1
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Evaluation of Zn2+- and Cu2+-Binding Affinities of Native Cu,Zn-SOD1 and Its G93A Mutant by LC-ICP MS. Molecules 2022; 27:molecules27103160. [PMID: 35630637 PMCID: PMC9142952 DOI: 10.3390/molecules27103160] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 02/04/2023] Open
Abstract
The tight binding of Cu and Zn ions to superoxide dismutase 1 (SOD1) maintains the protein stability, associated with amyotrophic lateral sclerosis (ALS). Yet, the quantitative studies remain to be explored for the metal-binding affinity of wild-type SOD1 and its mutants. We have investigated the demetallation of Cu,Zn-SOD1 and its ALS-related G93A mutant in the presence of different standard metal ion chelators at varying temperatures by using an LC-ICP MS-based approach and fast size-exclusion chromatography. Our results showed that from the slow first-order kinetics both metal ions Zn2+ and Cu2+ were released simultaneously from the protein at elevated temperatures. The rate of the release depends on the concentration of chelating ligands but is almost independent of their metal-binding affinities. Similar studies with the G93A mutant of Cu,Zn-SOD1 revealed slightly faster metal-release. The demetallation of Cu,Zn-SOD1 comes always to completion, which hindered the calculation of the KD values. From the Arrhenius plots of the demetallation in the absence of chelators ΔH‡ = 173 kJ/mol for wt and 191 kJ/mol for G93A mutant Cu,Zn-SOD1 was estimated. Obtained high ΔH values are indicative of the occurrence of protein conformational changes before demetallation and we concluded that Cu,Zn-SOD1 complex is in native conditions kinetically inert. The fibrillization of both forms of SOD1 was similar.
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2
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Hsueh SCC, Nijland M, Peng X, Hilton B, Plotkin SS. First Principles Calculation of Protein-Protein Dimer Affinities of ALS-Associated SOD1 Mutants. Front Mol Biosci 2022; 9:845013. [PMID: 35402516 PMCID: PMC8988244 DOI: 10.3389/fmolb.2022.845013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 02/08/2022] [Indexed: 01/03/2023] Open
Abstract
Cu,Zn superoxide dismutase (SOD1) is a 32 kDa homodimer that converts toxic oxygen radicals in neurons to less harmful species. The dimerization of SOD1 is essential to the stability of the protein. Monomerization increases the likelihood of SOD1 misfolding into conformations associated with aggregation, cellular toxicity, and neuronal death in familial amyotrophic lateral sclerosis (fALS). The ubiquity of disease-associated mutations throughout the primary sequence of SOD1 suggests an important role of physicochemical processes, including monomerization of SOD1, in the pathology of the disease. Herein, we use a first-principles statistical mechanics method to systematically calculate the free energy of dimer binding for SOD1 using molecular dynamics, which involves sequentially computing conformational, orientational, and separation distance contributions to the binding free energy. We consider the effects of two ALS-associated mutations in SOD1 protein on dimer stability, A4V and D101N, as well as the role of metal binding and disulfide bond formation. We find that the penalty for dimer formation arising from the conformational entropy of disordered loops in SOD1 is significantly larger than that for other protein-protein interactions previously considered. In the case of the disulfide-reduced protein, this leads to a bound complex whose formation is energetically disfavored. Somewhat surprisingly, the loop free energy penalty upon dimerization is still significant for the holoprotein, despite the increased structural order induced by the bound metal cations. This resulted in a surprisingly modest increase in dimer binding free energy of only about 1.5 kcal/mol upon metalation of the protein, suggesting that the most significant stabilizing effects of metalation are on folding stability rather than dimer binding stability. The mutant A4V has an unstable dimer due to weakened monomer-monomer interactions, which are manifested in the calculation by a separation free energy surface with a lower barrier. The mutant D101N has a stable dimer partially due to an unusually rigid β-barrel in the free monomer. D101N also exhibits anticooperativity in loop folding upon dimerization. These computational calculations are, to our knowledge, the most quantitatively accurate calculations of dimer binding stability in SOD1 to date.
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Affiliation(s)
- Shawn C. C. Hsueh
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
| | - Mark Nijland
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
- Laboratory of Organic Chemistry, Wageningen University and Research, Wageningen, Netherlands
- Laboratory of Physical Chemistry and Soft Matter, Wageningen University and Research, Wageningen, Netherlands
| | - Xubiao Peng
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
- Center for Quantum Technology Research, School of Physics, Beijing Institute of Technology, Beijing, China
| | - Benjamin Hilton
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
- Imperial College London, London, United Kingdom
| | - Steven S. Plotkin
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada
- Genome Science and Technology Program, University of British Columbia, Vancouver, BC, Canada
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3
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Islam MN, Rauf A, Fahad FI, Emran TB, Mitra S, Olatunde A, Shariati MA, Rebezov M, Rengasamy KRR, Mubarak MS. Superoxide dismutase: an updated review on its health benefits and industrial applications. Crit Rev Food Sci Nutr 2021; 62:7282-7300. [PMID: 33905274 DOI: 10.1080/10408398.2021.1913400] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many short-lived and highly reactive oxygen species, such as superoxide anion (O2-) and hydrogen peroxide (H2O2), are toxic or can create oxidative stress in cells, a response involved in the pathogenesis of numerous diseases depending on their concentration, location, and cellular conditions. Superoxide dismutase (SOD) activities as an endogenous and exogenous cell defense mechanism include the potential use in treating various diseases, improving the potential use in treating various diseases, and improving food-stuffs preparation dietary supplements human nutrition. Published work indicates that SOD regulates oxidative stress, lipid metabolism, inflammation, and oxidation in cells. It can prevent lipid peroxidation, the oxidation of low-density lipoprotein in macrophages, lipid droplets' formation, and the adhesion of inflammatory cells into endothelial monolayers. It also expresses antioxidant effects in numerous cancer-related processes. Additionally, different forms of SOD may also augment food processing and pharmaceutical applications, exhibit anticancer, antioxidant, and anti-inflammatory effects, and prevent arterial problems by protecting the proliferation of vascular smooth muscle cells. Many investigations in this review have reported the therapeutic ability and physiological importance of SOD. Because of their antioxidative effects, SODs are of great potential in the medicinal, cosmetic, food, farming and chemical industries. This review discusses the findings of human and animal studies that support the advantages of SOD enzyme regulations to reduce the formation of oxidative stress in various ways.
