MgATP binding to the nucleotide‐binding domains of the eukaryotic cytoplasmic chaperonin induces conformational changes in the putative substrate‐binding domains

Szpikowska, B K; Swiderek, Kristine M.; Sherman, Mark A.; Mas, Maria T.

doi:10.1002/pro.5560070705

Cited by 29 publications

(19 citation statements)

References 31 publications

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“…Intriguingly, the ␣WT complex digested with thermolysin retained its quaternary structure and was able to capture denatured GFP but did not exhibit ATP-dependent folding activity (data not shown). These results are fully consistent with the previous findings for CCT (10). Similar results were obtained in the experiments using proteinase K (Fig.…”

Section: Resultssupporting

confidence: 93%

“…However, the exact relationship between the nucleotide-bound state and the conformation is still controversial in group II chaperonins. Szpikowska et al (10) 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 (11) showed that the binding of AMP-PNP to CCT results in the cavity being closed off by the helical protrusions of the apical domains.…”

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confidence: 99%

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ATP Binding Is Critical for the Conformational Change from an Open to Closed State in Archaeal Group II Chaperonin

Iizuka

Yoshida

Shomura

et al. 2003

Journal of Biological Chemistry

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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 ␣-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 (1, 2). Based on protein sequence similarity and structural features, chaperonins are grouped into two subfamilies (3, 4). 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 (5).The group II chaperonins are found in archaea (as thermosome) and in the cytosol of eukaryotic cells (as CCT or TRiC). 1Group 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 (6, 7). 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 (6 -9). However, the exact relationship between the nucleotide-bound state and the conformation is still controversial in group II chaperonins. Szpikowska et al. (10) reported that CCT is more resistant to tryp...

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Section: Resultssupporting

confidence: 93%

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confidence: 99%

ATP Binding Is Critical for the Conformational Change from an Open to Closed State in Archaeal Group II Chaperonin

Iizuka

Yoshida

Shomura

et al. 2003

Journal of Biological Chemistry

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“…Addition of ATP induces formation of the closed lid, which confines the substrate in the central cavity. Experiments with nonhydrolyzable analogs of ATP indicate that ATP binding alone does not promote closure of the lid [11,39]. Nevertheless, these non-hydrolyzable nucleotides do induce a conformational change in TRiC, which is observed by tryptophan fluorescence [40], which might, in turn, affect the conformation of the bound substrate (Figure 3b).…”

Section: Nucleotide-induced Conformational Changes In Tricmentioning

confidence: 99%

Mechanism of the eukaryotic chaperonin: protein folding in the chamber of secrets

Spiess

Meyer

Reißmann

et al. 2004

Trends in Cell Biology

345

327

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Chaperonins are key components of the cellular chaperone machinery. These large, cylindrical complexes contain a central cavity that binds to unfolded polypeptides and sequesters them from the cellular environment. Substrate folding then occurs in this central cavity in an ATP-dependent manner. The eukaryotic chaperonin TCP-1 ring complex (TRiC, also called CCT) is indispensable for cell survival because the folding of an essential subset of cytosolic proteins requires TRiC, and this function cannot be substituted by other chaperones. This specificity indicates that TRiC has evolved structural and mechanistic features that distinguish it from other chaperones. Although knowledge of this unique complex is in its infancy, we review recent advances that open the way to understanding the secrets of its folding chamber.Protein misfolding has been implicated in several human diseases that have both systemic and neurological implications, including 'conformational diseases' such as Huntington's and Parkinson's that are characterized by the accumulation of toxic protein aggregates [1]. Although small proteins with simple chain topologies can fold spontaneously, the vast majority of cellular proteins is unable to reach its native state without the assistance of elaborate cellular machinery composed of proteins known as molecular chaperones (for review, see Refs [1-4]). A complete understanding of chaperone-assisted protein folding in the cell would be an intellectual tour de force that might, eventually, lead to effective treatments for these diseases.In the cell, protein folding faces additional challenges compared with the refolding of proteins in solution [1,2,4]. For example, in vivo, the linear polypeptide chain emerges vectorially into the cytosol during synthesis on ribosomes. Because the information for the native state is encoded by the entire amino acid sequence, the nascent polypeptide chain is unable to fold stably until fully synthesized, but it exposes hydrophobic sequences into the crowded cellular milieu [4]. Details of how newly translated proteins navigate toward a final, fully functional, folded structure in vivo are not entirely understood, but it is clear that exposed hydrophobic surfaces can contribute to misfolding and aggregation. Accordingly, all cellular compartments contain many structurally and functionally distinct classes of chaperones that vary in size and complexity, ranging from those that bind only to misfolded polypeptides and prevent their aggregation to those that recognize specific classes of proteins and facilitate their folding to the native state in an energy-dependent manner [1][2][3]. In cells, these different classes of chaperones work together to form elaborate, cooperative networks that ensure the correct folding of newly translated proteins; they also ensure that potentially damaging misfolded polypeptides are cleared from the cell [5].

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“…2a, left gel). Notably, cleavage occurred at a position in the Cpn lid equivalent to that cleaved in TRiC subunits 27 . Incubation with ATP, but not ADP, triggers lid closure, resulting in protection of the lid segments (Fig.…”

Section: The Lid Couples Atp Hydrolysis To Substrate Foldingmentioning

confidence: 99%

Essential function of the built-in lid in the allosteric regulation of eukaryotic and archaeal chaperonins

Reißmann

Parnot

Booth

et al. 2007

Nat Struct Mol Biol

165

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Chaperonins are allosteric double-ring ATPases that mediate cellular protein folding. ATP binding and hydrolysis control opening and closing of the central chaperonin chamber, which transiently provides a protected environment for protein folding. During evolution, two strategies to close the chaperonin chamber have emerged. Archaeal and eukaryotic group II chaperonins contain a builtin lid, whereas bacterial chaperonins use a ring-shaped cofactor as a detachable lid. Here we show that the built-in lid is an allosteric regulator of group II chaperonins, which helps synchronize the subunits within one ring and, to our surprise, also influences inter-ring communication. The lid is dispensable for substrate binding and ATP hydrolysis, but is required for productive substrate folding. These regulatory functions of the lid may serve to allow the symmetrical chaperonins to function as 'two-stroke' motors and may also provide a timer for substrate encapsulation within the closed chamber.Chaperonins are ubiquitous and essential mediators of cellular protein folding that consist of 14-18 subunits arranged in two stacked rings [1][2][3][4] . Each ring encompasses a central chamber that accommodates non-native polypeptides. All chaperonins share a similar subunit architecture, consisting of three distinct domains: an ATP-binding equatorial domain, a distal apical domain harboring the polypeptide-binding sites and an intermediate hinge domain. A key feature of chaperonins is their ability to close their chamber and encapsulate the bound substrate, thus providing a protected environment for protein folding. Opening and closing of the folding chamber is controlled by a conformational cycle driven by ATP binding and hydrolysis. Despite overall structural similarities, there are substantial differences between the eubacterial chaperonins, such as GroEL from E. coli [2][3][4][5] , and the

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MgATP binding to the nucleotide‐binding domains of the eukaryotic cytoplasmic chaperonin induces conformational changes in the putative substrate‐binding domains

Cited by 29 publications

References 31 publications

ATP Binding Is Critical for the Conformational Change from an Open to Closed State in Archaeal Group II Chaperonin

ATP Binding Is Critical for the Conformational Change from an Open to Closed State in Archaeal Group II Chaperonin

Mechanism of the eukaryotic chaperonin: protein folding in the chamber of secrets

Essential function of the built-in lid in the allosteric regulation of eukaryotic and archaeal chaperonins

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