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Biological Chemistry Feb 2021Thiol-based redox switches evolved as efficient post-translational regulatory mechanisms that enable individual proteins to rapidly respond to sudden environmental... (Review)
Review
Thiol-based redox switches evolved as efficient post-translational regulatory mechanisms that enable individual proteins to rapidly respond to sudden environmental changes. While some protein functions need to be switched off to save resources and avoid potentially error-prone processes, protective functions become essential and need to be switched on. In this review, we focus on thiol-based activation mechanisms of stress-sensing chaperones. Upon stress exposure, these chaperones convert into high affinity binding platforms for unfolding proteins and protect cells against the accumulation of potentially toxic protein aggregates. Their chaperone activity is independent of ATP, a feature that becomes especially important under oxidative stress conditions, where cellular ATP levels drop and canonical ATP-dependent chaperones no longer operate. , reductive inactivation and substrate release require the restoration of ATP levels, which ensures refolding of client proteins by ATP-dependent foldases. We will give an overview over the different strategies that cells evolved to rapidly increase the pool of ATP-independent chaperones upon oxidative stress and provide mechanistic insights into how stress conditions are used to convert abundant cellular proteins into ATP-independent holding chaperones.
Topics: Molecular Chaperones; Oxidative Stress; Sulfhydryl Compounds
PubMed: 32990643
DOI: 10.1515/hsz-2020-0262 -
Biomedicines Oct 2021While protein refolding has been studied for over 50 years since the pioneering work of Christian Anfinsen, there have been a limited number of studies correlating...
While protein refolding has been studied for over 50 years since the pioneering work of Christian Anfinsen, there have been a limited number of studies correlating results between chemical, thermal, and mechanical unfolding. The limited knowledge of the relationship between these processes makes it challenging to compare results between studies if different refolding methods were applied. Our current work compares the energetic barriers and folding rates derived from chemical, thermal, and mechanical experiments using an immunoglobulin-like domain from the muscle protein titin as a model system. This domain, I83, has high solubility and low stability relative to other Ig domains in titin, though its stability can be modulated by calcium. Our experiments demonstrated that the free energy of refolding was equivalent with all three techniques, but the refolding rates exhibited differences, with mechanical refolding having slightly faster rates. This suggests that results from equilibrium-based measurements can be compared directly but care should be given comparing refolding kinetics derived from refolding experiments that used different unfolding methods.
PubMed: 34680512
DOI: 10.3390/biomedicines9101395 -
Cell Stress & Chaperones Jun 2024More than 99% of the mitochondrial proteome is encoded by the nucleus and requires refolding following import. Therefore, mitochondrial proteins require the coordinated... (Review)
Review
More than 99% of the mitochondrial proteome is encoded by the nucleus and requires refolding following import. Therefore, mitochondrial proteins require the coordinated action of molecular chaperones for their folding and activation. Several heat shock protein (Hsp) molecular chaperones, including members of the Hsp27, Hsp40/70, and Hsp90 families, as well as the chaperonin complex Hsp60/10 have an established role in mitochondrial protein import and folding. The "Chaperone Code" describes the regulation of chaperone activity by dynamic post-translational modifications; however, little is known about the post-translational regulation of mitochondrial chaperones. Dissecting the regulation of chaperone function is essential for understanding their differential regulation in pathogenic conditions and the potential development of efficacious therapeutic strategies. Here, we summarize the recent literature on post-translational regulation of mitochondrial chaperones, the consequences for mitochondrial function, and potential implications for disease.
Topics: Humans; Mitochondria; Molecular Chaperones; Mitochondrial Proteins; Animals; Protein Processing, Post-Translational; Heat-Shock Proteins; Protein Folding
PubMed: 38763405
DOI: 10.1016/j.cstres.2024.05.002 -
Science Advances Aug 2022SARS-CoV-2 cell entry is completed after viral spike (S) protein-mediated membrane fusion between viral and host cell membranes. Stable prefusion and postfusion S...
SARS-CoV-2 cell entry is completed after viral spike (S) protein-mediated membrane fusion between viral and host cell membranes. Stable prefusion and postfusion S structures have been resolved by cryo-electron microscopy and cryo-electron tomography, but the refolding intermediates on the fusion pathway are transient and have not been examined. We used an antiviral lipopeptide entry inhibitor to arrest S protein refolding and thereby capture intermediates as S proteins interact with hACE2 and fusion-activating proteases on cell-derived target membranes. Cryo-electron tomography imaged both extended and partially folded intermediate states of S2, as well as a novel late-stage conformation on the pathway to membrane fusion. The intermediates now identified in this dynamic S protein-directed fusion provide mechanistic insights that may guide the design of CoV entry inhibitors.