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Affiliation(s)
- Mohammad Nazmul Islam
- Department of Pharmacy, International Islamic University Chittagong, Chittagong, Bangladesh
| | - Abdur Rauf
- Department of Chemistry, University of Swabi, Swabi, Pakistan
| | - Fowzul Islam Fahad
- Department of Pharmacy, International Islamic University Chittagong, Chittagong, Bangladesh
| | - Talha Bin Emran
- Department of Pharmacy, BGC Trust University Bangladesh, Chittagong, Bangladesh
| | - Saikat Mitra
- Faculty of Pharmacy, Department of Pharmacy, University of Dhaka, Dhaka, Bangladesh
| | - Ahmed Olatunde
- Department of Biochemistry, Abubakar Tafawa Balewa University, Bauchi, Nigeria
| | - Mohammad Ali Shariati
- K.G. Razumovsky Moscow State University of Technologies and Management (the First Cossack University), Moscow, Russian Federation
| | - Maksim Rebezov
- V.M. Gorbatov Federal Research Center for Food Systems of Russian Academy of Sciences, Moscow, Russian Federation.,Prokhorov General Physics Institute of the Russian Academy of Science, Moscow, Russian Federation
| | - Kannan R R Rengasamy
- Green Biotechnologies Research Centre of Excellence, University of Limpopo, Polokwane, South Africa
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4
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Bovio F, Sciandrone B, Urani C, Fusi P, Forcella M, Regonesi ME. Superoxide dismutase 1 (SOD1) and cadmium: A three models approach to the comprehension of its neurotoxic effects. Neurotoxicology 2021; 84:125-135. [PMID: 33774064 DOI: 10.1016/j.neuro.2021.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 12/13/2022]
Abstract
Cadmium (Cd) is a widespread toxic environmental contaminant, released by anthropogenic activities. It interferes with essential metal ions homeostasis and affects protein structures and functions by substituting zinc, copper and iron. In this study, the effect of cadmium on SOD1, a CuZn metalloenzyme catalyzing superoxide conversion into hydrogen peroxide, has been investigated in three different biological models. We first evaluated the effects of cadmium combined with copper and/or zinc on the recombinant GST-SOD1, expressed in E. coli BL21. The enzyme activity and expression were investigated in the presence of fixed copper and/or zinc doses with different cadmium concentrations, in the cellular medium. Cadmium caused a dose-dependent reduction in SOD1 activity, while the expression remains constant. Similar results were obtained in the cellular model represented by the human SH-SY5Y neuronal cell line. After cadmium treatment for 24 and 48 h, SOD1 enzymatic activity decreased in a dose- and time-dependent way, while the protein expression remained constant. Finally, a 16 h cadmium treatment caused a 25 % reduction of CuZn-SOD activity without affecting the protein expression in the Caenorhabditis elegans model. Taken together our results show an inhibitory effect of cadmium on SOD1 enzymatic activity, without affecting the protein expression, in all the biological models used, suggesting that cadmium can displace zinc from the enzyme catalytic site.
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Affiliation(s)
- Federica Bovio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126, Milan, Italy
| | - Barbara Sciandrone
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126, Milan, Italy
| | - Chiara Urani
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126, Milan, Italy; Integrated Models for Prevention and Protection in Environmental and Occupational Health, (MISTRAL), Interuniversity Research Center, Italy
| | - Paola Fusi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126, Milan, Italy; Integrated Models for Prevention and Protection in Environmental and Occupational Health, (MISTRAL), Interuniversity Research Center, Italy.
| | - Matilde Forcella
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126, Milan, Italy.
| | - Maria Elena Regonesi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza, 2, 20126, Milan, Italy; Milan Center of Neuroscience (NeuroMI), 20126, Milan, Italy
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5
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Cristóvão JS, Henriques BJ, Gomes CM. Biophysical and Spectroscopic Methods for Monitoring Protein Misfolding and Amyloid Aggregation. Methods Mol Biol 2019; 1873:3-18. [PMID: 30341600 DOI: 10.1007/978-1-4939-8820-4_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Proteins exhibit a remarkable structural plasticity and may undergo conformational changes resulting in protein misfolding both in a biological context and upon perturbing physiopathological conditions. Such nonfunctional protein conformers, including misfolded states and aggregates, are often associated to protein folding diseases. Understanding the biology of protein folding diseases thus requires tools that allow the structural characterization of nonnative conformations of proteins and their interconversions. Here we present detailed procedures to monitor protein conformational changes and aggregation based on spectroscopic and biophysical methods that include circular dichroism, ATR-Fourier-transformed infrared spectroscopy, fluorescence spectroscopy and dynamic light scattering. To illustrate the application of these methods we report to our previous studies on misfolding, aggregation and amyloid fibril formation by superoxide dismutase 1 (SOD1), a protein whose toxic deposition is implicated in the neurodegenerative disease amyotrophic lateral sclerosis (ALS).
