Hsp90 Quaternary Structures and the Chaperone Cycle: Highly Flexible Dimeric and Oligomeric Structures and Their Regulation by Co-Chaperones

2018 ◽  
Vol 16 (1) ◽  
pp. 5-11
Author(s):  
Eléonore Lepvrier ◽  
Daniel Thomas ◽  
Cyrille Garnier
Keyword(s):  
Conformational Changes ◽  
Client Protein ◽  
Key Players ◽  
Hsp90 Activity ◽  
Hsp90 Chaperone ◽  
Client Proteins ◽  
Quaternary Structures ◽  
Chaperone Interactions ◽  
High Flexibility ◽  
Future Work

Proposed models of the function of Hsp90 are characterised by high flexibility of the dimeric state and conformational changes regulated by both nucleotide binding and hydrolysis, and by co-chaperone interactions. In addition to its dimeric state, Hsp90 self-associates upon particular stimuli. The Hsp90 dimer is the building block up to the hexamer that we named “cosy nest”, and the dodecamer results from the association of two hexamers. Oligomers exhibit chaperone activity, but their exact mechanism of action has not yet been determined. One of the best ways to elucidate how oligomers might operate is to study their interactions with co-chaperone proteins known to regulate the Hsp90 chaperone cycle, such as p23 and Aha1. In this review, we summarise recent results and conclude that Hsp90 oligomers are key players in the chaperone cycle. Crucible-shaped quaternary structures likely provide an ideal environment for client protein accommodation and folding, as is the case for other Hsp families. Confirmation of the involvement of Hsp90 oligomers in the chaperone cycle and a better understanding of their functionality will allow us to address some of the more enigmatic aspects of Hsp90 activity. Utilising this knowledge, future work will highlight how Hsp90 oligomers and co-chaperones cooperate to build the structures required to fold or refold numerous different client proteins.

scholarly journals Alterations of the Hsp70/Hsp90 chaperone and the HOP/CHIP co-chaperone system in cancer

2012 ◽  
Vol 17 (3) ◽  
Author(s):  
Eva Ruckova ◽  
Petr Muller ◽  
Rudolf Nenutil ◽  
Borivoj Vojtesek
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cells ◽  
Binding Sites ◽  
Patient Survival ◽  
Proliferating Cells ◽  
Response Elements ◽  
Over Expression ◽  
Hsp90 Activity ◽  
Hsp90 Chaperone ◽  
Client Proteins

AbstractActivation of the Hsp90 chaperone system is a characteristic of cancer cells. The regulation of chaperone activities involves their interaction with cochaperones; therefore we investigated the expression of Hsp70 and Hsp90 and their specific co-chaperones HOP and CHIP in cancer cell lines and primary cancers. Inhibition of Hsp90 by 17AAG increased the levels of Hsp70, Hsp90 and HOP but not CHIP mRNA in cancer cells. These changes are linked to activation of the HSF1 transcription factor and we show that the HOP promoter contains HSF1 binding sites, and that HSF1 binding to the HOP promoter is increased following 17AAG. The lack of alteration in the co-chaperone CHIP is explained by a lack of HSF response elements in the CHIP promoter. Non-proliferating cells expressed higher levels of CHIP and lower HOP, Hsp70 and Hsp90 levels compared to proliferating cells. Decreased expression of CHIP in proliferating cancer cells is in keeping with its proposed tumor suppressor properties, while over-expression of HOP in proliferating cells may contribute to excessive Hsp90 activity and stabilization of client proteins in tumors. In a panel of colorectal cancer samples, increased expression of Hsp70 and an increased ratio of HOP to CHIP were found, and were associated with decreased median survival. These data indicate that multiple changes occur in the chaperone/co-chaperone system in cancer that impact patient survival. It is likely that the ability to identify individual alterations to this system will be beneficial for treatment strategy decisions, particularly those that employ chaperone inhibitors.

scholarly journals Cryo-EM structures reveal a multistep mechanism of Hsp90 activation by co-chaperone Aha1

