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The Journal of Biological Chemistry Feb 2004Although calmodulin is known to be a component of the Hsp70/Hsp90 multichaperone complex, the functional role of the protein remains uncertain. In this study, we have...
Although calmodulin is known to be a component of the Hsp70/Hsp90 multichaperone complex, the functional role of the protein remains uncertain. In this study, we have identified S100A1, but not calmodulin or other S100 proteins, as a potent molecular chaperone and a new member of the multichaperone complex. Glutathione S-transferase pull-down assays and co-immunoprecipitation experiments indicated the formation of stable complexes between S100A1 and Hsp90, Hsp70, FKBP52, and CyP40 both in vitro and in mammalian cells. S100A1 potently protected citrate synthase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, and rhodanese from heat-induced aggregation and suppressed the aggregation of chemically denatured rhodanese and citrate synthase during the refolding pathway. In addition, S100A1 suppressed the heat-induced inactivation of citrate synthase activity, similar to that for Hsp90 and p23. The chaperone activity of S100A1 was antagonized by calmodulin antagonists, such as fluphenazine and prenylamine, that is, indeed an intrinsic function of the protein. The overexpression of S100A1 in COS-7 cells protected transiently expressed firefly luciferase and Escherichia coli beta-galactosidase from inactivation during heat shock. The results demonstrate a novel physiological function for S100A1 and bring us closer to a comprehensive understanding of the molecular mechanisms of the Hsp70/Hsp90 multichaperone complex.
Topics: Amino Acid Sequence; Animals; Brain; Calcium; Calcium-Binding Proteins; Calmodulin; Carrier Proteins; Cattle; Cyclophilins; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Humans; In Vitro Techniques; Kinetics; Macromolecular Substances; Molecular Chaperones; Molecular Sequence Data; Peptidylprolyl Isomerase; Recombinant Fusion Proteins; S100 Proteins; Surface Plasmon Resonance; Tacrolimus Binding Proteins
PubMed: 14638689
DOI: 10.1074/jbc.M309014200 -
Biochimica Et Biophysica Acta Mar 2012Cellular environments are highly complex and contain a copious variety of proteins that must operate in unison to achieve homeostasis. To guide and preserve order,... (Review)
Review
Cellular environments are highly complex and contain a copious variety of proteins that must operate in unison to achieve homeostasis. To guide and preserve order, multifaceted molecular chaperone networks are present within each cell type. To handle the vast client diversity and regulatory demands, a wide assortment of chaperones are needed. In addition to the classic heat shock proteins, cochaperones with inherent chaperoning abilities (e.g., p23, Hsp40, Cdc37, etc.) are likely used to complete a system. In this review, we focus on the HSP90-associated cochaperones and provide evidence supporting a model in which select cochaperones are used to differentially modulate target proteins, contribute to combinatorial client regulation, and increase the overall reach of a cellular molecular chaperone network. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
Topics: HSP90 Heat-Shock Proteins; Humans; Molecular Chaperones; Protein Binding; Signal Transduction
PubMed: 21889547
DOI: 10.1016/j.bbamcr.2011.08.011 -
Genetics Aug 1999A major finding within the field of archaea and molecular chaperones has been the demonstration that, while some species have the stress (heat-shock) gene hsp70(dnaK),... (Comparative Study)
Comparative Study Review
A major finding within the field of archaea and molecular chaperones has been the demonstration that, while some species have the stress (heat-shock) gene hsp70(dnaK), others do not. This gene encodes Hsp70(DnaK), an essential molecular chaperone in bacteria and eukaryotes. Due to the physiological importance and the high degree of conservation of this protein, its absence in archaeal organisms has raised intriguing questions pertaining to the evolution of the chaperone machine as a whole and that of its components in particular, namely, Hsp70(DnaK), Hsp40(DnaJ), and GrpE. Another archaeal paradox is that the proteins coded by these genes are very similar to bacterial homologs, as if the genes had been received via lateral transfer from bacteria, whereas the upstream flanking regions have no bacterial markers, but instead have typical archaeal promoters, which are like those of eukaryotes. Furthermore, the chaperonin system in all archaea studied to the present, including those that possess a bacterial-like chaperone machine, is similar to that of the eukaryotic-cell cytosol. Thus, two chaperoning systems that are designed to interact with a compatible partner, e.g., the bacterial chaperone machine physiologically interacts with the bacterial but not with the eucaryal chaperonins, coexist in archaeal cells in spite of their apparent functional incompatibility. It is difficult to understand how these hybrid characteristics of the archaeal chaperoning system became established and work, if one bears in mind the classical ideas learned from studying bacteria and eukaryotes. No doubt, archaea are intriguing organisms that offer an opportunity to find novel molecules and mechanisms that will, most likely, enhance our understanding of the stress response and the protein folding and refolding processes in the three phylogenetic domains.