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Affiliation(s)
- Joana S Cristóvão
- BioISI - Biosystems and Integrative Sciences Institute, Faculty of Sciences University of Lisbon, Lisbon, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences University of Lisbon, Lisbon, Portugal
| | - Bárbara J Henriques
- BioISI - Biosystems and Integrative Sciences Institute, Faculty of Sciences University of Lisbon, Lisbon, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences University of Lisbon, Lisbon, Portugal
| | - Cláudio M Gomes
- BioISI - Biosystems and Integrative Sciences Institute, Faculty of Sciences University of Lisbon, Lisbon, Portugal. .,Department of Chemistry and Biochemistry, Faculty of Sciences University of Lisbon, Lisbon, Portugal.
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6
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Pischedda A, Ramasamy KP, Mangiagalli M, Chiappori F, Milanesi L, Miceli C, Pucciarelli S, Lotti M. Antarctic marine ciliates under stress: superoxide dismutases from the psychrophilic Euplotes focardii are cold-active yet heat tolerant enzymes. Sci Rep 2018; 8:14721. [PMID: 30283056 PMCID: PMC6170424 DOI: 10.1038/s41598-018-33127-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 09/20/2018] [Indexed: 11/09/2022] Open
Abstract
Oxidative stress is a particularly severe threat to Antarctic marine polar organisms because they are exposed to high dissolved oxygen and to intense UV radiation. This paper reports the features of three superoxide dismutases from the Antarctic psychrophilic ciliate Euplotes focardii that faces two environmental challenges, oxidative stress and low temperature. Two out of these are Cu,Zn superoxide dismutases (named Ef-SOD1a and Ef-SOD1b) and one belongs to the Mn-containing group (Ef-SOD2). Ef-SOD1s and Ef-SOD2 differ in their evolutionary history, expression and overall structural features. Ef-SOD1 genes are expressed at different levels, with Ef-SOD1b mRNA 20-fold higher at the ciliate optimal temperature of growth (4 °C). All Ef-SOD enzymes are active at 4 °C, consistent with the definition of cold-adapted enzymes. At the same time, they display temperatures of melting in the range 50-70 °C and retain residual activity after incubation at 65-75 °C. Supported by data of molecular dynamics simulation, we conclude that the E. focardii SODs combine cold activity, local molecular flexibility and thermo tolerance.
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Affiliation(s)
- Alessandro Pischedda
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126, Milano, Italy
| | - Kesava Priyan Ramasamy
- School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 1, 62032, Camerino (MC), Italy
| | - Marco Mangiagalli
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126, Milano, Italy
| | | | | | - Cristina Miceli
- School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 1, 62032, Camerino (MC), Italy
| | - Sandra Pucciarelli
- School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 1, 62032, Camerino (MC), Italy.
| | - Marina Lotti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126, Milano, Italy
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7
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Santur KB, Sevenich MM, Schwarten M, Nischwitz V, Willbold D, Mohrlüder J. In Vitro Reconstitution of the Highly Active and Natively Folded Recombinant Human Superoxide Dismutase 1 Holoenzyme. ChemistrySelect 2018. [DOI: 10.1002/slct.201801319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Karoline B. Santur
- Institute of Complex Systems (ICS-6)Forschungszentrum Jülich Germany
- Institut für Physikalische BiologieHeinrich-Heine-Universität Düsseldorf Germany
| | - Marc M. Sevenich
- Institute of Complex Systems (ICS-6)Forschungszentrum Jülich Germany
- Institut für Physikalische BiologieHeinrich-Heine-Universität Düsseldorf Germany
| | - Melanie Schwarten
- Institute of Complex Systems (ICS-6)Forschungszentrum Jülich Germany
| | - Volker Nischwitz
- Central Institute for Engineering, Electronics and Analytics (ZEA-3)Forschungszentrum Jülich Germany
| | - Dieter Willbold
- Institute of Complex Systems (ICS-6)Forschungszentrum Jülich Germany
- Institut für Physikalische BiologieHeinrich-Heine-Universität Düsseldorf Germany
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8
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Production of Human Cu,Zn SOD with Higher Activity and Lower Toxicity in E. coli via Mutation of Free Cysteine Residues. BIOMED RESEARCH INTERNATIONAL 2017; 2017:4817376. [PMID: 28299326 PMCID: PMC5337334 DOI: 10.1155/2017/4817376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/13/2016] [Accepted: 01/24/2017] [Indexed: 11/17/2022]
Abstract
Although, as an antioxidant enzyme, human Cu,Zn superoxide dismutase 1 (hSOD1) can mitigate damage to cell components caused by free radicals generated by aerobic metabolism, large-scale manufacturing and clinical use of hSOD1 are still limited by the challenge of rapid and inexpensive production of high-quality eukaryotic hSOD1 in recombinant forms. We have demonstrated previously that it is a promising strategy to increase the expression levels of soluble hSOD1 so as to increase hSOD1 yields in E. coli. In this study, a wild-type hSOD1 (wtSOD1) and three mutant SOD1s (mhSOD1s), in which free cysteines were substituted with serine, were constructed and their expression in soluble form was measured. Results show that the substitution of Cys111 (mhSOD1/C111S) increased the expression of soluble hSOD1 in E. coli whereas substitution of the internal Cys6 (mhSOD1/C6S) decreased it. Besides, raised levels of soluble expression led to an increase in hSOD1 yields. In addition, mhSOD1/C111S expressed at a higher soluble level showed lower toxicity and stronger whitening and antiradiation activities than those of wtSOD1. Taken together, our data demonstrate that C111S mutation in hSOD1 is an effective strategy to develop new SOD1-associated reagents and that mhSOD1/C111S is a satisfactory candidate for large-scale production.