2020 ◽  
Author(s):  
Yanxin Liu ◽  
Ming Sun ◽  
Alexander G. Myasnikov ◽  
Daniel Elnatan ◽  
Nicolas Delaeter ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Atp Hydrolysis ◽  
Activation Mechanism ◽  
Client Protein ◽  
Protein Maturation ◽  
Structural Framework ◽  
Cryo Electron Microscopy ◽  
Client Proteins ◽  
Rate Limiting

AbstractHsp90 is a ubiquitous molecular chaperone that facilitates the folding and maturation of hundreds of cellular “client” proteins. The ATP-driven client maturation process is regulated by a large number of co-chaperones. Among them, Aha1 is the most potent activator of Hsp90 ATPase activity and thus dramatically affects Hsp90’s client proteins. To understand the Aha1 activation mechanism, we determined full-length Hsp90:Aha1 structures in six different states by cryo-electron microscopy, including nucleotide-free semi-closed, nucleotide-bound pre-hydrolysis, and semi-hydrolyzed states. Our structures demonstrate that the two Aha1 domains can each interact with Hsp90 in two different modes, uncovering a complex multistep activation mechanism. The results show that Aha1 accelerates the chemical step of ATP hydrolysis like a conventional enzyme, but most unusually, catalyzes the rate-limiting large-scale conformational changes of Hsp90 fundamentally required for ATP hydrolysis. Our work provides a structural framework to guide small molecule development targeting this critical modulator of client protein maturation.

scholarly journals Heat Shock Protein 90 Chaperone Regulates the E3 Ubiquitin-Ligase Hakai Protein Stability

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 215 ◽  
Author(s):  
Díaz-Díaz ◽  
Roca-Lema ◽  
Casas-Pais ◽  
Romay ◽  
Colombo ◽  
...  
Keyword(s):  
Heat Shock ◽  
Cancer Therapy ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Heat Shock Protein 90 ◽  
Client Protein ◽  
Hsp90 Chaperone ◽  
Client Proteins ◽  
Chaperone Complex ◽  
Hsp90 Client Protein

The E3 ubiquitin-ligase Hakai binds to several tyrosine-phosphorylated Src substrates, including the hallmark of the epithelial-to-mesenchymal transition E-cadherin, and signals for degradation of its specific targets. Hakai is highly expressed in several human cancers, including colon cancer, and is considered as a drug target for cancer therapy. Here, we report a link between Hakai and the heat shock protein 90 (Hsp90) chaperone complex. Hsp90 participates in the correct folding of its client proteins, allowing them to maintain their stability and activity. Hsp90 inhibitors specifically interfere with the association with its Hsp90 client proteins, and exhibit potent anti-cancer properties. By immunoprecipitation, we present evidence that Hakai interacts with Hsp90 chaperone complex in several epithelial cells and demonstrate that is a novel Hsp90 client protein. Interestingly, by overexpressing and knocking-down experiments with Hakai, we identified Annexin A2 as a Hakai-regulated protein. Pharmacological inhibition of Hsp90 with geldanamycin results in the degradation of Hakai in a lysosome-dependent manner. Interestingly, geldanamycin-induced Hakai degradation is accompanied by an increased expression of E-cadherin and Annexin A2. We also show that geldanamycin suppresses cell motility at least in part through its action on Hakai expression. Taken together, our results identify Hakai as a novel Hsp90 client protein and shed light on the regulation of Hakai stability. Our results open the possibility to the potential use of Hsp90 inhibitors for colorectal cancer therapy through its action on Hakai client protein of Hsp90.

scholarly journals Hsp110 Chaperones Control Client Fate Determination in the Hsp70–Hsp90 Chaperone System

2010 ◽  
Vol 21 (9) ◽  
pp. 1439-1448 ◽  
Author(s):  
Atin K. Mandal ◽  
Patrick A. Gibney ◽  
Nadinath B. Nillegoda ◽  
Maria A. Theodoraki ◽  
Avrom J. Caplan ◽  
...  
Keyword(s):  
Early Stage ◽  
Mechanistic Explanation ◽  
Protein Homeostasis ◽  
Nucleotide Exchange ◽  
Client Protein ◽  
Hsp90 Inhibition ◽  
Nucleotide Exchange Factor ◽  
Model Protein ◽  
Hsp90 Activity ◽  
Hsp90 Chaperone

