1
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Sharma S, Deep S. Inhibition of fibril formation by polyphenols: molecular mechanisms, challenges, and prospective solutions. Chem Commun (Camb) 2024; 60:6717-6727. [PMID: 38835221 DOI: 10.1039/d4cc00822g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Fibril formation is a key feature in neurodegenerative diseases like Alzheimer's, Parkinson's, and systemic amyloidosis. Polyphenols, found in plant-based foods, show promise in inhibiting fibril formation and disrupting disease progression. The ability of polyphenols to break the amyloid fibrils of many disease-linked proteins has been tested in numerous studies. Polyphenols have their distinctive mechanism of action. They behave differently on various events in the aggregation pathway. Their action also differs for different proteins. Some polyphenols only inhibit the formation of fibrils whereas others break the preformed fibrils. Some break the fibrils into smaller species, and some change them to other morphologies. This article delves into the intricate molecular mechanisms underlying the inhibitory effects of polyphenols on fibrillogenesis, shedding light on their interactions with amyloidogenic proteins and the disruption of fibril assembly pathways. However, addressing the challenges associated with solubility, stability, and bioavailability of polyphenols is crucial. The current strategies involve nanotechnology to improve the solubility and bioavailability, thus showing the potential to enhance the efficacy of polyphenols as therapeutics. Advancements in structural biology, computational modeling, and biophysics have provided insights into polyphenol-fibril interactions, offering hope for novel therapies for neurodegenerative diseases and amyloidosis.
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Affiliation(s)
- Shilpa Sharma
- Department of Chemistry and Biochemistry, University of Wisconsin, Milwaukee, Wisconsin, USA
| | - Shashank Deep
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India.
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2
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Serebryany E, Martin RW, Takahashi GR. The Functional Significance of High Cysteine Content in Eye Lens γ-Crystallins. Biomolecules 2024; 14:594. [PMID: 38786000 PMCID: PMC11118217 DOI: 10.3390/biom14050594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
Cataract disease is strongly associated with progressively accumulating oxidative damage to the extremely long-lived crystallin proteins of the lens. Cysteine oxidation affects crystallin folding, interactions, and light-scattering aggregation especially strongly due to the formation of disulfide bridges. Minimizing crystallin aggregation is crucial for lifelong lens transparency, so one might expect the ubiquitous lens crystallin superfamilies (α and βγ) to contain little cysteine. Yet, the Cys content of γ-crystallins is well above the average for human proteins. We review literature relevant to this longstanding puzzle and take advantage of expanding genomic databases and improved machine learning tools for protein structure prediction to investigate it further. We observe remarkably low Cys conservation in the βγ-crystallin superfamily; however, in γ-crystallin, the spatial positioning of Cys residues is clearly fine-tuned by evolution. We propose that the requirements of long-term lens transparency and high lens optical power impose competing evolutionary pressures on lens βγ-crystallins, leading to distinct adaptations: high Cys content in γ-crystallins but low in βB-crystallins. Aquatic species need more powerful lenses than terrestrial ones, which explains the high methionine content of many fish γ- (and even β-) crystallins. Finally, we discuss synergies between sulfur-containing and aromatic residues in crystallins and suggest future experimental directions.
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Affiliation(s)
- Eugene Serebryany
- Department of Physiology & Biophysics, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
- Laufer Center for Physical & Quantitative Biology, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
| | - Rachel W. Martin
- Department of Chemistry, UCI Irvine, Irvine, CA 92697-2025, USA
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
| | - Gemma R. Takahashi
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
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3
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Hill JA, Nyathi Y, Horrell S, von Stetten D, Axford D, Owen RL, Beddard GS, Pearson AR, Ginn HM, Yorke BA. An ultraviolet-driven rescue pathway for oxidative stress to eye lens protein human gamma-D crystallin. Commun Chem 2024; 7:81. [PMID: 38600176 PMCID: PMC11006947 DOI: 10.1038/s42004-024-01163-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/27/2024] [Indexed: 04/12/2024] Open
Abstract
Human gamma-D crystallin (HGD) is a major constituent of the eye lens. Aggregation of HGD contributes to cataract formation, the leading cause of blindness worldwide. It is unique in its longevity, maintaining its folded and soluble state for 50-60 years. One outstanding question is the structural basis of this longevity despite oxidative aging and environmental stressors including ultraviolet radiation (UV). Here we present crystallographic structures evidencing a UV-induced crystallin redox switch mechanism. The room-temperature serial synchrotron crystallographic (SSX) structure of freshly prepared crystallin mutant (R36S) shows no post-translational modifications. After aging for nine months in the absence of light, a thiol-adduct (dithiothreitol) modifying surface cysteines is observed by low-dose SSX. This is shown to be UV-labile in an acutely light-exposed structure. This suggests a mechanism by which a major source of crystallin damage, UV, may also act as a rescuing factor in a finely balanced redox system.