Topics: Angiotensin-Converting Enzyme 2; COVID-19; Cryoelectron Microscopy; Humans; SARS-CoV-2; Spike Glycoprotein, Coronavirus; Virus Internalization
PubMed: 35984891
DOI: 10.1126/sciadv.abo3153 -
Cells Sep 2020Protein homeostasis (proteostasis) disturbances and inflammation are evident in normal aging and some age-related neurodegenerative diseases. While the proteostasis... (Review)
Review
Protein homeostasis (proteostasis) disturbances and inflammation are evident in normal aging and some age-related neurodegenerative diseases. While the proteostasis network maintains the integrity of intracellular and extracellular functional proteins, inflammation is a biological response to harmful stimuli. Cellular stress conditions can cause protein damage, thus exacerbating protein misfolding and leading to an eventual overload of the degradation system. The regulation of proteostasis network is particularly important in postmitotic neurons due to their limited regenerative capacity. Therefore, maintaining balanced protein synthesis, handling unfolding, refolding, and degrading misfolded proteins are essential to preserve all cellular functions in the central nervous sysytem. Failing proteostasis may trigger inflammatory responses in glial cells, and the consequent release of inflammatory mediators may lead to disturbances in proteostasis. Here, we review the mechanisms of proteostasis and inflammatory response, emphasizing their role in the pathological hallmarks of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Furthermore, we discuss the interplay between proteostatic stress and excessive immune response that activates inflammation and leads to dysfunctional proteostasis.
Topics: Aging; Alzheimer Disease; Humans; Inflammation; Inflammation Mediators; Neurodegenerative Diseases; Parkinson Disease; Protein Biosynthesis; Protein Folding; Proteostasis; Proteostasis Deficiencies
PubMed: 32998318
DOI: 10.3390/cells9102183 -
Zhejiang Da Xue Xue Bao. Yi Xue Ban =... Nov 2022Molecular chaperones and co-chaperones facilitate the assembly of newly synthesized polypeptides and refolding of unfolded or misfolded proteins, thereby maintaining... (Review)
Review
Molecular chaperones and co-chaperones facilitate the assembly of newly synthesized polypeptides and refolding of unfolded or misfolded proteins, thereby maintaining protein homeostasis in cells. As co-chaperones of the master chaperone heat shock protein (HSP) 70, the HSP40 (DNAJ) proteins are largest chaperone family in eukaryotic cells. They contain a characteristic J-domain which mediates interaction with HSP70, thereby helping protein folding. It is well perceived that protein homeostasis is vital for neuronal health. DNAJ family proteins have been linked to the occurrence and progression of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, spinocerebellar ataxia, Charcot-Marie-Tooth disease, spinal muscular atrophy, distal hereditary motor neuropathy, limb-girdle type muscular dystrophy, neuronal ceroid lipofuscinosis and essential tremor in recent studies. DNAJA1 effectively degrades huntington aggregates; DNAJB1 can degrade protein aggregates ataxin-3; DNAJB2 can inhibit the formation of huntington aggregates; DNAJB6 can inhibit the aggregation of Aβ and α-synuclein; DNAJC5 can promote the release of TDP-43, τ protein, and α-synuclein into the extracellular space. Mutations in the essential tremor-associated DNAJC13 gene can prevent endosome protein trafficking. This article reviews the mechanism of DNAJ protein family in neurodegenerative diseases.
Topics: Humans; HSP40 Heat-Shock Proteins; alpha-Synuclein; Neurodegenerative Diseases; Essential Tremor; Protein Folding; Nerve Tissue Proteins; Molecular Chaperones
PubMed: 36581576
DOI: 10.3724/zdxbyxb-2021-0406 -
Biochemical Society Transactions Aug 2020The efficacy of superoxide dismutase-1 (SOD1) folding impacts neuronal loss in motor system neurodegenerative diseases. Mutations can prevent SOD1 post-translational... (Review)
Review
The efficacy of superoxide dismutase-1 (SOD1) folding impacts neuronal loss in motor system neurodegenerative diseases. Mutations can prevent SOD1 post-translational processing leading to misfolding and cytoplasmic aggregation in familial amyotrophic lateral sclerosis (ALS). Evidence of immature, wild-type SOD1 misfolding has also been observed in sporadic ALS, non-SOD1 familial ALS and Parkinson's disease. The copper chaperone for SOD1 (hCCS) is a dedicated and specific chaperone that assists SOD1 folding and maturation to produce the active enzyme. Misfolded or misfolding prone SOD1 also interacts with heat shock proteins and macrophage migration inhibitory factor to aid folding, refolding or degradation. Recognition of specific SOD1 structures by the molecular chaperone network and timely dissociation of SOD1-chaperone complexes are, therefore, important steps in SOD1 processing. Harnessing these interactions for therapeutic benefit is actively pursued as is the modulation of SOD1 behaviour with pharmacological and peptide chaperones. This review highlights the structural and mechanistic aspects of a selection of SOD1-chaperone interactions together with their impact on disease models.
