centrifuged at 25,000 g for at and and were to the to 25 and The was then to at for and proteins were by The was to a with buffer A (50 mm Tris-HCl, pH 7.5, and 25 mm MgCl2) containing and mm were with a of mm NaCl in the containing the chaperonins were and and by The proteins were an with buffer A and with a of mm The containing α-chaperonins were a with buffer A containing mm chaperonins were by with to and at for chaperonins were to be nucleotide-free by the The proteins were with acid and then centrifuged to of the were to a mm with mm pH containing The was with an at Japan). of α and The α-chaperonin (50 or was with or without nucleotide a of at for 5 being digestion was carried out with thermolysin or proteinase at for 10 or 5 of the was using acid and on for more than 5 The was centrifuged and to a with protein by was to and a The was with The were and analyzed with a fluorescence of tryptophan mutants were at with a Japan). The was at and was from to for and for was with or without nucleotide for 5 at and the was the were the of were analyzed by on or PubMed Scopus Google Scholar) or on without were with Protein were using a Protein with as the Biochem. PubMed Scopus Google Scholar). The of ATP and Protein by structural changes of chaperonin in the protein folding cycle are by ATP binding and hydrolysis. is for ATP PubMed Scopus Google Scholar, I. O. Baumeister W. J. Mol. Biol. 2000; PubMed Scopus Google Scholar). The of ATP by αWT was highly on the presence of is replaced by the ATPase of αWT by a of about not the protein folding of αWT in the absence of as in the not of and release of which are for of GFP, are in the absence of we the chaperonin conformation to be in the state using in and the analyses of αWT and αWT was to thermolysin digestion with or without nucleotides in the TNM and TKM buffer In the presence of ATP or AMP-PNP, a of αWT was relatively and of about 60 α of the presence of In were in the absence of nucleotide or the presence of the αWT digested with thermolysin structure and was to capture not ATP-dependent folding not These results are with the findings for CCT (10Szpikowska B.K. Swiderek K.M. Sherman M.A. Mas M.T. Protein Sci. 1998; 7: 1524-1530Crossref PubMed Scopus (24) Google Scholar). results were in the using proteinase In the presence of ATP was not in the chaperonin from protease with the digestion by thermolysin A and We that the is by the of protease of The digestion have in the state the ATP of αWT and induced by of sulfate αWT and were with or without mm of the nucleotides AMP-PNP, and at for 5 and then thermolysin was to the chaperonin in TNM buffer containing ammonium sulfate. The are described and molecular and ammonium form of and without addition of and with and with and with was with or without mm ATP at for 5 and then thermolysin was to the chaperonin in TNM buffer without or with and ammonium The are described and molecular without addition of with with ammonium with ammonium sulfate and with with sulfate and with ammonium and with ammonium and the protease digestion were using and The mutant is in the state of nucleotide and In this the of is to be to the absence of ATP-dependent conformational change R. Yoshida T. Maruyama T. Shomura Y. Miki K. Yohda M. Biochem. Biophys. Res. Commun. 2001; 289: 1118-1124Crossref PubMed Scopus (29) Google Scholar). fragments of αWT were to amino acid to the of cleavage and a of were by digestion in the helical is thought that was proteinase into the central cavity on the crystal structure of T. KS-1 chaperonin. T. R. T. M. and K. in The to is to the that it is the helical protrusion in the apical domain was the most to in the the changes in protease sensitivity by ATP and AMP-PNP be to a conformational change of the helical of α fragments on amino acid in a we have the crystal structure of the mutant αG65C/I125T, T. R. T. M. and K. in which the as (18Yoshida T. Yohda M. Iida T. Maruyama T. Taguchi H. Yazaki K. Ohta T. Odaka M. Endo I. Kagawa Y. J. Mol. Biol. 2000; 299 (corrigendum): 1399-1400Crossref Scopus (15) Google Scholar, 20Iizuka R. Yoshida T. Maruyama T. Shomura Y. Miki K. Yohda M. Biochem. Biophys. Res. Commun. 2001; 289: 1118-1124Crossref PubMed Scopus (29) Google Scholar). this mutant an to the non-native proteins in the presence of the crystal structure in ammonium sulfate that it the closed conformation, with the helical protrusions in rings the center of the cavity. the protease digestion was in the presence of ammonium sulfate. thermolysin and proteinase were in the presence of a of ammonium sulfate not the wild type and were highly resistant to cleavage of the nucleotides was that sulfate has the as ammonium ammonium not A study suggested that Thermoplasma chaperonin the closed conformation in the presence of a of sulfate I. Holzinger J. M. H. Baumeister W. May R.P. Biol. 2000; Full Text Full Text PDF PubMed Scopus (43) Google Scholar). we that a of sulfate induced the conformational change of wild type and mutant proteins to the protease-resistant form, the closed conformation. with ATP the of the helical protrusion the functional cycle we constructed and The residue for with is at the tip of the helical T. R. T. M. and K. in The fluorescence of α-chaperonin was to the of tryptophan not by the fluorescence of the a change in the the tip of the helical protrusion be