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Affiliation(s)
- Jake A Hill
- School of Chemistry and Biosciences, University of Bradford, Richmond Road, Bradford, BD7 1DP, United Kingdom
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Yvonne Nyathi
- Faculty of Biological Sciences, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Sam Horrell
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - David von Stetten
- European Molecular Biology Laboratory, Notkestraße 85, 22607, Hamburg, Germany
| | - Danny Axford
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Robin L Owen
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Godfrey S Beddard
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Arwen R Pearson
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany
| | - Helen M Ginn
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany.
- Center for Free-Electron Laser Science, CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
| | - Briony A Yorke
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom.
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4
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Tovar-Ramírez ME, Schuth N, Rodríguez O, Kroll T, Saab-Rincon G, Costas M, Lampi K, Quintanar L. ATCUN-like Copper Site in βB2-Crystallin Plays a Protective Role in Cataract-Associated Aggregation. Inorg Chem 2023; 62:10592-10604. [PMID: 37379524 PMCID: PMC11156493 DOI: 10.1021/acs.inorgchem.3c00794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Cataract is the leading cause of blindness worldwide, and it is caused by crystallin damage and aggregation. Senile cataractous lenses have relatively high levels of metals, while some metal ions can directly induce the aggregation of human γ-crystallins. Here, we evaluated the impact of divalent metal ions in the aggregation of human βB2-crystallin, one of the most abundant crystallins in the lens. Turbidity assays showed that Pb2+, Hg2+, Cu2+, and Zn2+ ions induce the aggregation of βB2-crystallin. Metal-induced aggregation is partially reverted by a chelating agent, indicating the formation of metal-bridged species. Our study focused on the mechanism of copper-induced aggregation of βB2-crystallin, finding that it involves metal-bridging, disulfide-bridging, and loss of protein stability. Circular dichroism and electron paramagnetic resonance (EPR) revealed the presence of at least three Cu2+ binding sites in βB2-crystallin, one of them with spectroscopic features typical for Cu2+ bound to an amino-terminal copper and nickel (ATCUN) binding motif, which is found in Cu transport proteins. The ATCUN-like Cu binding site is located at the unstructured N-terminus of βB2-crystallin, and it could be modeled by a peptide with the first six residues in the protein sequence (NH2-ASDHQF-). Isothermal titration calorimetry indicates a nanomolar Cu2+ binding affinity for the ATCUN-like site. An N-truncated form of βB2-crystallin is more susceptible to Cu-induced aggregation and is less thermally stable, indicating a protective role for the ATCUN-like site. EPR and X-ray absorption spectroscopy studies reveal the presence of a copper redox active site in βB2-crystallin that is associated with metal-induced aggregation and formation of disulfide-bridged oligomers. Our study demonstrates metal-induced aggregation of βB2-crystallin and the presence of putative copper binding sites in the protein. Whether the copper-transport ATCUN-like site in βB2-crystallin plays a functional/protective role or constitutes a vestige from its evolution as a lens structural protein remains to be elucidated.