Topics: Animals; Copper; Heat-Shock Proteins; Humans; Macrophage Migration-Inhibitory Factors; Molecular Chaperones; Mutation; Protein Folding; Superoxide Dismutase-1
PubMed: 32794552
DOI: 10.1042/BST20200318 -
Chemical Research in Toxicology Jul 2020Exposure to arsenic in contaminated drinking water is a worldwide public health problem that affects more than 200 million people. Protein quality control constitutes an... (Review)
Review
Exposure to arsenic in contaminated drinking water is a worldwide public health problem that affects more than 200 million people. Protein quality control constitutes an evolutionarily conserved mechanism for promoting proper folding of proteins, refolding of misfolded proteins, and removal of aggregated proteins, thereby maintaining homeostasis of the proteome (i.e., proteostasis). Accumulating lines of evidence from epidemiological and laboratory studies revealed that chronic exposure to inorganic arsenic species can elicit proteinopathies that contribute to neurodegenerative disorders, cancer, and type II diabetes. Here, we review the effects of arsenic exposure on perturbing various elements of the proteostasis network, including mitochondrial homeostasis, molecular chaperones, inflammatory response, ubiquitin-proteasome system, autophagy, as well as asymmetric segregation and axonal transport of misfolded proteins. We also discuss arsenic-induced disruptions of post-translational modifications of proteins, for example, ubiquitination, and their implications in proteostasis. Together, studies in the past few decades support that disruption of protein quality control may constitute an important mechanism underlying the arsenic-induced toxicity.
Topics: Animals; Arsenic; Humans; Protein Aggregates; Protein Folding; Protein Processing, Post-Translational; Proteins; Proteostasis
PubMed: 32410444
DOI: 10.1021/acs.chemrestox.0c00107 -
Biochimica Et Biophysica Acta.... Mar 2022Heat Shock Proteins (HSPs) and their co-chaperones have well-established roles in regulating proteostasis within the cell, the nature of which continues to emerge with... (Review)
Review
Heat Shock Proteins (HSPs) and their co-chaperones have well-established roles in regulating proteostasis within the cell, the nature of which continues to emerge with further study. To date, HSPs have been shown to be integral to protein folding and re-folding, protein transport, avoidance of protein aggregation, and modulation of protein degradation. Many cell signaling events are mediated by the chemical modification of proteins post-translationally that can alter protein conformation and activity, although it is not yet known whether the changes in protein conformation induced by post-translational modifications (PTMs) are also dependent upon HSPs and their co-chaperones for subsequent protein re-folding. We discuss what is known regarding roles for HSPs and other molecular chaperones in cell signaling events with a focus on oncogenic signaling. We also propose a hypothesis by which Hsp70 and Hsp90 may co-operate to facilitate cell signaling events that may link PTMs with the cellular protein folding machinery.
Topics: Animals; Heat-Shock Proteins; Humans; Molecular Chaperones; Neoplasms; Proteostasis; Signal Transduction
PubMed: 34906617
DOI: 10.1016/j.bbamcr.2021.119187 -
Applied Microbiology and Biotechnology Mar 2021Overexpression of recombinant proteins in Escherichia coli results in misfolded and non-active protein aggregates in the cytoplasm, so-called inclusion bodies (IB). In... (Review)
Review
Overexpression of recombinant proteins in Escherichia coli results in misfolded and non-active protein aggregates in the cytoplasm, so-called inclusion bodies (IB). In recent years, a change in the mindset regarding IBs could be observed: IBs are no longer considered an unwanted waste product, but a valid alternative to produce a product with high yield, purity, and stability in short process times. However, solubilization of IBs and subsequent refolding is necessary to obtain a correctly folded and active product. This protein refolding process is a crucial downstream unit operation-commonly done as a dilution in batch or fed-batch mode. Drawbacks of the state-of-the-art include the following: the large volume of buffers and capacities of refolding tanks, issues with uniform mixing, challenging analytics at low protein concentrations, reaction kinetics in non-usable aggregates, and generally low re-folding yields. There is no generic platform procedure available and a lack of robust control strategies. The introduction of Quality by Design (QbD) is the method-of-choice to provide a controlled and reproducible refolding environment. However, reliable online monitoring techniques to describe the refolding kinetics in real-time are scarce. In our view, only monitoring and control of re-folding kinetics can ensure a productive, scalable, and versatile platform technology for re-folding processes. For this review, we screened the current literature for a combination of online process analytical technology (PAT) and modeling techniques to ensure a controlled refolding process. Based on our research, we propose an integrated approach based on the idea that all aspects that cannot be monitored directly are estimated via digital twins and used in real-time for process control. KEY POINTS: • Monitoring and a thorough understanding of refolding kinetics are essential for model-based control of refolding processes. • The introduction of Quality by Design combining Process Analytical Technology and modeling ensures a robust platform for inclusion body refolding.
Topics: Inclusion Bodies; Kinetics; Protein Folding; Protein Refolding; Recombinant Proteins; Technology
PubMed: 33598720
DOI: 10.1007/s00253-021-11151-y