mutants capture and was to the of in an ATP-dependent the that the was than that of showed that a protease-resistant conformation on binding ATP not These results that has the to undergo the conformational changes as similar functional and structural to not and the fluorescence of The addition of ATP a large of tryptophan fluorescence intensity in Although the changes to the were to be a change in the associated with The fluorescence change in induced by AMP-PNP in TKM buffer was than that in TNM with the of protease sensitivity in the presence of AMP-PNP with and without On the other hand, change was induced by the addition of of Also, the presence of ammonium sulfate in a of fluorescence and the fluorescence of ATPase was in the TNM the fluorescence intensity of in the presence of ATP and AMP-PNP. The of AMP-PNP was in the presence of Although the fluorescence intensity of was by the of the change was than that for was the for αL265W, the presence of ammonium sulfate enhanced the fluorescence intensity of and of at without ammonium ammonium sulfate and with ammonium ammonium sulfate and without ammonium ammonium sulfate and with ammonium ammonium sulfate and in a of the of T. KS-1 α protease digestion and tryptophan fluorescence the structural of archaeal group II chaperonins. ATP induces a structural change to αWT and of In the nucleotide-free or ADP-bound state, the chaperonin was highly sensitive to proteases. Addition of ATP induced a change to the relatively protease-resistant form and The fluorescence intensity of was enhanced by the addition of ATP it is that α-chaperonin a large conformational change in the presence of and ATP and that the of ATP is for this The amino acid sequences of the digested fragments suggested that the proteases attacked the helical protrusion region, which the built-in lid that this is in the nucleotide-free and ADP-bound state, and ATP or AMP-PNP binding induces a transition to a Based on the the change of tryptophan fluorescence and the crystal T. R. T. M. and K. in we that the conformational change induced by binding ATP about the of built-in which be for protein was that the conformation of CCT bound to and in the presence of AMP-PNP is similar to that of the thermosome structure (11Llorca O. Martin-Benito J. Grantham J. Ritco-Vonsovici M. Willison K.R. Carrascosa J.L. Valpuesta J.M. EMBO J. 2001; 20: 4065-4075Crossref PubMed Scopus (115) Google Scholar). In not conformational The of protein folding by the mutant be by the of conformational change in the ATP cycle. sulfate αWT and in a state highly homologous to that of αWT bound to Gutsche et al. I. Holzinger J. M. H. Baumeister W. May R.P. Biol. 2000; Full Text Full Text PDF PubMed Scopus (43) Google Scholar) pointed out that ammonium sulfate the closed conformation, on a Although mutants are in the lid-open state, the crystal structure of the mutant α-chaperonin was to be a closed form. The be by the that the buffer a of ammonium sulfate. T. R. T. M. and K. in the in the nucleotide-free state and the ADP-bound state are the or similar to each is with results of microscopy and that the binding of not a change in structure group II chaperonins (12Llorca O. Smyth M.G. Marco S. Carrascosa J.L. Willison K.R. Valpuesta J.M. J. Biol. Chem. 1998; 273: 10091-10094Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 13Llorca O. Smyth M.G. Carrascosa J.L. Willison K.R. Radermacher M. Steinbacher S. Valpuesta J.M. Nat. Struct. Biol. 1999; 6: 639-642Crossref PubMed Scopus (97) Google Scholar, I. Holzinger J. Rauh N. Baumeister W. May R.P. J. Struct. Biol. 2001; 135: 139-146Crossref PubMed Scopus (32) Google Scholar, I. Holzinger J. M. H. Baumeister W. May R.P. Biol. 2000; Full Text Full Text PDF PubMed Scopus (43) Google Scholar). et al. R. G. S. 1997; PubMed Scopus Google Scholar) pointed out that are large between corresponding to the state of transition of ATP and in and is a for the conformational change to αWT induced by ATP binding and on the is thought that αWT is in a lid-closed state, which results in the of protein binding with the non-native protein and from the it be that the binding of ATP to to the conformation with the built-in lid Gutsche et al. (14Gutsche I. Holzinger J. Rauh N. Baumeister W. May R.P. J. Struct. Biol. 2001; 135: 139-146Crossref PubMed Scopus (32) Google Scholar) suggested that the of the thermosome with ATP is at a and that the thermosome be an open similar to GroEL in the The fluorescence intensity of ATP and AMP-PNP were in TNM Although the for the is not the form, may the lid-closed form. this is the the that the conformational changes this state, at is the of the ADP-bound form are similar to that of the nucleotide-free form, are to be the is thought that the by ATP α-chaperonin to to the open conformation. et al. D. S. J. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar) have that the lid of CCT is induced not by the binding by the of results that conformational change occurs in the presence of AMP-PNP. They that the between results and using archaeal chaperonins results from ATP of the AMP-PNP. We have found that the AMP-PNP and used in this study were with than and of the conformational change not be by the ATP it the where the of ATP was The be by the structural between CCT and archaeal chaperonins.
Iizuka et al. (Sat,) studied this question.