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Affiliation(s)
- Martin E. Tovar-Ramírez
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, 07360, Mexico
| | - Nils Schuth
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, 07360, Mexico
| | - Oscar Rodríguez
- Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City, 04510, Mexico
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, 94025, CA, USA
| | - Gloria Saab-Rincon
- Department of Biocatalysis and Cellular Engineering, Instituto de Biotecnología, Universidad Nacional Autónoma de Mexico, Cuernavaca, Morelos, 62210, Mexico
| | - Miguel Costas
- Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City, 04510, Mexico
| | - Kirsten Lampi
- Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, 97239, United States
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, 07360, Mexico
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Rodríguez-Meza O, Palomino-Vizcaino G, Quintanar L, Costas M. Mercury ions impact the kinetic and thermal stabilities of human lens γ-crystallins via direct metal-protein interactions. J Inorg Biochem 2023; 242:112159. [PMID: 36827733 DOI: 10.1016/j.jinorgbio.2023.112159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 02/06/2023] [Accepted: 02/06/2023] [Indexed: 02/17/2023]
Abstract
Loss of metal homeostasis may be involved in several age-related diseases, such as cataracts. Cataracts are caused by the aggregation of lens proteins into light-scattering high molecular weight complexes that impair vision. Environmental exposure to heavy metals, such as mercury, is a risk factor for cataract development. Indeed, mercury ions induce the non-amyloid aggregation of human γC- and γS crystallins, while human γD-crystallin is not sensitive to this metal. Using Differential Scanning Calorimetry (DSC), we evaluate the impact of mercury ions on the kinetic stability of the three most abundant human γ-crystallins. The metal/crystallin interactions were characterized using Isothermal Titration Calorimetry (ITC). Human γD-crystallins exhibited kinetic stabilization due to the presence of mercury ions, despite its thermal stability being decreased. In contrast, human γC- and γS-crystallins are both, thermally and kinetically destabilized by this metal, consistent with their sensitivity to mercury-induced aggregation. The interaction of human γ-crystallins with mercury ions is highly exothermic and complex, since the protein interacts with the metal at more than three sites. The isolated domains of human γ-D and its variant with the H22Q mutation were also studied, revealing the importance of these regions in the mercury-induced stabilization by a direct metal-protein interaction.
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Affiliation(s)
- Oscar Rodríguez-Meza
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, CdMx 04510, Mexico
| | | | - Liliana Quintanar
- Departamento de Química, Centro de Investigación y Estudios Avanzados (Cinvestav), CdMx 07360, Mexico
| | - Miguel Costas
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, CdMx 04510, Mexico.
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6
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Palomino-Vizcaino G, Schuth N, Domínguez-Calva JA, Rodríguez-Meza O, Martínez-Jurado E, Serebryany E, King JA, Kroll T, Costas M, Quintanar L. Copper Reductase Activity and Free Radical Chemistry by Cataract-Associated Human Lens γ-Crystallins. J Am Chem Soc 2023; 145:6781-6797. [PMID: 36918380 DOI: 10.1021/jacs.2c13397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Cataracts are caused by high-molecular-weight aggregates of human eye lens proteins that scatter light, causing lens opacity. Metal ions have emerged as important potential players in the etiology of cataract disease, as human lens γ-crystallins are susceptible to metal-induced aggregation. Here, the interaction of Cu2+ ions with γD-, γC-, and γS-crystallins, the three most abundant γ-crystallins in the lens, has been evaluated. Cu2+ ions induced non-amyloid aggregation in all three proteins. Solution turbidimetry, sodium dodecyl sulfate poly(acrylamide) gel electrophoresis (SDS-PAGE), circular dichroism, and differential scanning calorimetry showed that the mechanism for Cu-induced aggregation involves: (i) loss of β-sheet structure in the N-terminal domain; (ii) decreased thermal and kinetic stability; (iii) formation of metal-bridged species; and (iv) formation of disulfide-bridged dimers. Isothermal titration calorimetry (ITC) revealed distinct Cu2+ binding affinities in the γ-crystallins. Electron paramagnetic resonance (EPR) revealed two distinct Cu2+ binding sites in each protein. Spin quantitation demonstrated the reduction of γ-crystallin-bound Cu2+ ions to Cu+ under aerobic conditions, while X-ray absorption spectroscopy (XAS) confirmed the presence of linear or trigonal Cu+ binding sites in γ-crystallins. Our EPR and XAS studies revealed that γ-crystallins' Cu2+ reductase activity yields a protein-based free radical that is likely a Tyr-based species in human γD-crystallin. This unique free radical chemistry carried out by distinct redox-active Cu sites in human lens γ-crystallins likely contributes to the mechanism of copper-induced aggregation. In the context of an aging human lens, γ-crystallins could act not only as structural proteins but also as key players for metal and redox homeostasis.
