Extensive Sampling of the Cavity of the GroEL Nanomachine by Protein Substrates Probed by Paramagnetic Relaxation Enhancement

Wälti, Marielle A.; Libich, David S.; Clore, G. Marius

doi:10.1021/acs.jpclett.8b01586

Cited by 11 publications

(10 citation statements)

References 22 publications

(62 reference statements)

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“…The separation between region 1 and the other two regions is sufficient to permit Aβ42 to contact two adjacent subunits of GroEL simultaneously. In addition, the methionine/glycine-rich C-terminal disordered tail of GroEL may also transiently contact bound Aβ42, as has been demonstrated using paramagnetic relaxation enhancement measurements for the interaction of a small folded SH3 domain with GroEL (31).…”

Section: Resultsmentioning

confidence: 87%

Probing the mechanism of inhibition of amyloid-β(1–42)–induced neurotoxicity by the chaperonin GroEL

Wälti

Steiner

Meng

et al. 2018

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

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The human chaperonin Hsp60 is thought to play a role in the progression of Alzheimer’s disease by mitigating against intracellular β-amyloid stress. Here, we show that the bacterial homolog GroEL (51% sequence identity) reduces the neurotoxic effects of amyloid-β(1–42) (Aβ42) on human neural stem cell-derived neuronal cultures. To understand the mechanism of GroEL-mediated abrogation of neurotoxicity, we studied the interaction of Aβ42 with GroEL using a variety of biophysical techniques. Aβ42 binds to GroEL as a monomer with a lifetime of ∼1 ms, as determined from global analysis of multiple relaxation-based NMR experiments. Dynamic light scattering demonstrates that GroEL dissolves small amounts of high–molecular-weight polydisperse aggregates present in fresh soluble Aβ42 preparations. The residue-specific transverse relaxation rate profile for GroEL-bound Aβ42 reveals the presence of three anchor-binding regions (residues 16–21, 31–34, and 40–41) located within the hydrophobic GroEL-consensus binding sequences. Single-molecule FRET analysis of Aβ42 binding to GroEL results in no significant change in the FRET efficiency of a doubly labeled Aβ42 construct, indicating that Aβ42 samples a random coil ensemble when bound to GroEL. Finally, GroEL substantially slows down the disappearance of NMR visible Aβ42 species and the appearance of Aβ42 protofibrils and fibrils as monitored by electron and atomic force microscopies. The latter observations correlate with the effect of GroEL on the time course of Aβ42-induced neurotoxicity. These data provide a physical basis for understanding how Hsp60 may serve to slow down the progression of Alzheimer’s disease.

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Section: Resultsmentioning

confidence: 87%

Probing the mechanism of inhibition of amyloid-β(1–42)–induced neurotoxicity by the chaperonin GroEL

Wälti

Steiner

Meng

et al. 2018

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

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“…The data show at atomic resolution that the chaperones interact with the model clients Im7 and SH3 through their locally frustrated regions, regardless of the local structure or a specific sequence motif (Figure ). Intriguingly, the same recognition site on SH3 was also shown to be the binding site of the ATP‐dependent chaperone GroEL, and the same principle of recognizing frustration was also found to underlie dimer formation of the chaperone TF . Overall, these data indicate that the principle of recognizing frustrated segments in native clients might be a general functional feature of molecular chaperones.…”

Section: Chaperones Recognize Frustrated Surfaces Of Client Proteinsmentioning

confidence: 99%

Frustrated Interfaces Facilitate Dynamic Interactions between Native Client Proteins and Holdase Chaperones