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9
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Eiamphungporn W, Yainoy S, Prachayasittikul V. Enhancement of Solubility and Specific Activity of a Cu/Zn Superoxide Dismutase by Co-expression with a Copper Chaperone in Escherichia coli. IRANIAN JOURNAL OF BIOTECHNOLOGY 2016; 14:243-249. [PMID: 28959342 PMCID: PMC5434994 DOI: 10.15171/ijb.1465] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Human Cu/Zn superoxide dismutase (hSOD1) is an antioxidant enzyme with potential as a therapeutic agent. However, heterologous expression of hSOD1 has remained an issue due to Cu2+ insufficiency at protein active site, leading to low solubility and enzymatic activity. OBJECTIVES The effect of co-expressed human copper chaperone (hCCS) to enhance the solubility and enzymatic activity of hSOD1 in E. coli was investigated in the presence and absence of Cu2+. MATERIALS AND METHODS pETDuet-1-hSOD1 and pETDuet-1-hCCS-hSOD1 were constructed and individually transformed into E. coli strain BL21(DE3). The recombinant hSOD1 was expressed and purified using immobilized metal affinity chromatography. The yield and specific activity of hSOD1 in all conditions were studied. RESULTS Co-expression with hCCS increased hSOD1 solubility at 37°C, but this effect was not observed at 25°C. Notably, the specific activity of hSOD1 was enhanced by 1.5 fold and greater than 3 fold when co-expressed with hCCS at 25°C with and without Cu2+ supplement, respectively. However, the chaperone co-expression did not significantly increase the yield of hSOD1 comparable to the expression of hSOD1 alone. CONCLUSIONS This study is the first report demonstrating a potential use of hCCS for heterologous production of hSOD1 with high enzymatic activity.
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Affiliation(s)
- Warawan Eiamphungporn
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand
| | - Sakda Yainoy
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.,Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand
| | - Virapong Prachayasittikul
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand
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10
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Kim S, Kim HY, Kim JH, Choi JH, Ham WK, Jeon YJ, Kang H, Kim TY. Enhancement of potency and stability of human extracellular superoxide dismutase. BMB Rep 2015; 48:91-6. [PMID: 24856831 PMCID: PMC4352618 DOI: 10.5483/bmbrep.2015.48.2.093] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Indexed: 01/13/2023] Open
Abstract
Cells express several antioxidant enzymes to scavenge reactive oxygen species (ROS) responsible for oxidative damages and various human diseases. Therefore, antioxidant enzymes are considered biomedicine candidates. Among them, extracellular superoxide dismutase (SOD3) had showed prominent efficacy against asthma and inflammation. Despite its advantages as a biomedicine, the difficulty in obtaining large quantity of active recombinant human SOD3 (rhSOD3) has limited its clinical applications. We found that a significant fraction of overexpressed rhSOD3 was composed of the inactive apo-enzyme and its potency against inflammation depended on the rate of metal incorporation. Also, purified rhSOD3 was unstable and lost its activity very quickly. Here, we suggest an ideal preparative method to express, purify, and store highly active rhSOD3. The enzymatic activity of rhSOD3 was maximized by incorporating metal ions into rhSOD3 after purification. Also, albumin or polyethylene glycol prevented rapid inactivation or degradation of rhSOD3 during preparative procedures and long-term storage.
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Affiliation(s)
- Sunghwan Kim
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040; New Drug Development Center, Daegu-Gyungpook Medical Innovation Foundation, Daegu 701-310, Korea
| | - Hae-Young Kim
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
| | - Jung-Ho Kim
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
| | - Jung-Hye Choi
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
| | - Won-Kook Ham
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
| | - Yoon-Jae Jeon
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
| | - Hara Kang
- Division of Life Science, College of Life Science and Bioengineering, Incheon National University, Incheon 406-772, Korea
| | - Tae-Yoon Kim
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul 137-040, Korea
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11
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Leal SS, Cristóvão JS, Biesemeier A, Cardoso I, Gomes CM. Aberrant zinc binding to immature conformers of metal-free copper-zinc superoxide dismutase triggers amorphous aggregation. Metallomics 2015; 7:333-46. [PMID: 25554447 DOI: 10.1039/c4mt00278d] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Superoxide dismutase 1 (SOD1) is a Cu/Zn metalloenzyme that aggregates in amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. Correct metal insertion during SOD1 biosynthesis is critical to prevent misfolding; however Zn(2+) can bind to the copper-site leading to an aberrantly metallated protein. These effects of Zn(2+) misligation on SOD1 aggregation remain to be explored, even though Zn(2+) levels are upregulated in ALS motor neurons. Here we use complementary biophysical methods to investigate Zn(2+) binding and its effects on the aggregation of three immature metal-free SOD1 conformers that represent biogenesis intermediates: dimeric, monomeric and reduced monomeric SOD1. Using isothermal titration calorimetry we determined that Zn(2+) binds to all conformers both at the zinc- as well as to the copper-site; however Zn(2+) binding mechanisms to the zinc-site have distinct characteristics across immature conformers. We show that this 'zinc overload' of immature SOD1 promotes intermolecular interactions, as evidenced by dynamic light scattering and ThT fluorescence kinetic studies. Analysis of aged zinc-induced aggregates by energy-dispersive X-ray and electron energy-loss spectroscopy shows that aggregates integrate some Zn(2+). In addition, electron diffraction analysis identifies nano-scaled crystalline materials and amyloid fibril-like reflections. Transmission electron microscopy reveals that Zn(2+) diverts the SOD1 aggregation pathway from fibrils to amorphous aggregate, and electrophoretic analysis evidences an increase in insoluble materials. Overall, we provide evidence that aberrant zinc coordination to immature conformers broadens the population of SOD1 misfolded species at early aggregation stages and provide evidence for a high structural polymorphism and heterogeneity of SOD1 aggregates.
