Symmetric Complexes of GroE Chaperonins as Part of the Functional Cycle

Schmidt, Marion; Rutkat, Kerstin; Rachel, Reinhard; Pfeifer, Günter; Jaenicke, Rainer; Viitanen, Paul V.; Lorimer, George H.; Büchner, Johannes

doi:10.1126/science.7913554

Cited by 196 publications

(163 citation statements)

References 30 publications

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“…If so, there should be a cone-like complex, made up from a heptamer of cpn60s and a heptamer of cpn 10 homologs, as one of intermediates in the catalytic cycle of the mitochondrial chaperonin. Also the symmetrical complex of E. coli chaperonin [22][23][24] in which rings of [GroES]7 are bound to both ends of [GroEL]14 can be related to the split reported here. This symmetrical complex has been proposed to be one of the intermediates in the chaperonin catalytic cycle [7].…”

Section: Implication Of the Equatorial Splitmentioning

confidence: 99%

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺

et al. 1995

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Holo-chaperonin molecule from Thermus thermophiIlls is a bullet-shaped particle whose cylinder part and round top are composed of two stacked rings of the cpn60 heptamer and a single ring of the cpnl0 heptamer, respectively. We found that it splits at the plane between two cpn60 rings into two halves under physiological conditions, that is, in the presence of ATP (but not AMP-PNP, ADP) + K + (but not Na +) at 60°C. This equatorial split could be functionally important although it has not been considered in any current mechanistic model of chaperonin functioning.

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Section: Implication Of the Equatorial Splitmentioning

confidence: 99%

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺

et al. 1995

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“…Each monomer of GroES has a nominal molecular weight of 10 kDa [2], and the GroES is normally found in an oligomeric configuration of seven subunits [2,13]. Although no specific functions have been identified with the GroES heptamer alone, it has been firmly established with both electron microscopy (EM) and biochemical methods that, in the presence of ATP or ADP, the GroES heptamer can form a stable complex with the GroEL tetradecamer [5,8,[18][19][20]. Upon the binding of GroES, the rate of ATP hydrolysis of GroEL is strongly affected [4,6,7,9,12,21], but the mechanism has not been well understood [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

et al. 1996

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Using atomic force microscopy (AFM) in aqueous solution, we show that the surface structure of the oligomeric GroES can be obtained up to 10 A resolution. The seven subunits of the heptamer were well resolved without image averaging. The overall dimension of the GroES heptamer was 8.4+0.4 nm in diameter and 3.0+0.3 nm high. However, the AFM images further suggest that there is a central protrusion of 0.8+0.2 nm high and 4.5+0.4 nm in diameter on one side of GroES which displays a profound seven-fold symmetry. It was found that GroEL could not bind to the adsorbed GroES in the presence of AMP-PNP and Mg 2+, suggesting that the side of GroES with the central protrusion faces away from the GroEL lumen, because only one side of GroES was observed under these conditions. Based on the results from both electron and atomic force microscopy, a surface model for the GroES is proposed.Key words: Atomic force microscopy; GroES; GroEL; Resolution subunits were not discernible [18]. Because of the variable conformations observed by EM, it was even suggested that GroES could have a flexible structure or a symmetry other than the seven-fold [18]. Since the atomic force microscopy (AFM) has been shown to be capable of obtaining high resolution surface structures of several oligomeric bacterial proteins (for recent reviews, see [24][25][26]), we have applied this method to determine the surface structure of GroES under aqueous solutions. We show that the subunit structure can be clearly resolved in the AFM images without image processing/averaging. Surface structures beyond the subunits were also resolved, demonstrating a surface resolution of 10 A or so, which is much higher than that from EM images. In combination with the results from EM, a model for the GroES is also proposed. Materials and methods

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“…A control in the absence of rhodanese was performed by processing symmetric complexes generated by incubating GroEL and GroES with AMP-PNP (5' -adenylylimido-diphosphate), a non-hydrolyzable analog of ATP, which is known to generate homogeneous populations of symmetric complexes [15,21]. This system has the advantage that no protein (apart from GroEL and GroES) is present in the solution, and therefore no unfolded substrate is bound to the symmetric complexes.…”

Section: Electron Microscopy and Image Processing Of Symmetricmentioning

confidence: 99%

“…Fax: (34) (1) 5854506. E-mail: jmv@samba.cnb.uam.es neously capping both ends of the GroEL double ring [13][14][15]. Although the functional significance of the symmetric complexes is still a matter of debate, biochemical and biophysical evidence is mounting that symmetric complexes form part of the protein folding cycle [16--19].…”

Section: Introductionmentioning

confidence: 99%

Symmetric GroEL‐GroES complexes can contain substrate simultaneously in both GroEL rings

et al. 1997

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Incubation of rhodanese with hche aperonins GroEL and GroES (1:2 GroEL 14 : GroES 7 molar ratio) under functional and steady state conditions for ATP leads to the formation of a high proportion of rhodanese-bound symmetric complexes (GroEL t4(GroES7 )2), as revealed by native electrophoresis. Aliquots of such samples were observed under the electron microscope, and the symmetric particles were classified using neuronal networks and multivariate statistical analysis. Three different populations of symmetric particles were obtained which contained substrate in none, one or both GroEL cavities, respectively. The presence of substrate in the symmetric complexes under functional conditions supports their role as active intermediates in the protein folding cycle. These results also suggest that symmetric GroEL-GroES complexes can use both rings simultaneously for folding, probably increasing the efficiency of the reaction.

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Symmetric Complexes of GroE Chaperonins as Part of the Functional Cycle

Cited by 196 publications

References 30 publications

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

Symmetric GroEL‐GroES complexes can contain substrate simultaneously in both GroEL rings

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Symmetric Complexes of GroE Chaperonins as Part of the Functional Cycle

Cited by 196 publications

References 30 publications

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K+

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K+

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

Symmetric GroEL‐GroES complexes can contain substrate simultaneously in both GroEL rings

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Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺

Equatorial split of holo‐chaperonin from Thermus thermophilus by ATP and K⁺