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Affiliation(s)
- Giovanni Palomino-Vizcaino
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Nils Schuth
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - José A Domínguez-Calva
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Oscar Rodríguez-Meza
- Laboratorio de Biofisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico
| | - Eduardo Martínez-Jurado
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Eugene Serebryany
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Miguel Costas
- Laboratorio de Biofisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
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7
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Ozgul M, Nesburn AB, Nasralla N, Katz B, Taylan E, Kuppermann BD, Kenney MC. Stability Determination of Intact Humanin-G with Characterizations of Oxidation and Dimerization Patterns. Biomolecules 2023; 13:biom13030515. [PMID: 36979450 PMCID: PMC10046509 DOI: 10.3390/biom13030515] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/23/2023] [Accepted: 02/25/2023] [Indexed: 03/14/2023] Open
Abstract
Humanin is the first identified mitochondrial-derived peptide. Humanin-G (HNG) is a variant of Humanin that has significantly higher cytoprotective properties. Here, we describe the stability features of HNG in different conditions and characterize HNG degradation, oxidation, and dimerization patterns over short-term and long-term periods. HNG solutions were prepared in high-performance liquid chromatography (HPLC) water or MO formulation and stored at either 4 °C or 37 °C. Stored HNG samples were analyzed using HPLC and high-resolution mass spectrometry (HRMS). Using HPLC, full-length HNG peptides in HPLC water decreased significantly with time and higher temperature, while HNG in MO formulation remained stable up to 95% at 4 °C on day 28. HNG peptides in HPLC water, phosphate-buffered saline (PBS) and MO formulation were incubated at 37 °C and analyzed at day 1, day 7 and day 14 using HRMS. Concentrations of full-length HNG peptide in HPLC water and PBS declined over time with a corresponding appearance of new peaks that increased over time. These new peaks were identified to be singly oxidized HNG, doubly oxidized HNG, homodimerized HNG, singly oxidized homodimerized HNG, and doubly oxidized homodimerized HNG. Our results may help researchers improve the experimental design to further understand the critical role of HNG in human diseases.
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Affiliation(s)
- Mustafa Ozgul
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92617, USA
- Correspondence: (M.O.); (M.C.K.)
| | - Anthony B. Nesburn
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92617, USA
- Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | | | - Benjamin Katz
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Enes Taylan
- Department of Obstetrics and Gynecology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Baruch D. Kuppermann
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92617, USA
| | - Maria Cristina Kenney
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA 92617, USA
- Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA 92617, USA
- Correspondence: (M.O.); (M.C.K.)
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8
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Hou W, Pande A, Pande J. Oxidation of active cysteines mediates protein aggregation of S10R, the cataract-associated mutant of mouse GammaB-crystallin. Proteins 2022; 90:1987-2000. [PMID: 35726360 PMCID: PMC9561057 DOI: 10.1002/prot.26391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/15/2022] [Accepted: 06/01/2022] [Indexed: 11/09/2022]
Abstract
The Ser10 to Arg mutation in mouse γB-crystallin (MGB) has been associated with protein aggregation, dense nuclear opacity, and the degeneration of fiber cells in the lens core. Overexpression of the gap junction protein, connexin 46 (Cx46), was found to suppress the nuclear opacity and restore normal cell-cell contact. However, the molecular basis for the protein aggregation and related downstream effects were not evident from these studies. Here, we provide a comparison of the structures and solution properties of wild type MGB and the S10R mutant in vitro and show that, even though the mutation does not directly involve cysteine residues, some cysteines in the mutant protein are activated, leading to the enhanced formation of intermolecular disulfide-crosslinked protein aggregates relative to the wild-type. This occurs even as the protein structure is essentially unaltered. Thus, the primary event is enhanced protein aggregation due to the disulfide crosslinking of the mutant protein. We suggest that these aggregates eventually get deposited on fiber cell membranes. Since the gap junction protein, Cx46 is involved in the transport of reduced glutathione, we posit that these deposits interfere in Cx46-mediated glutathione transport and facilitate the oxidative stress-mediated downstream changes. Overexpression of Cx46 suppresses such oxidative aggregation. These studies provide a plausible explanation for the protein aggregation and other changes that accompany this mutation. If indeed cysteine oxidation is the primary event for protein aggregation also in vivo, then the S10R mutant mouse, which is currently available, could serve as a viable animal model for human age-onset cataract.