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Affiliation(s)
- Sónia S Leal
- Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
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12
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Hennig J, Andrésen C, Museth AK, Lundström P, Tibell LAE, Jonsson BH. Local Destabilization of the Metal-Binding Region in Human Copper–Zinc Superoxide Dismutase by Remote Mutations Is a Possible Determinant for Progression of ALS. Biochemistry 2015; 54:323-33. [DOI: 10.1021/bi500606j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Janosch Hennig
- Division
of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
- Institute
of Structural Biology, Helmholtz Zentrum München GmbH, DE-85764 Neuherberg, Germany
- Chair
of Biomolecular NMR Spectroscopy, Department of Chemistry, Technische Universität München, DE-85748 Garching, Germany
| | - Cecilia Andrésen
- Division
of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
| | - A. Katrine Museth
- Division
of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
- Division
of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Patrik Lundström
- Division
of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
| | - Lena A. E. Tibell
- Department
of Science and Technology, Linköping University, SE-601 74, Norrköping, Sweden
| | - Bengt-Harald Jonsson
- Division
of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
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13
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Estácio SG, Leal SS, Cristóvão JS, Faísca PFN, Gomes CM. Calcium binding to gatekeeper residues flanking aggregation-prone segments underlies non-fibrillar amyloid traits in superoxide dismutase 1 (SOD1). BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:118-26. [PMID: 25463043 DOI: 10.1016/j.bbapap.2014.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/14/2014] [Accepted: 11/18/2014] [Indexed: 12/26/2022]
Abstract
Calcium deregulation is a central feature among neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Calcium accumulates in the spinal and brain stem motor neurons of ALS patients triggering multiple pathophysiological processes which have been recently shown to include direct effects on the aggregation cascade of superoxide dismutase 1 (SOD1). SOD1 is a Cu/Zn enzyme whose demetallated form is implicated in ALS protein deposits, contributing to toxic gain of function phenotypes. Here we undertake a combined experimental and computational study aimed at establishing the molecular details underlying the regulatory effects of Ca(2+) over SOD1 aggregation potential. Isothermal titration calorimetry indicates entropy driven low affinity association of Ca(2+) ions to apo SOD1, at pH7.5 and 37°C. Molecular dynamics simulations denote a noticeable loss of native structure upon Ca(2+) association that is especially prominent at the zinc-binding and electrostatic loops, whose decoupling is known to expose the central SOD1 β-barrel triggering aggregation. Structural mapping of the preferential apo SOD1 Ca(2+) binding locations reveals that among the most frequent ligands for Ca(2+) are negatively-charged gatekeeper residues located in boundary positions with respect to segments highly prone to edge-to-edge aggregation. Calcium interactions thus diminish gatekeeping roles of these residues, by shielding repulsive interactions via stacking between aggregating β-sheets, partly blocking fibril formation and promoting amyloidogenic oligomers such as those found in ALS inclusions. Interestingly, many fALS mutations occur at these positions, disclosing how Ca(2+) interactions recreate effects similar to those of genetic defects, a finding with relevance to understand sporadic ALS pathomechanisms.
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Affiliation(s)
- Sílvia G Estácio
- Centro de Física da Matéria Condensada, Universidade de Lisboa, Lisboa, Portugal; Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
| | - Sónia S Leal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Joana S Cristóvão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Patrícia F N Faísca
- Centro de Física da Matéria Condensada, Universidade de Lisboa, Lisboa, Portugal; Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal.
| | - Cláudio M Gomes
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal.
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Aggregation propensities of superoxide dismutase G93 hotspot mutants mirror ALS clinical phenotypes. Proc Natl Acad Sci U S A 2014; 111:E4568-76. [PMID: 25316790 DOI: 10.1073/pnas.1308531111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Protein framework alterations in heritable Cu, Zn superoxide dismutase (SOD) mutants cause misassembly and aggregation in cells affected by the motor neuron disease ALS. However, the mechanistic relationship between superoxide dismutase 1 (SOD1) mutations and human disease is controversial, with many hypotheses postulated for the propensity of specific SOD mutants to cause ALS. Here, we experimentally identify distinguishing attributes of ALS mutant SOD proteins that correlate with clinical severity by applying solution biophysical techniques to six ALS mutants at human SOD hotspot glycine 93. A small-angle X-ray scattering (SAXS) assay and other structural methods assessed aggregation propensity by defining the size and shape of fibrillar SOD aggregates after mild biochemical perturbations. Inductively coupled plasma MS quantified metal ion binding stoichiometry, and pulsed dipolar ESR spectroscopy evaluated the Cu(2+) binding site and defined cross-dimer copper-copper distance distributions. Importantly, we find that copper deficiency in these mutants promotes aggregation in a manner strikingly consistent with their clinical severities. G93 mutants seem to properly incorporate metal ions under physiological conditions when assisted by the copper chaperone but release copper under destabilizing conditions more readily than the WT enzyme. Altered intradimer flexibility in ALS mutants may cause differential metal retention and promote distinct aggregation trends observed for mutant proteins in vitro and in ALS patients. Combined biophysical and structural results test and link copper retention to the framework destabilization hypothesis as a unifying general mechanism for both SOD aggregation and ALS disease progression, with implications for disease severity and therapeutic intervention strategies.
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Cristóvão JS, Leal SS, Cardoso I, Gomes CM. Small molecules present in the cerebrospinal fluid metabolome influence superoxide dismutase 1 aggregation. Int J Mol Sci 2013; 14:19128-45. [PMID: 24048249 PMCID: PMC3794824 DOI: 10.3390/ijms140919128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 08/28/2013] [Accepted: 08/30/2013] [Indexed: 12/13/2022] Open
Abstract
Superoxide dismutase 1 (SOD1) aggregation is one of the pathological markers of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. The underlying molecular grounds of SOD1 pathologic aggregation remains obscure as mutations alone are not exclusively the cause for the formation of protein inclusions. Thus, other components in the cell environment likely play a key role in triggering SOD1 toxic aggregation in ALS. Recently, it was found that ALS patients present a specific altered metabolomic profile in the cerebrospinal fluid (CSF) where SOD1 is also present and potentially interacts with metabolites. Here we have investigated how some of these small molecules affect apoSOD1 structure and aggregation propensity. Our results show that as co-solvents, the tested small molecules do not affect apoSOD1 thermal stability but do influence its tertiary interactions and dynamics, as evidenced by combined biophysical analysis and proteolytic susceptibility. Moreover, these compounds influence apoSOD1 aggregation, decreasing nucleation time and promoting the formation of larger and less soluble aggregates, and in some cases polymeric assemblies apparently composed by spherical species resembling the soluble native protein. We conclude that some components of the ALS metabolome that shape the chemical environment in the CSF may influence apoSOD1 conformers and aggregation.
