A Chaperone Network for the Resolubilization of Protein Aggregates: Direct Interaction of ClpB and DnaK

Schlee, Sandra; Beinker, Philipp; Akhrymuk, Alena; Reinstein, Jochen

doi:10.1016/j.jmb.2003.12.013

Cited by 73 publications

(65 citation statements)

References 41 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have seen that the DnaK system acts exclusively with ClpB and is unable to work synergistically with ClpA or ClpX. The specificity of the DnaK system for ClpB complements the results showing that ClpB and Hsp104 are only able to function with DnaK/Hsp70 from the same organism (7,36). The observation that the rate of ATP hydrolysis by the combination of ClpB and the DnaK system in the presence of substrate is greater than the sum of the separate rates provides additional support for transient interactions between the two chaperone systems and substrate.…”

Section: Discussionsupporting

confidence: 69%

“…The observation that the rate of ATP hydrolysis by the combination of ClpB and the DnaK system in the presence of substrate is greater than the sum of the separate rates provides additional support for transient interactions between the two chaperone systems and substrate. Although interactions between E. coli ClpB, DnaK and aggregated substrate have not been detected, interactions between ClpB and DnaK have been reported for the homologous chaperones from Thermus thermophilus, as have interactions of substrates with ClpB and substrates with DnaK (17,(36)(37)(38)(39).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Collaboration between the ClpB AAA+ remodeling protein and the DnaK chaperone system

Doyle

Hoskins

Wickner³

2007

Proc. Natl. Acad. Sci. U.S.A.

104

View full text Add to dashboard Cite

ClpB and Hsp104, members of the AAA؉ superfamily of proteins, protect cells from the devastating effects of protein inactivation and aggregation that arise after extreme heat stress. They exist as a hexameric ring and contain two nucleotide-binding sites per monomer. ClpB and Hsp104 are able to dissolve protein aggregates in conjunction with the DnaK/Hsp70 chaperone system, although the roles of the individual chaperones in disaggregation are not well understood. In the absence of the DnaK/Hsp70 system, ClpB and Hsp104 alone are able to perform protein remodeling when their ATPase activity is asymmetrically slowed either by providing a mixture of ATP and ATP␥S, a nonphysiological and slowly hydrolyzed ATP analog, or by inactivating one of the two nucleotide-binding domains by mutation. To gain insight into the roles of ClpB and the DnaK system in protein remodeling, we tested whether there was a further stimulation by the DnaK chaperone system under conditions that elicited remodeling activity by ClpB alone. Our results demonstrate that ClpB and the DnaK system act synergistically to remodel proteins and dissolve aggregates. The results further show that ATP is required and that both nucleotidebinding sites of ClpB must be able to hydrolyze ATP to permit functional collaboration between ClpB and the DnaK system.S evere cellular stress results in extensive protein denaturation and aggregation. To combat these effects and ensure survival, cells possess an array of molecular chaperones and proteases. Clp/Hsp100 proteins are one of the major classes of chaperones belonging to the AAAϩ superfamily (ATPases associated with various cellular activities) (1, 2). Two members of this family, Escherichia coli ClpB and its eukaryotic homolog yeast Hsp104, are essential for cell survival during extreme heat stress (3, 4) where they function to disaggregate and reactivate aggregated proteins (5, 6). In vitro ClpB and Hsp104 are able to solubilize and reactivate protein aggregates in ATP-dependent reactions in collaboration with the DnaK/Hsp70 chaperone system, comprising DnaK, DnaJ, and GrpE in prokaryotes and Hsp70, Hsp40, and GrpE-like proteins in eukaryotes (7-10). However, the roles of the two chaperone systems in disaggregation are not well understood.ClpB and Hsp104 are hexameric proteins consisting of identical protomers, with each protomer containing an N-domain and two AAAϩ domains [nucleotide-binding domain 1 and 2 (NBD-1 and NBD-2)] (Fig. 1A and ref. 11). The protomers are arranged in a ring with an axial pore (channel) similar to that observed for other Hsp100 proteins, including ClpA, ClpX, and HslU (11-15). ATP binding, which occurs at the interface of adjacent subunits, stabilizes the hexamer (11, 16). ATP binding is also required for substrate interaction with conserved residues in the pore of hexameric ClpB (17, 18). ClpB and Hsp104 possess a long coiled-coil middle domain inserted in the linear amino acid sequence of NBD-1. From single molecule reconstructions of electron microscopic images the domain seems t...

show abstract

Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Collaboration between the ClpB AAA+ remodeling protein and the DnaK chaperone system

Doyle

Hoskins

Wickner³

2007

Proc. Natl. Acad. Sci. U.S.A.

104

View full text Add to dashboard Cite

show abstract

“…Although it is conceivable that the disaggregase and refolding components of the bichaperone network function entirely independently, a physical association between the components is an appealing notion. An interaction with T. thermophilus ClpB and DnaK has been recently reported (38). Although the site of DnaK binding was not established in these studies, logic dictates that direct channeling of substrates from ClpB to DnaK would be rendered most efficient if DnaK were situated near the exit pore in the C-terminal AAAϩ domain.…”

Section: Discussionmentioning

confidence: 94%

Evidence for an Unfolding/Threading Mechanism for Protein Disaggregation by Saccharomyces cerevisiae Hsp104

Lum

Tkach

Vierling

et al. 2004

Journal of Biological Chemistry

226

236

View full text Add to dashboard Cite

show abstract

“…5b). Alternatively, it is possible that the last steps of the unfolding reaction may still be carried out by a minority of Hsp70 molecules when the terminal-misfolded species are maintained in a complex with other power-stroke chaperones such as ClpB (20) and GroEL (21) or holding chaperones such as small heat shock proteins (22).…”

Section: Passive and Active Molecular Mechanisms Of The Hsp70mentioning

confidence: 99%

Active Solubilization and Refolding of Stable Protein Aggregates By Cooperative Unfolding Action of Individual Hsp70 Chaperones

Ben‐Zvi

Rios

Dietler

et al. 2004

Journal of Biological Chemistry

100

113

View full text Add to dashboard Cite

Hsp70 is a central molecular chaperone that passively prevents protein aggregation and uses the energy of ATP hydrolysis to solubilize, translocate, and mediate the proper refolding of proteins in the cell. Yet, the molecular mechanism by which the active Hsp70 chaperone functions are achieved remains unclear. Here, we show that the bacterial Hsp70 (DnaK) can actively unfold misfolded structures in aggregated polypeptides, leading to gradual disaggregation. We found that the specific unfolding and disaggregation activities of individual DnaK molecules were optimal for large aggregates but dramatically decreased for small aggregates. The active unfolding of the smallest aggregates, leading to proper global refolding, required the cooperative action of several DnaK molecules per misfolded polypeptide. This finding suggests that the unique ATP-fueled locking/unlocking mechanism of the Hsp70 chaperones can recruit random chaperone motions to locally unfold misfolded structures and gradually disentangle stable aggregates into refoldable proteins.

show abstract

A Chaperone Network for the Resolubilization of Protein Aggregates: Direct Interaction of ClpB and DnaK

Cited by 73 publications

References 41 publications

Collaboration between the ClpB AAA+ remodeling protein and the DnaK chaperone system

Collaboration between the ClpB AAA+ remodeling protein and the DnaK chaperone system

Evidence for an Unfolding/Threading Mechanism for Protein Disaggregation by Saccharomyces cerevisiae Hsp104

Active Solubilization and Refolding of Stable Protein Aggregates By Cooperative Unfolding Action of Individual Hsp70 Chaperones

Contact Info

Product

Resources

About