Heat shock protein 70 (Hsp70) plays a central role in protein homeostasis and quality control in conjunction with other chaperone machines, including Hsp90. The Hsp110 chaperone Sse1 promotes Hsp90 activity in yeast, and functions as a nucleotide exchange factor (NEF) for cytosolic Hsp70, but the precise roles Sse1 plays in client maturation through the Hsp70–Hsp90 chaperone system are not fully understood. We find that upon pharmacological inhibition of Hsp90, a model protein kinase, Ste11ΔN, is rapidly degraded, whereas heterologously expressed glucocorticoid receptor (GR) remains stable. Hsp70 binding and nucleotide exchange by Sse1 was required for GR maturation and signaling through endogenous Ste11, as well as to promote Ste11ΔN degradation. Overexpression of another functional NEF partially compensated for loss of Sse1, whereas the paralog Sse2 fully restored GR maturation and Ste11ΔN degradation. Sse1 was required for ubiquitinylation of Ste11ΔN upon Hsp90 inhibition, providing a mechanistic explanation for its role in substrate degradation. Sse1/2 copurified with Hsp70 and other proteins comprising the “early-stage” Hsp90 complex, and was absent from “late-stage” Hsp90 complexes characterized by the presence of Sba1/p23. These findings support a model in which Hsp110 chaperones contribute significantly to the decision made by Hsp70 to fold or degrade a client protein.

scholarly journals The Hsp90 Chaperone Complex Regulates GDI-dependent Rab Recycling

2006 ◽  
Vol 17 (8) ◽  
pp. 3494-3507 ◽  
Author(s):  
Christine Y. Chen ◽  
William E. Balch
Keyword(s):  
Rab Gtpase ◽  
Rab Gtpases ◽  
Coding System ◽  
Golgi Transport ◽  
Guanine Nucleotide Dissociation Inhibitor ◽  
Hsp90 Activity ◽  
Hsp90 Chaperone ◽  
Chaperone Complex ◽  
Hsp 90 ◽  
Synaptic Vesicle Fusion

Rab GTPase regulated hubs provide a framework for an integrated coding system, the membrome network, that controls the dynamics of the specialized exocytic and endocytic membrane architectures found in eukaryotic cells. Herein, we report that Rab recycling in the early exocytic pathways involves the heat-shock protein (Hsp)90 chaperone system. We find that Hsp90 forms a complex with guanine nucleotide dissociation inhibitor (GDI) to direct recycling of the client substrate Rab1 required for endoplasmic reticulum (ER)-to-Golgi transport. ER-to-Golgi traffic is inhibited by the Hsp90-specific inhibitors geldanamycin (GA), 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG), and radicicol. Hsp90 activity is required to form a functional GDI complex to retrieve Rab1 from the membrane. Moreover, we find that Hsp90 is essential for Rab1-dependent Golgi assembly. The observation that the highly divergent Rab GTPases Rab1 involved in ER-to-Golgi transport and Rab3A involved in synaptic vesicle fusion require Hsp90 for retrieval from membranes lead us to now propose that the Hsp90 chaperone system may function as a general regulator for Rab GTPase recycling in exocytic and endocytic trafficking pathways involved in cell signaling and proliferation.

scholarly journals Conformational variability in proteins bound to single-stranded DNA: a new benchmark for new docking perspectives

2021 ◽  
Author(s):  
Dominique MIAS-LUCQUIN ◽  
Isaure Chauvot de Beauchêne
Keyword(s):  
Protein Data Bank ◽  
Conformational Changes ◽  
Molecular Interactions ◽  
Protein Structures ◽  
Data Bank ◽  
Computational Docking ◽  
Ssdna Binding ◽  
Conformational Variability ◽  
High Flexibility ◽  
Docking Benchmark

We explored the Protein Data-Bank (PDB) to collect protein-ssDNA structures and create a multi-conformational docking benchmark including both bound and unbound protein structures. Due to ssDNA high flexibility when not bound, no ssDNA unbound structure is included. For the 143 groups identified as bound-unbound structures of the same protein , we studied the conformational changes in the protein induced by the ssDNA binding. Moreover, based on several bound or unbound protein structures in some groups, we also assessed the intrinsic conformational variability in either bound or unbound conditions, and compared it to the supposedly binding-induced modifications. This benchmark is, to our knowledge, the first attempt made to peruse available structures of protein – ssDNA interactions to such an extent, aiming to improve computational docking tools dedicated to this kind of molecular interactions.