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Affiliation(s)
- Joana S. Cristóvão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras 2784-505, Portugal; E-Mails: (J.S.C.); (S.S.L.)
| | - Sónia S. Leal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras 2784-505, Portugal; E-Mails: (J.S.C.); (S.S.L.)
| | - Isabel Cardoso
- Molecular Neurobiology Unit, Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, Porto 4150-180, Portugal; E-Mail:
- Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Rua Valente Perfeito, 322, Vila Nova de Gaia 4400-330, Portugal
| | - Cláudio M. Gomes
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras 2784-505, Portugal; E-Mails: (J.S.C.); (S.S.L.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +351-21-446-9332; Fax: +351-21-441-1277
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Leal SS, Cardoso I, Valentine JS, Gomes CM. Calcium ions promote superoxide dismutase 1 (SOD1) aggregation into non-fibrillar amyloid: a link to toxic effects of calcium overload in amyotrophic lateral sclerosis (ALS)? J Biol Chem 2013; 288:25219-25228. [PMID: 23861388 DOI: 10.1074/jbc.m113.470740] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Imbalance in metal ion homeostasis is a hallmark in neurodegenerative conditions involving protein deposition, and amyotrophic lateral sclerosis (ALS) is no exception. In particular, Ca(2+) dysregulation has been shown to correlate with superoxide dismutase-1 (SOD1) aggregation in a cellular model of ALS. Here we present evidence that SOD1 aggregation is enhanced and modulated by Ca(2+). We show that at physiological pH, Ca(2+) induces conformational changes that increase SOD1 β-sheet content, as probed by far UV CD and attenuated total reflectance-FTIR, and enhances SOD1 hydrophobicity, as probed by ANS fluorescence emission. Moreover, dynamic light scattering analysis showed that Ca(2+) boosts the onset of SOD1 aggregation. In agreement, Ca(2+) decreases SOD1 critical concentration and nucleation time during aggregation kinetics, as evidenced by thioflavin T fluorescence emission. Attenuated total reflectance FTIR analysis showed that Ca(2+) induced aggregates consisting preferentially of antiparallel β-sheets, thus suggesting a modulation effect on the aggregation pathway. Transmission electron microscopy and analysis with conformational anti-fibril and anti-oligomer antibodies showed that oligomers and amyloidogenic aggregates constitute the prevalent morphology of Ca(2+)-induced aggregates, thus indicating that Ca(2+) diverts SOD1 aggregation from fibrils toward amorphous aggregates. Interestingly, the same heterogeneity of conformations is found in ALS-derived protein inclusions. We thus hypothesize that transient variations and dysregulation of cellular Ca(2+) levels contribute to the formation of SOD1 aggregates in ALS patients. In this scenario, Ca(2+) may be considered as a pathogenic effector in the formation of ALS proteinaceous inclusions.
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Affiliation(s)
- Sónia S Leal
- From the Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. República 127, 2780-756 Oeiras, Portugal
| | - Isabel Cardoso
- the Molecular Neurobiology Unit, Instituto Biologia Molecular e Celular, 4150-180 Porto, Portugal, and
| | - Joan S Valentine
- the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095
| | - Cláudio M Gomes
- From the Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. República 127, 2780-756 Oeiras, Portugal,.
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Botelho HM, Leal SS, Cardoso I, Yanamandra K, Morozova-Roche LA, Fritz G, Gomes CM. S100A6 amyloid fibril formation is calcium-modulated and enhances superoxide dismutase-1 (SOD1) aggregation. J Biol Chem 2012; 287:42233-42. [PMID: 23076148 DOI: 10.1074/jbc.m112.396416] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
S100A6 is a small EF-hand calcium- and zinc-binding protein involved in the regulation of cell proliferation and cytoskeletal dynamics. It is overexpressed in neurodegenerative disorders and a proposed marker for Amyotrophic Lateral Sclerosis (ALS). Following recent reports of amyloid formation by S100 proteins, we investigated the aggregation properties of S100A6. Computational analysis using aggregation predictors Waltz and Zyggregator revealed increased propensity within S100A6 helices H(I) and H(IV). Subsequent analysis of Thioflavin-T binding kinetics under acidic conditions elicited a very fast process with no lag phase and extensive formation of aggregates and stacked fibrils as observed by electron microscopy. Ca(2+) exerted an inhibitory effect on the aggregation kinetics, which could be reverted upon chelation. An FT-IR investigation of the early conformational changes occurring under these conditions showed that Ca(2+) promotes anti-parallel β-sheet conformations that repress fibrillation. At pH 7, Ca(2+) rendered the fibril formation kinetics slower: time-resolved imaging showed that fibril formation is highly suppressed, with aggregates forming instead. In the absence of metals an extensive network of fibrils is formed. S100A6 oligomers, but not fibrils, were found to be cytotoxic, decreasing cell viability by up to 40%. This effect was not observed when the aggregates were formed in the presence of Ca(2+). Interestingly, native S1006 seeds SOD1 aggregation, shortening its nucleation process. This suggests a cross-talk between these two proteins involved in ALS. Overall, these results put forward novel roles for S100 proteins, whose metal-modulated aggregation propensity may be a key aspect in their physiology and function.
