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Journal of Molecular Biology Jul 2022Hsp70 chaperones bind short monomeric peptides with a weak characteristic affinity in the low micromolar range, but can also bind some aggregates, fibrils, and amyloids,...
Hsp70 chaperones bind short monomeric peptides with a weak characteristic affinity in the low micromolar range, but can also bind some aggregates, fibrils, and amyloids, with low nanomolar affinity. While this differential affinity enables Hsp70 to preferentially target potentially toxic aggregates, it is unknown how a chaperone can differentiate between monomeric and aggregated states of a client protein and why preferential binding is only observed for some aggregated clients but not others. Here we examine the interaction of BiP (the Hsp70 paralog in the endoplasmic reticulum) with the client proIGF2, the pro-protein form of IGF2 that includes a long and mostly disordered E-peptide region that promotes proIGF2 oligomerization. By dissecting the mechanism by which BiP targets proIGF2 and E-peptide oligomers we discover that electrostatic attraction is a powerful driving force for oligomer recognition. We identify the specific BiP binding sites on proIGF2 and as monomers they bind BiP with characteristically weak affinity in the low micromolar range, but electrostatic attraction to E-peptide oligomers boosts the affinity to the low nanomolar level. The dominant role of electrostatics is manifested kinetically as a steering force that accelerates the binding of BiP to E-peptide oligomers by approximately two orders of magnitude as compared against monomeric peptides. Electrostatic targeting of Hsp70 provides an explanation for why preferential binding has been observed for some aggregated clients but not others, as all the currently-documented cases in which Hsp70 binds aggregates with high-affinity involve clients that have an opposite charge to Hsp70.
Topics: Endoplasmic Reticulum Chaperone BiP; Escherichia coli; HSP70 Heat-Shock Proteins; Heat-Shock Proteins; Humans; Molecular Chaperones; Peptides; Protein Binding; Static Electricity
PubMed: 35597552
DOI: 10.1016/j.jmb.2022.167638 -
ELife May 2018Molecular chaperones alter the folding properties of cellular proteins via mechanisms that are not well understood. Here, we show that Trigger Factor (TF), an...
Molecular chaperones alter the folding properties of cellular proteins via mechanisms that are not well understood. Here, we show that Trigger Factor (TF), an ATP-independent chaperone, exerts strikingly contrasting effects on the folding of non-native proteins as it transitions between a monomeric and a dimeric state. We used NMR spectroscopy to determine the atomic resolution structure of the 100 kDa dimeric TF. The structural data show that some of the substrate-binding sites are buried in the dimeric interface, explaining the lower affinity for protein substrates of the dimeric compared to the monomeric TF. Surprisingly, the dimeric TF associates faster with proteins and it exhibits stronger anti-aggregation and holdase activity than the monomeric TF. The structural data show that the dimer assembles in a way that substrate-binding sites in the two subunits form a large contiguous surface inside a cavity, thus accounting for the observed accelerated association with unfolded proteins. Our results demonstrate how the activity of a chaperone can be modulated to provide distinct functional outcomes in the cell.
Topics: Binding Sites; Escherichia coli; Escherichia coli Proteins; Molecular Chaperones; Peptidylprolyl Isomerase; Protein Binding; Protein Conformation; Protein Folding; Protein Multimerization
PubMed: 29714686
DOI: 10.7554/eLife.35731 -
The International Journal of... Dec 2004Chaperone-mediated autophagy is one of several lysosomal pathways of proteolysis. This pathway is activated by physiological stresses such as prolonged starvation.... (Review)
Review
Chaperone-mediated autophagy is one of several lysosomal pathways of proteolysis. This pathway is activated by physiological stresses such as prolonged starvation. Cytosolic proteins with particular peptide sequence motifs are recognized by a complex of molecular chaperones and delivered to lysosomes. No vesicular traffic is required for this protein degradation pathway, so it differs from microautophagy and macroautophagy. Protein substrates bind to a receptor in the lysosomal membrane, the lysosome-associated membrane protein (lamp) type 2a. Levels of lamp2a in the lysosomal membrane are controlled by alterations in the lamp2a half-life as well as by the dynamic distribution of the protein between the lysosomal membrane and the lumen. Substrate proteins are unfolded before transport into the lysosome lumen, and the transport of substrate proteins requires a molecular chaperone within the lysosomal lumen. The exact roles of this lysosomal chaperone remain to be defined. The mechanisms of chaperone-mediated autophagy are similar to mechanisms of protein import into mitochondria, chloroplasts, and the endoplasmic reticulum.
Topics: Amino Acid Motifs; Amino Acid Sequence; Animals; Antigens, CD; Autophagy; Cytosol; HSC70 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Humans; Lysosomal Membrane Proteins; Lysosomes; Molecular Chaperones; Proteins
PubMed: 15325583
DOI: 10.1016/j.biocel.2004.02.013 -
Molecular basis for different substrate-binding sites and chaperone functions of the BRICHOS domain.Protein Science : a Publication of the... Jul 2024Proteins can misfold into fibrillar or amorphous aggregates and molecular chaperones act as crucial guardians against these undesirable processes. The BRICHOS chaperone...
