Evidence for Hsp90 Co-chaperones in Regulating Hsp90 Function and Promoting Client Protein Folding

Protein folding while chaperone bound is dependent on weak interactions

Nature Communications ◽

10.1038/s41467-019-12774-6 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Kevin Wu ◽

Frederick Stull ◽

Changhan Lee ◽

James C. A. Bardwell

Keyword(s):

Protein Folding ◽

Weak Interactions ◽

Client Protein ◽

Native State ◽

Folding Rate ◽

Sufficient Strength ◽

Surprising Observation

Abstract It is generally assumed that protein clients fold following their release from chaperones instead of folding while remaining chaperone-bound, in part because binding is assumed to constrain the mobility of bound clients. Previously, we made the surprising observation that the ATP-independent chaperone Spy allows its client protein Im7 to fold into the native state while continuously bound to the chaperone. Spy apparently permits sufficient client mobility to allow folding to occur while chaperone bound. Here, we show that strengthening the interaction between Spy and a recently discovered client SH3 strongly inhibits the ability of the client to fold while chaperone bound. The more tightly Spy binds to its client, the more it slows the folding rate of the bound client. Efficient chaperone-mediated folding while bound appears to represent an evolutionary balance between interactions of sufficient strength to mediate folding and interactions that are too tight, which tend to inhibit folding.

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Synthesis and Biological Activity of 3-(Heteroaryl)quinolin-2(1H)-ones Bis-Heterocycles as Potential Inhibitors of the Protein Folding Machinery Hsp90

Molecules ◽

10.3390/molecules27020412 ◽

2022 ◽

Vol 27 (2) ◽

pp. 412

Author(s):

Enrique L. Larghi ◽

Alexandre Bruneau ◽

Félix Sauvage ◽

Mouad Alami ◽

Juliette Vergnaud-Gauduchon ◽

...

Keyword(s):

Protein Folding ◽

Biological Activity ◽

Cell Lines ◽

Biological Effect ◽

Cross Coupling ◽

Easy Access ◽

Client Protein ◽

Convenient Approach ◽

Potential Inhibitors ◽

Sar Study

In the context of our SAR study concerning 6BrCaQ analogues as C-terminal Hsp90 inhibitors, we designed and synthesized a novel series of 3-(heteroaryl)quinolin-2(1H), of types 3, 4, and 5, as a novel class of analogues. A Pd-catalyzed Liebeskind–Srogl cross-coupling was developed as a convenient approach for easy access to complex purine architectures. This series of analogues showed a promising biological effect against MDA-MB231 and PC-3 cancer cell lines. This study led to the identification of the best compounds, 3b (IC50 = 28 µM) and 4e, which induce a significant decrease of CDK-1 client protein and stabilize the levels of Hsp90 and Hsp70 without triggering the HSR response.

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Snapshots of actin and tubulin folding inside the TRiC chaperonin

10.1101/2021.03.26.436673 ◽

2021 ◽

Author(s):

John J. Kelly ◽

Dale Tranter ◽

Els Pardon ◽

Gamma Chi ◽

Holger Kramer ◽

...

Keyword(s):

Electron Microscopy ◽

Protein Folding ◽

Structure Determination ◽

Cytoskeletal Proteins ◽

Chamber Wall ◽

Atomistic Model ◽

Structural Studies ◽

Client Protein ◽

Client Proteins ◽

Unstructured Regions

AbstractThe integrity of a cell’s proteome depends on correct folding of polypeptides by chaperonins. The TCP-1 ring chaperonin (TRiC) acts as obligate folder for >10% of cytosolic proteins, including cytoskeletal proteins actin and tubulin. While its architecture and how it recognises folding substrates is emerging from structural studies, the subsequent fate of substrates inside the TRiC chamber is not defined. We trapped endogenous human TRiC with substrates (actin, tubulin) and co-chaperone (PhLP2A) at different folding stages, for structure determination by cryogenic electron microscopy. The already-folded regions of client proteins are anchored at the chamber wall, positioning unstructured regions towards the central space to achieve their folding. Substrates engage with different sections of the chamber during the folding cycle, coupled to TRiC open-and-close transitions. Furthermore, the cochaperone PhLP2A modulates folding, acting as a molecular strut between substrate and TRiC chamber. Our structural snapshots piece together an emerging atomistic model of client protein folding through TRiC.

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Heterogeneous binding of the SH3 client protein to the DnaK molecular chaperone

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1505173112 ◽

2015 ◽

Vol 112 (31) ◽

pp. E4206-E4215 ◽

Cited By ~ 28

Author(s):

Jung Ho Lee ◽

Dongyu Zhang ◽

Christopher Hughes ◽

Yusuke Okuno ◽

Ashok Sekhar ◽

...

Keyword(s):

Protein Folding ◽

Molecular Chaperone ◽

Structural Changes ◽

Vital Role ◽

Conformational Sampling ◽

Client Protein ◽

Dynamical Heterogeneity ◽

Src Homology ◽

Multiple Conformations ◽

Free Environment

The molecular chaperone heat shock protein 70 (Hsp70) plays a vital role in cellular processes, including protein folding and assembly, and helps prevent aggregation under physiological and stress-related conditions. Although the structural changes undergone by full-length client proteins upon interaction with DnaK (i.e., Escherichia coli Hsp70) are fundamental to understand chaperone-mediated protein folding, these changes are still largely unexplored. Here, we show that multiple conformations of the SRC homology 3 domain (SH3) client protein interact with the ADP-bound form of the DnaK chaperone. Chaperone-bound SH3 is largely unstructured yet distinct from the unfolded state in the absence of DnaK. The bound client protein shares a highly flexible N terminus and multiple slowly interconverting conformations in different parts of the sequence. In all, there is significant structural and dynamical heterogeneity in the DnaK-bound client protein, revealing that proteins may undergo some conformational sampling while chaperone-bound. This result is important because it shows that the surface of the Hsp70 chaperone provides an aggregation-free environment able to support part of the search for the native state.

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