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Affiliation(s)
- Hugo M Botelho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
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18
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Zetterström P, Graffmo KS, Andersen PM, Brännström T, Marklund SL. Proteins that bind to misfolded mutant superoxide dismutase-1 in spinal cords from transgenic amyotrophic lateral sclerosis (ALS) model mice. J Biol Chem 2011; 286:20130-6. [PMID: 21493711 DOI: 10.1074/jbc.m111.218842] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutant superoxide dismutase-1 (SOD1) has an unidentified toxic property that provokes ALS. Several ALS-linked SOD1 mutations cause long C-terminal truncations, which suggests that common cytotoxic SOD1 conformational species should be misfolded and that the C-terminal end cannot be involved. The cytotoxicity may arise from interaction of cellular proteins with misfolded SOD1 species. Here we specifically immunocaptured misfolded SOD1 by the C-terminal end, from extracts of spinal cords from transgenic ALS model mice. Associated proteins were identified with proteomic techniques. Two transgenic models expressing SOD1s with contrasting molecular properties were examined: the stable G93A mutant, which is abundant in the spinal cord with only a tiny subfraction misfolded, and the scarce disordered truncation mutant G127insTGGG. For comparison, proteins in spinal cord extracts with affinity for immobilized apo G93A mutant SOD1 were determined. Two-dimensional gel patterns with a limited number of bound proteins were found, which were similar for the two SOD1 mutants. Apart from neurofilament light, the proteins identified were all chaperones and by far most abundant was Hsc70. The immobilized apo G93A SOD1, which would populate a variety of conformations, was found to bind to a considerable number of additional proteins. A substantial proportion of the misfolded SOD1 in the spinal cord extracts appeared to be chaperone-associated. Still, only about 1% of the Hsc70 appeared to be associated with misfolded SOD1. The results argue against the notion that chaperone depletion is involved in ALS pathogenesis in the transgenic models and in humans carrying SOD1 mutations.
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Affiliation(s)
- Per Zetterström
- Department of Medical Biosciences, Clinical Chemistry, Umeå University, SE-901 85 Umeå, Sweden
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Bafana A, Dutt S, Kumar S, Ahuja PS. Superoxide dismutase: an industrial perspective. Crit Rev Biotechnol 2010; 31:65-76. [DOI: 10.3109/07388551.2010.490937] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Museth AK, Brorsson AC, Lundqvist M, Tibell LAE, Jonsson BH. The ALS-associated mutation G93A in human copper-zinc superoxide dismutase selectively destabilizes the remote metal binding region. Biochemistry 2009; 48:8817-29. [PMID: 19655787 DOI: 10.1021/bi900703v] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
More than 100 distinct mutations in the gene (SOD1) for human copper-zinc superoxide dismutase (CuZnSOD) have been associated with familial amyotrophic lateral sclerosis (fALS). Studies of these mutant proteins, which often have been performed under far from physiological conditions, have indicated effects on protein stabilities, catalytic activity, and metal binding affinities but with no common pattern. Also, with the knowledge that ALS is a late onset disease it is apparent that protein interactions which contribute to the disorder might, in the natural cellular milieu, depend on a delicate balance between intrinsic protein properties. In this study, we have used experimental conditions as near as possible to the in vivo conditions to reduce artifacts emanating from the experimental setup. Using 1H-15N HSQC NMR spectroscopy, we have analyzed hydrogen exchange at the amide groups of wild-type (wt) CuZnSOD and the fALS-associated G93A SOD variant in their fully metalated states. From analyses of the exchange pattern, we have characterized the local dynamics at 64% of all positions in detail in both the wt and G93A protein. The results show that the G93A mutation had no effect on the dynamics at a majority of the investigated positions. However, the mutation results in local destabilization at the site of the mutation and also in stabilization at a few positions that were apparently scattered over the entire protein surface. Most remarkably, the mutation selectively destabilized the remote metal binding region. The results indicate that the metal binding region may affect the intermolecular protein-protein interactions which cause formation of protein aggregates.
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Affiliation(s)
- Anna Katrine Museth
- Division of Molecular Biotechnology, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden
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21
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Functional features cause misfolding of the ALS-provoking enzyme SOD1. Proc Natl Acad Sci U S A 2009; 106:9667-72. [PMID: 19497878 DOI: 10.1073/pnas.0812046106] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structural integrity of the ubiquitous enzyme superoxide dismutase (SOD1) relies critically on the correct coordination of Cu and Zn. Loss of these cofactors not only promotes SOD1 aggregation in vitro but also seems to be a key prerequisite for pathogenic misfolding in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). We examine here the consequences of Zn(2+) loss by selectively removing the Zn site, which has been implicated as the main modulator of SOD1 stability and disease competence. After Zn-site removal, the remaining Cu ligands can coordinate a nonnative Zn(2+) ion with microM affinity in the denatured state, and then retain this ion throughout the folding reaction. Without the restriction of a metallated Zn site, however, the Cu ligands fail to correctly coordinate the nonnative Zn(2+) ion: Trapping of a water molecule causes H48 to change rotamer and swing outwards. The misligation is sterically incompatible with the native structure. As a consequence, SOD1 unfolds locally and interacts with neighboring molecules in the crystal lattice. The findings point to a critical role for the native Zn site in controlling SOD1 misfolding, and show that even subtle changes of the metal-loading sequence can render the wild-type protein the same structural properties as ALS-provoking mutations. This frustrated character of the SOD1 molecule seems to arise from a compromise between optimization of functional and structural features.