Proteins can misfold into fibrillar or amorphous aggregates and molecular chaperones act as crucial guardians against these undesirable processes. The BRICHOS chaperone domain, found in several otherwise unrelated proproteins that contain amyloidogenic regions, effectively inhibits amyloid formation and toxicity but can in some cases also prevent non-fibrillar, amorphous protein aggregation. Here, we elucidate the molecular basis behind the multifaceted chaperone activities of the BRICHOS domain from the Bri2 proprotein. High-confidence AlphaFold2 and RoseTTAFold predictions suggest that the intramolecular amyloidogenic region (Bri23) is part of the hydrophobic core of the proprotein, where it occupies the proposed amyloid binding site, explaining the markedly reduced ability of the proprotein to prevent an exogenous amyloidogenic peptide from aggregating. However, the BRICHOS-Bri23 complex maintains its ability to form large polydisperse oligomers that prevent amorphous protein aggregation. A cryo-EM-derived model of the Bri2 BRICHOS oligomer is compatible with surface-exposed hydrophobic motifs that get exposed and come together during oligomerization, explaining its effects against amorphous aggregation. These findings provide a molecular basis for the BRICHOS chaperone domain function, where distinct surfaces are employed against different forms of protein aggregation.
Topics: Molecular Chaperones; Binding Sites; Humans; Protein Domains; Adaptor Proteins, Signal Transducing; Models, Molecular; Hydrophobic and Hydrophilic Interactions
PubMed: 38864729
DOI: 10.1002/pro.5063 -
The Journal of General and Applied... Jun 2023Protein synthesis in Corynebacterium glutamicum is critical for applications in biotechnology and medicine. However, the use of C. glutamicum for protein production is...
Protein synthesis in Corynebacterium glutamicum is critical for applications in biotechnology and medicine. However, the use of C. glutamicum for protein production is limited by its low expression and aggregation. To overcome these limitations, a molecular chaperone plasmid system was developed in this study to improve the efficiency of recombinant protein synthesis in C. glutamicum. The effect of molecular chaperones on target protein synthesis (Single-chain variable fragment, Scfv) under three different promoter strengths was tested. In addition, the plasmid containing the molecular chaperone and target protein was verified for growth stability and plasmid stability. This expression model was further validated using two recombinant proteins, human interferon-beta (Hifn) and hirudin variant III (Rhv3). Finally, the Rhv3 protein was purified, and analysis of Rhv3 activity confirmed that the use of a molecular chaperone led to an improvement in test protein synthesis. Thus, the use of molecular chaperones is believed to will improve recombinant proteins synthesis in C. glutamicum.
Topics: Humans; Corynebacterium glutamicum; Recombinant Proteins; Plasmids; Promoter Regions, Genetic; Molecular Chaperones
PubMed: 36878578
DOI: 10.2323/jgam.2022.10.002 -
Biomolecules Jan 2023Heat shock protein 90 (Hsp90) is a highly conserved molecular chaperone that assists in the maturation of many client proteins involved in cellular signal transduction.... (Review)
Review
Heat shock protein 90 (Hsp90) is a highly conserved molecular chaperone that assists in the maturation of many client proteins involved in cellular signal transduction. As a regulator of cellular signaling processes, it is vital for the maintenance of cellular proteostasis and adaptation to environmental stresses. Emerging research shows that Hsp90 function in an organism goes well beyond intracellular proteostasis. In metazoans, Hsp90, as an environmentally responsive chaperone, is involved in inter-tissue stress signaling responses that coordinate and safeguard cell nonautonomous proteostasis and organismal health. In this way, Hsp90 has the capacity to influence evolution and aging, and effect behavioral responses to facilitate tissue-defense systems that ensure organismal survival. In this review, I summarize the literature on the organismal roles of Hsp90 uncovered in multicellular organisms, from plants to invertebrates and mammals.
Topics: Humans; Animals; HSP90 Heat-Shock Proteins; Molecular Chaperones; Signal Transduction; Proteostasis; Stress, Physiological; Mammals
PubMed: 36830620
DOI: 10.3390/biom13020251 -
Communications Biology Jan 2020Molecular chaperones play important roles in preventing protein misfolding and its potentially harmful consequences. Deterioration of molecular chaperone systems upon...
Molecular chaperones play important roles in preventing protein misfolding and its potentially harmful consequences. Deterioration of molecular chaperone systems upon ageing are thought to underlie age-related neurodegenerative diseases, and augmenting their activities could have therapeutic potential. The dementia relevant domain BRICHOS from the Bri2 protein shows qualitatively different chaperone activities depending on quaternary structure, and assembly of monomers into high-molecular weight oligomers reduces the ability to prevent neurotoxicity induced by the Alzheimer-associated amyloid-β peptide 1-42 (Aβ42). Here we design a Bri2 BRICHOS mutant (R221E) that forms stable monomers and selectively blocks a main source of toxic species during Aβ42 aggregation. Wild type Bri2 BRICHOS oligomers are partly disassembled into monomers in the presence of the R221E mutant, which leads to potentiated ability to prevent Aβ42 toxicity to neuronal network activity. These results suggest that the activity of endogenous molecular chaperones may be modulated to enhance anti-Aβ42 neurotoxic effects.