Topics: Archaea; Archaeal Proteins; Bacterial Proteins; Escherichia coli Proteins; Evolution, Molecular; Genes, Archaeal; HSP40 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Heat-Shock Proteins; Macromolecular Substances; Molecular Chaperones; Protein Conformation; Protein Folding
PubMed: 10430558
DOI: 10.1093/genetics/152.4.1277 -
Trends in Pharmacological Sciences Nov 2014Normal cellular function is maintained by coordinated proteome machinery that performs a vast array of activities. Helping the proteome in such roles is the chaperome, a... (Review)
Review
Normal cellular function is maintained by coordinated proteome machinery that performs a vast array of activities. Helping the proteome in such roles is the chaperome, a network of molecular chaperones and folding enzymes. The stressed cell contains, at any time, a complex mixture of chaperome complexes; a majority performs 'housekeeping functions' similarly to non-stressed, normal cells, but a finely-tuned fraction buffers the proteome altered by chronic stress. The stress chaperome is epigenetically distinct from its normal, housekeeping counterpart, providing a basis for its selective targeting by small molecules. We discuss here the development of chaperome inhibitors, and how agents targeting chaperome members in stressed cells are in fact being directed towards chaperome complexes, and their effect is therefore determined by their ability to sample and engage such complexes. A new approach is needed to target and implement chaperome modulators in the investigation of diseases, and we propose that the classical thinking in drug discovery needs adjustment when developing chaperome-targeting drugs.
Topics: Animals; Heat-Shock Proteins; Humans; Models, Molecular; Molecular Chaperones; Molecular Targeted Therapy
PubMed: 25262919
DOI: 10.1016/j.tips.2014.09.001 -
Biochimica Et Biophysica Acta Sep 2015Plastids are a class of essential plant cell organelles comprising photosynthetic chloroplasts of green tissues, starch-storing amyloplasts of roots and tubers or the... (Review)
Review
Plastids are a class of essential plant cell organelles comprising photosynthetic chloroplasts of green tissues, starch-storing amyloplasts of roots and tubers or the colorful pigment-storing chromoplasts of petals and fruits. They express a few genes encoded on their organellar genome, called plastome, but import most of their proteins from the cytosol. The import into plastids, the folding of freshly-translated or imported proteins, the degradation or renaturation of denatured and entangled proteins, and the quality-control of newly folded proteins all require the action of molecular chaperones. Members of all four major families of ATP-dependent molecular chaperones (chaperonin/Cpn60, Hsp70, Hsp90 and Hsp100 families) have been identified in plastids from unicellular algae to higher plants. This review aims not only at giving an overview of the most current insights into the general and conserved functions of these plastid chaperones, but also into their specific plastid functions. Given that chloroplasts harbor an extreme environment that cycles between reduced and oxidized states, that has to deal with reactive oxygen species and is highly reactive to environmental and developmental signals, it can be presumed that plastid chaperones have evolved a plethora of specific functions some of which are just about to be discovered. Here, the most urgent questions that remain unsolved are discussed, and guidance for future research on plastid chaperones is given. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
Topics: Adenosine Triphosphate; HSP70 Heat-Shock Proteins; Molecular Chaperones; Oxidation-Reduction; Plastids; Protein Folding; Protein Transport
PubMed: 25596449
DOI: 10.1016/j.bbabio.2015.01.002 -
Future Medicinal Chemistry Jun 2013Hsp90 is a molecular chaperone and important driver of stabilization and activation of several oncogenic proteins that are involved in the malignant transformation of... (Review)
Review
Hsp90 is a molecular chaperone and important driver of stabilization and activation of several oncogenic proteins that are involved in the malignant transformation of tumor cells. Therefore, it is not surprising that Hsp90 has been reported to be a promising target for the treatment of several neoplasias, such as non-small-cell lung cancer and HER2-positive breast cancer. Hsp90 chaperone function depends on its ability to bind and hydrolyze ATP and Hsp90 inhibitors have been shown to compete with nucleotides for binding to Hsp90. Multiple factors, such as co-chaperones and post-translational modification, are involved in regulating Hsp90 ATPase activity. Here, the impact of post-translational modifications and co-chaperones on the efficacy of Hsp90 inhibitors are reviewed.
Topics: Acetylation; Animals; Cell Cycle Proteins; Chaperonins; Cyclophilins; HSP90 Heat-Shock Proteins; Homeodomain Proteins; Humans; Intramolecular Oxidoreductases; Molecular Chaperones; Phosphorylation; Prostaglandin-E Synthases; Protein Processing, Post-Translational; Tumor Suppressor Proteins
PubMed: 23734688
DOI: 10.4155/fmc.13.88 -
Cell Stress & Chaperones Jul 2016The ability of eukaryotes to adapt to an extreme range of temperatures is critically important for survival. Although adaptation to extreme high temperatures is well...