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Zetterström P, Stewart HG, Bergemalm D, Jonsson PA, Graffmo KS, Andersen PM, Brännström T, Oliveberg M, Marklund SL. Soluble misfolded subfractions of mutant superoxide dismutase-1s are enriched in spinal cords throughout life in murine ALS models. Proc Natl Acad Sci U S A 2007; 104:14157-62. [PMID: 17715066 PMCID: PMC1955813 DOI: 10.1073/pnas.0700477104] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutants of superoxide dismutase-1 (SOD1) cause ALS by an unidentified cytotoxic mechanism. We have previously shown that the stable SOD1 mutants D90A and G93A are abundant and show the highest levels in liver and kidney in transgenic murine ALS models, whereas the unstable G85R and G127X mutants are scarce but enriched in the CNS. These data indicated that minute amounts of misfolded SOD1 enriched in the motor areas might exert the ALS-causing cytotoxicity. A hydrophobic interaction chromatography (HIC) protocol was developed with the aim to determine the abundance of soluble misfolded SOD1 in tissues in vivo. Most G85R and G127X mutant SOD1s bound in the assay, but only minute subfractions of the D90A and G93A mutants. The absolute levels of HIC-binding SOD1 were, however, similar and broadly inversely related to lifespans in the models. They were generally enriched in the susceptible spinal cord. The HIC-binding SOD1 was composed of disulfide-reduced subunits lacking metal ions and also subunits that apparently carried nonnative intrasubunit disulfide bonds. The levels were high from birth until death and were comparable to the amounts of SOD1 that become sequestered in aggregates in the terminal stage. The HIC-binding SOD1 species ranged from monomeric to trimeric in size. These species form a least common denominator amongst SOD1 mutants with widely different molecular characteristics and might be involved in the cytotoxicity that causes ALS.
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Affiliation(s)
| | - Heather G. Stewart
- Departments of *Medical Biosciences
- Pharmacology and Clinical Neuroscience, Umeå University, SE-901 85 Umeå, Sweden
- Brain Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 1Z4; and
| | | | | | | | - Peter M. Andersen
- Departments of *Medical Biosciences
- Pharmacology and Clinical Neuroscience, Umeå University, SE-901 85 Umeå, Sweden
| | | | - Mikael Oliveberg
- Department of Biochemistry and Biophysics, the Arrhenius Laboratory for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Stefan L. Marklund
- Departments of *Medical Biosciences
- Clinical Chemistry and
- **To whom correspondence should be addressed. E-mail:
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Hörnberg A, Logan DT, Marklund SL, Oliveberg M. The coupling between disulphide status, metallation and dimer interface strength in Cu/Zn superoxide dismutase. J Mol Biol 2006; 365:333-42. [PMID: 17070542 DOI: 10.1016/j.jmb.2006.09.048] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/05/2006] [Accepted: 09/19/2006] [Indexed: 11/26/2022]
Abstract
The gain of neurotoxic function in amyotrophic lateral sclerosis (ALS) has been linked to misfolding of the homodimeric enzyme Cu/Zn superoxide dismutase (SOD). Here, we present the crystal structure of fully cysteine-depleted human SOD (SOD(CallA)), representing a reduced, marginally stable intermediate on the folding pathway in vivo that has also been implicated as neurotoxic precursor state. A hallmark of this species is that it fails to dimerize and becomes trapped as a monomer in the absence of the active-site metals. The crystallographic data show that removal of the C57-C146 disulphide bond sets free the interface loop IV in the apo protein, whereas the same loop remains unaffected in the holo protein. Thus, the low dimerisation propensity of disulphide-reduced apoSOD seems to be of entropic origin due to increased loop flexibility in the monomeric state: in the disulphide-reduced holo protein this gain in configurational entropy upon splitting of the dimer interface is reduced by the metal coordination.
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Affiliation(s)
- Andreas Hörnberg
- Department of Biochemistry, Umeå University, SE-901 87 Umeå, Sweden
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Jonsson PA, Graffmo KS, Andersen PM, Brännström T, Lindberg M, Oliveberg M, Marklund SL. Disulphide-reduced superoxide dismutase-1 in CNS of transgenic amyotrophic lateral sclerosis models. Brain 2005; 129:451-64. [PMID: 16330499 DOI: 10.1093/brain/awh704] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease afflicting the voluntary motor system. More than 100 different mutations in the ubiquitously expressed enzyme superoxide dismutase-1 (SOD1) have been associated with the disease. To search for the nature of the cytotoxicity of mutant SOD1s, amounts, enzymic activities and structural properties of the protein as well as the CNS histopathology were examined in multiple transgenic murine models. In order to generate the ALS phenotype within the short lifespan of the mouse, more than 20-fold increased rates of synthesis of mutant SOD1s appear to be required. The organs of transgenic mice expressing human wild-type SOD1 or either of the G93A and D90A mutant proteins showed high steady-state protein levels. The major proportion of these SOD1s in the CNS were inactive due to insufficient Cu charging and all contained subfractions with a reduced C57-C146 intrasubunit disulphide bond. Both G85R and the truncated G127insTGGG mutant showed low steady-state protein levels, lacked enzyme activity and had no C57-C146 disulphide bond. These mutants were also enriched in the CNS relative to other organs, suggesting inefficient recognition and degradation of misfolded disulphide-reduced SOD1 in susceptible tissues. In end-stage disease, despite 35-fold differences in levels of mutant SOD1s, similar amounts of detergent-resistant aggregates accumulated in the spinal cord. Small granular as well as larger more diffuse human SOD1 (hSOD1)-inclusions developed in all strains, the latter more pronounced in those with high hSOD1 levels. Widespread vacuolizations were seen in the strains with high levels of hSOD1 but not those with low, suggesting these alterations to be artefacts related to high hSOD1 levels and not to the ALS-causing cytotoxicity. The findings suggest that the motoneuron degeneration could be due to long-term exposure to misfolded aggregation-prone disulphide-reduced SOD1, which constitutes minute subfractions of the stable mutants and larger proportions of the unstable mutants.
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