Myopathy mutations in DNAJB6 slow conformer specific substrate processing that is rescued by NEF modulation

2021 ◽  
Author(s):  
Ankan K. Bhadra ◽  
Michael J. Rau ◽  
Jil A. Daw ◽  
James A.J. Fitzpatrick ◽  
Conrad C. Weihl ◽  
...  
Keyword(s):  
Chaperone Activity ◽  
Specific Substrate ◽  
Yeast Prion ◽  
Protein Aggregate ◽  
Client Proteins ◽  
Chaperone Interactions ◽  
Chaperone Network ◽  
Shock Proteins ◽  
Substrate Processing

Molecular chaperones, or heat shock proteins (HSPs), protect against the toxic misfolding and aggregation of proteins. As such, mutations or deficiencies within the chaperone network can lead to disease. In fact, dominant mutations in DNAJB6 (Hsp40/Sis1), an Hsp70 co-chaperone, leads to a protein aggregate myopathy termed Limb-Girdle Muscular Dystrophy Type D1 (LGMDD1). DNAJB6 client proteins and co-chaperone interactions in skeletal muscle are not known. Here, we used the yeast prion model client in conjunction with in vitro chaperone activity assays to gain mechanistic insights, and found that LGMDD1 mutants affect Hsp40 functions. Strikingly, the mutants changed the structure of client protein aggregates, as determined by altered distribution of prion strains. They also impair the Hsp70 ATPase cycle, dimerization, and substrate processing and consequently poison the function of wild-type protein. These results define the mechanisms by which LGMDD1 mutations alter chaperone activity and provide avenues for therapeutic intervention.

Closing remarks

1975 ◽  
Vol 272 (915) ◽  
pp. 195-198
Keyword(s):  
Metal Ions ◽  
Conformational Changes ◽  
Mechanical Strain ◽  
Complexing Agent ◽  
Electric Polarizability ◽  
Individual Structure ◽  
Biological Recognition ◽  
The Stability ◽  
High Flexibility ◽  
General Assent

Only a bold man would dare attempt a synthesis of the wide-ranging discussions of the last two days, let alone distil from them any general principles of biological recognition. The only sentiment which could command general assent is one of gratitude to the Society, the organizers and the contributors for putting before us such a fascinating collection of papers and letting us sharpen our wits on so much new knowledge. The following remarks will therefore be nothing more than personal footnotes; if they omit reference to much of the work which has been presented, and only mention a few of the issues that have been raised, that is a matter of sheer necessity, not of personal prejudice. In our first session we began by reviewing the physical chemistry of molecular interactions in terms of quantum mechanics and statistical mechanics. Professor Buckingham warned us against the temptation of regarding molecular association energies as made up of additive contributions from pairs of atoms or ions, and Professor Symons stressed the highly individual structure-forming habits of water, which make it so difficult to interpret its solvation properties in terms of simplified models which treat water as a uniform dielectric, or as a mixture of monomers and high polymers. Professor Truter then introduced us to the structures of the complexes formed by ferrichrome A, nonactin and other biological agents with metal ions of various kinds. She drew attention to the large conformational changes which often accompany complex formation, and suggested that some at least of these agents owe their specificity to their high flexibility. Presumably one should interpret this generalization in terms of an ability of the complexing agent to meet very precisely the stereochemical needs of one particular ion, coupled with an inability to meet the precise needs of other ions without a certain amount of mechanical strain. To take a single example, it is not immediately obvious how the needs of T1+ differ from those of the alkali metal ions; but that is because we tend to overlook the effect of ionic polarization on the stability of the solvated ion. The T1 + ion, because of its outer electron pair, has a low-lying dipole transition (6s -> 6p) which confers on it a high electric polarizability. As a result, a set of negative ligands on one side induce a negative charge on the other side, and this will hinder the approach of further ligands on that side - as suggested by the curious stereochemistry of some of Professor Truter’s T1 + complexes.

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