The ability of eukaryotes to adapt to an extreme range of temperatures is critically important for survival. Although adaptation to extreme high temperatures is well understood, reflecting the action of molecular chaperones, it is unclear whether these molecules play a role in survival at extremely low temperatures. The recent genome sequencing of the yeast Glaciozyma antarctica, isolated from Antarctic sea ice near Casey Station, provides an opportunity to investigate the role of molecular chaperones in adaptation to cold temperatures. We isolated a G. antarctica homologue of small heat shock protein 20 (HSP20), GaSGT1, and observed that the GaSGT1 mRNA expression in G. antarctica was markedly increased following culture exposure at low temperatures. Additionally, we demonstrated that GaSGT1 overexpression in Escherichia coli protected these bacteria from exposure to both high and low temperatures, which are lethal for growth. The recombinant GaSGT1 retained up to 60 % of its native luciferase activity after exposure to luciferase-denaturing temperatures. These results suggest that GaSGT1 promotes cell thermotolerance and employs molecular chaperone-like activity toward temperature assaults.
Topics: Amino Acid Sequence; Basidiomycota; Enzyme Assays; Escherichia coli; Fungal Proteins; Gene Expression Regulation, Fungal; Luciferases; Models, Molecular; Molecular Chaperones; RNA, Messenger; Sequence Analysis, Protein; Temperature; Thermotolerance
PubMed: 27154490
DOI: 10.1007/s12192-016-0696-2 -
Journal of Biomolecular NMR Jan 2021Advanced NMR methods combined with biophysical techniques have recently provided unprecedented insight into structure and dynamics of molecular chaperones and their...
Advanced NMR methods combined with biophysical techniques have recently provided unprecedented insight into structure and dynamics of molecular chaperones and their interaction with client proteins. These studies showed that several molecular chaperones are able to dissolve aggregation-prone polypeptides in aqueous solution. Furthermore, chaperone-bound clients often feature fluid-like backbone dynamics and chaperones have a denaturing effect on clients. Interestingly, these effects that chaperones have on client proteins resemble the effects of known chaotropic substances. Following this analogy, chaotropicity could be a fruitful concept to describe, quantify and rationalize molecular chaperone function. In addition, the observations raise the possibility that at least some molecular chaperones might share functional similarities with chaotropes. We discuss these concepts and outline future research in this direction.
Topics: Humans; Models, Molecular; Molecular Chaperones; Nuclear Magnetic Resonance, Biomolecular; Protein Binding; Protein Conformation; Protein Denaturation; Protein Folding; Protein Unfolding; Proteins; Solubility; Structure-Activity Relationship
PubMed: 33136251
DOI: 10.1007/s10858-020-00353-7 -
International Journal of Molecular... Aug 2019Proteins must fold into their native structure and maintain it during their lifespan to display the desired activity. To ensure proper folding and stability, and avoid... (Review)
Review
Proteins must fold into their native structure and maintain it during their lifespan to display the desired activity. To ensure proper folding and stability, and avoid generation of misfolded conformations that can be potentially cytotoxic, cells synthesize a wide variety of molecular chaperones that assist folding of other proteins and avoid their aggregation, which unfortunately is unavoidable under acute stress conditions. A protein machinery in metazoa, composed of representatives of the Hsp70, Hsp40, and Hsp110 chaperone families, can reactivate protein aggregates. We revised herein the phosphorylation sites found so far in members of these chaperone families and the functional consequences associated with some of them. We also discuss how phosphorylation might regulate the chaperone activity and the interaction of human Hsp70 with its accessory and client proteins. Finally, we present the information that would be necessary to decrypt the effect that post-translational modifications, and especially phosphorylation, could have on the biological activity of the Hsp70 system, known as the "chaperone code".
Topics: Animals; HSP70 Heat-Shock Proteins; Humans; Molecular Chaperones; Phosphorylation; Protein Aggregates; Protein Binding; Protein Folding; Structure-Activity Relationship
PubMed: 31450862
DOI: 10.3390/ijms20174122 -
Nature Communications Nov 2016Bacterial toxin-antitoxin (TA) systems, in which a labile antitoxin binds and inhibits the toxin, can promote adaptation and persistence by modulating bacterial growth...
Bacterial toxin-antitoxin (TA) systems, in which a labile antitoxin binds and inhibits the toxin, can promote adaptation and persistence by modulating bacterial growth in response to stress. Some atypical TA systems, known as tripartite toxin-antitoxin-chaperone (TAC) modules, include a molecular chaperone that facilitates folding and protects the antitoxin from degradation. Here we use a TAC module from Mycobacterium tuberculosis as a model to investigate the molecular mechanisms by which classical TAs can become 'chaperone-addicted'. The chaperone specifically binds the antitoxin at a short carboxy-terminal sequence (chaperone addiction sequence, ChAD) that is not present in chaperone-independent antitoxins. In the absence of chaperone, the ChAD sequence destabilizes the antitoxin, thus preventing toxin inhibition. Chaperone-ChAD pairs can be transferred to classical TA systems or to unrelated proteins and render them chaperone-dependent. This mechanism might be used to optimize the expression and folding of heterologous proteins in bacterial hosts for biotechnological or medical purposes.
Topics: Bacterial Proteins; Bacterial Toxins; Molecular Chaperones; Mycobacterium tuberculosis; Protein Folding; Recombinant Proteins; Toxin-Antitoxin Systems
PubMed: 27827369
DOI: 10.1038/ncomms13339