Topics: Amyloid; Amyloid beta-Peptides; Hippocampus; Kinesis; Models, Molecular; Molecular Chaperones; Protein Aggregates; Protein Binding; Protein Conformation; Protein Multimerization; Structure-Activity Relationship
PubMed: 31959875
DOI: 10.1038/s42003-020-0757-z -
Free Radical Biology & Medicine Aug 2020Large-size subunit catalases (LSCs) have a C-terminal domain that is structurally similar to DJ-1 and Hsp31 proteins, which have well documented molecular chaperone...
Large-size subunit catalases (LSCs) have a C-terminal domain that is structurally similar to DJ-1 and Hsp31 proteins, which have well documented molecular chaperone activity. Like chaperones, LSCs are abundant proteins that are induced under stress conditions and during cell differentiation in different microorganisms. Here we document that the C-terminal domain of LSCs assist other proteins to preserve their active conformation. Heat, urea, or HO denaturation of alcohol dehydrogenase was prevented by LSCs or the C-terminal domain of Catalase-3 (TDC3); in contrast, small-size subunit catalases (SSCs) or LSCs without the C-terminal domain (C3 or C63) did not have this effect. Similar results were obtained if the alcohol dehydrogenase was previously denatured by heat and then the different catalases or truncated enzymes were added. The TDC3 also protected both the C3 and the bovine liver catalase from heat denaturation. The chaperone activity of CAT-3 or the TDC3 increased survival of E. coli under different stress conditions whereas the C3 did not. It is concluded that the C-terminal domain of LSCs has a chaperone activity that is instrumental for cellular resistance to stress conditions, such as oxidative stress that leads to cell differentiation in filamentous fungi.
Topics: Animals; Catalase; Cattle; Escherichia coli; Hydrogen Peroxide; Molecular Chaperones; Protein Folding
PubMed: 32502516
DOI: 10.1016/j.freeradbiomed.2020.05.020 -
Biochimica Et Biophysica Acta Aug 2014Nascent polypeptides emerging from the ribosome are assisted by a pool of molecular chaperones and targeting factors, which enable them to efficiently partition as... (Review)
Review
Nascent polypeptides emerging from the ribosome are assisted by a pool of molecular chaperones and targeting factors, which enable them to efficiently partition as cytosolic, integral membrane or exported proteins. Extensive genetic and biochemical analyses have significantly expanded our knowledge of chaperone tasking throughout this process. In bacteria, it is known that the folding of newly-synthesized cytosolic proteins is mainly orchestrated by three highly conserved molecular chaperones, namely Trigger Factor (TF), DnaK (HSP70) and GroEL (HSP60). Yet, it has been reported that these major chaperones are strongly involved in protein translocation pathways as well. This review describes such essential molecular chaperone functions, with emphasis on both the biogenesis of inner membrane proteins and the post-translational targeting of presecretory proteins to the Sec and the twin-arginine translocation (Tat) pathways. Critical interplay between TF, DnaK, GroEL and other molecular chaperones and targeting factors, including SecB, SecA, the signal recognition particle (SRP) and the redox enzyme maturation proteins (REMPs) is also discussed. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
Topics: Bacteria; Cell Membrane; Chaperonin 60; HSP70 Heat-Shock Proteins; Molecular Chaperones; Oxidation-Reduction; Protein Transport; Signal Recognition Particle
PubMed: 24269840
DOI: 10.1016/j.bbamcr.2013.11.007 -
Acta Biochimica Et Biophysica Sinica May 2014Small heat-shock proteins (sHSPs) are ubiquitous ATP-independent molecular chaperones that play crucial roles in protein quality control in cells. They are able to... (Review)
Review
Small heat-shock proteins (sHSPs) are ubiquitous ATP-independent molecular chaperones that play crucial roles in protein quality control in cells. They are able to prevent the aggregation and/or inactivation of various non-native substrate proteins and assist the refolding of these substrates independently or under the help of other ATP-dependent chaperones. Substrate recognition and binding by sHSPs are essential for their chaperone functions. This review focuses on what natural substrate proteins an sHSP protects and how it binds the substrates in cells under fluctuating conditions. It appears that sHSPs of prokaryotes, although being able to bind a wide range of cellular proteins, preferentially protect certain classes of functional proteins, such as translation-related proteins and metabolic enzymes, which may well explain why they could increase the resistance of host cells against various stresses. Mechanistically, the sHSPs of prokaryotes appear to possess numerous multi-type substrate-binding residues and are able to hierarchically activate these residues in a temperature-dependent manner, and thus act as temperature-regulated chaperones. The mechanism of hierarchical activation of substrate-binding residues is also discussed regarding its implication for eukaryotic sHSPs.
Topics: Heat-Shock Proteins; Molecular Chaperones; Protein Binding
PubMed: 24449783
DOI: 10.1093/abbs/gmt152