Hiller

2019

ChemBioChem

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The successful execution of cellular processes depends on well-folded proteins in all cellular compartments. Although some nascent proteins are able to fold spontaneously,alarge number of proteins are less stable and vulnerable to misfolding and aggregation in the highlyc rowded cellular environment. Many proteins are just marginally stable in their physiological environment and susceptible to misfolding and aggregation,e specially under cellular stress conditions. Therefore, cells have evolved multiple different molecular chaperones to bind cellular proteins,b oth in unfolded and folded forms. Consequently,m olecular chaperones are implicated in aw ide variety of cellular processes, including protein biogenesis, protection of the proteome from stress;r ecovery of individual proteins from aggregates;p rotein folding;f acilitation of protein translocation across membranes;a nd more specialized roles, such as disassembly of particularprotein complexes. [1][2][3] In the case of cellular stress conditions, such as upon heat shock, in cancer cells, or infected cells, the expression levels of molecular chaperones is highly upregulated. [4,5] Unlike classical specific interactors, such as antibody-antigen pairs, chaperones are heavy-dutym olecular machines that operate on a wide clientome, that is, ar ange of many different clients, including nascenta nd native proteins. [6,7] For instance, in prokaryotic cells, the chaperone trigger factor (TF) binds at least 68 different full-length proteins from Escherichia coli lysates, [8] or in eukaryotic cells, the chaperone machinery Hsp70/Hsp90 binds 60 %o fk inases, 30 %o fu biquitin ligases, and 7% of transcription factor. [9][10][11] This interaction betweenc haperones and native client proteinsc an occur in an ATP-dependent or -independent manner and can serve the purpose of preventing aggregation and to assemble clients into quaternary structures and complexes. [11,12] In eukaryotes, chaperones binding folded clientsa re also involved in recruiting proteins to thep roteasome for turnover,b ringing proteins to the endosome or lysosome for autophagy, [13] and promoting client protein binding with ligands. [14] Descriptionso fc haperone-clienti nteractions at the atomic level are necessary to fully understand chaperone function. Considerable knowledge has been accumulated over the past decadeo nt he molecular mechanisms of chaperones aiding nascent protein folding, preventing protein aggregation, [15][16][17] yet many fundamental questions remain unanswered.S pecifically,u ntil recently,w eknew little about how chaperones recognizen ative client proteins, [18][19][20][21] and how these chaperones can act in ag eneric manner on many different proteins.T hese questionsa re difficultt oa ddress because the underlying molecular mechanisms involvei nteractions that are transient and dynamic. For studies of protein-protein interactions, am ultitude of experimental methods exist, including X-ray crystallography;c ryo-electronm icroscopy;a nd biophysical methods, such as small-angle ...

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“…Recent studies on the interactions between chaperones Spy, Skp and SurA and model clients Im7 and SH3 suggested a mode of interaction, in which chaperones recognize and bind locally frustrated surfaces of client proteins in a dynamic way . The same binding site on SH3 was also found to be engaged in interaction with the chaperonin GroEL, further supporting the notion that recognizing locally frustrated regions could be a common principle for chaperone‐client interactions where the client is a natively well‐folded protein . Moreover, a random mutagenesis study of GroEL‐client interaction using green fluorescent protein (GFP) as a model substrate demonstrated that mutations at highly frustrated positions correlate with decreased GroEL dependence during folding, whereas mutations at low frustration positions correlate with increased GroEL dependence .…”

Section: Chaperone‐client Interactionsmentioning

confidence: 70%

Mechanisms of Chaperones as Active Assistant/Protector for Proteins: Insights from NMR Studies

et al. 2020

Chin. J. Chem.

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Molecular chaperones are diverse families of proteins that play key roles in protein homeostasis. They assist the folding of client proteins or prevent them from irreversible aggregation under stress conditions. Diverse chaperone families contribute to different aspects of protein homeostasis by interacting with a wide range of client proteins. Despite the vital roles of chaperones in cell survival, the molecular mechanisms underlying chaperone functions remain elusive, due to the non‐specificity of chaperone‐client interactions and the intrinsic flexibility of the clients. Our understanding of the chaperone functional mechanisms, especially regarding chaperone‐client interactions, has greatly expanded in recent years, thanks to the significant contribution from various NMR studies. Solution NMR methods have unique advantages in characterizing disordered protein structures, detecting weak and non‐specific interactions, and probing conformational dynamics of proteins and protein complexes, etc., and therefore are especially powerful in the studies of chaperone structure‐function relationships. In this review, we summarize some of the current knowledge of molecular chaperones, with emphasis on common features of chaperone‐client interactions and examples on a number of specific systems in which solution NMR methods were used to provide essential insights into their functional mechanisms.

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Extensive Sampling of the Cavity of the GroEL Nanomachine by Protein Substrates Probed by Paramagnetic Relaxation Enhancement

Cited by 11 publications

References 22 publications

Probing the mechanism of inhibition of amyloid-β(1–42)–induced neurotoxicity by the chaperonin GroEL

Probing the mechanism of inhibition of amyloid-β(1–42)–induced neurotoxicity by the chaperonin GroEL

Frustrated Interfaces Facilitate Dynamic Interactions between Native Client Proteins and Holdase Chaperones

Mechanisms of Chaperones as Active Assistant/Protector for Proteins: Insights from NMR Studies

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