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Affiliation(s)
- Wenjuan Hou
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
- Current address: BioLegend Inc., 8999 BioLegend Way, San
Diego, CA 92121, United States
| | - Ajay Pande
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
| | - Jayanti Pande
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
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9
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Islam S, Do M, Frank BS, Hom GL, Wheeler S, Fujioka H, Wang B, Minocha G, Sell DR, Fan X, Lampi KJ, Monnier VM. α-Crystallin chaperone mimetic drugs inhibit lens γ-crystallin aggregation: potential role for cataract prevention. J Biol Chem 2022; 298:102417. [PMID: 36037967 PMCID: PMC9525908 DOI: 10.1016/j.jbc.2022.102417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/29/2022] Open
Abstract
Γ-Crystallins play a major role in age-related lens transparency. Their destabilization by mutations and physical chemical insults are associated with cataract formation. Therefore, drugs that increase their stability should have anticataract properties. To this end, we screened 2560 Federal Drug Agency–approved drugs and natural compounds for their ability to suppress or worsen H2O2 and/or heat-mediated aggregation of bovine γ-crystallins. The top two drugs, closantel (C), an antihelminthic drug, and gambogic acid (G), a xanthonoid, attenuated thermal-induced protein unfolding and aggregation as shown by turbidimetry fluorescence spectroscopy dynamic light scattering and electron microscopy of human or mouse recombinant crystallins. Furthermore, binding studies using fluorescence inhibition and hydrophobic pocket–binding molecule bis-8-anilino-1-naphthalene sulfonic acid revealed static binding of C and G to hydrophobic sites with medium-to-low affinity. Molecular docking to HγD and other γ-crystallins revealed two binding sites, one in the “NC pocket” (residues 50–150) of HγD and one spanning the “NC tail” (residues 56–61 to 168–174 in the C-terminal domain). Multiple binding sites overlap with those of the protective mini αA-crystallin chaperone MAC peptide. Mechanistic studies using bis-8-anilino-1-naphthalene sulfonic acid as a proxy drug showed that it bound to MAC sites, improved Tm of both H2O2 oxidized and native human gamma D, and suppressed turbidity of oxidized HγD, most likely by trapping exposed hydrophobic sites. The extent to which these drugs act as α-crystallin mimetics and reduce cataract progression remains to be demonstrated. This study provides initial insights into binding properties of C and G to γ-crystallins.
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Affiliation(s)
- Sidra Islam
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Michael Do
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Brett S Frank
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Grant L Hom
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Samuel Wheeler
- Dept of Integrative Biosciences, Oregon Health & Sciences University, Portland, OR 97239
| | - Hisashi Fujioka
- Cryo-EM Core Facility, School of Medicine, Case Western Reserve University, Case Western Reserve University, Cleveland, OH 44016
| | - Benlian Wang
- Center for Proteomics and Bioinformatics, Dept of Nutrition, Case Western Reserve University, Cleveland, OH 44106
| | - Geeta Minocha
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - David R Sell
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Xingjun Fan
- Dept of Cell Biology and Anatomy, Augusta University, Georgia, GA 30912
| | - Kirsten J Lampi
- Dept of Integrative Biosciences, Oregon Health & Sciences University, Portland, OR 97239
| | - Vincent M Monnier
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106; Dept of Biochemistry, Case Western Reserve University, Cleveland OH 44106.
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10
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Serebryany E, Chowdhury S, Woods CN, Thorn DC, Watson NE, McClelland AA, Klevit RE, Shakhnovich EI. A native chemical chaperone in the human eye lens. eLife 2022; 11:76923. [PMID: 35723573 PMCID: PMC9246369 DOI: 10.7554/elife.76923] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/13/2022] [Indexed: 12/02/2022] Open
Abstract
Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol’s molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol’s primary target was not the native, unfolded, or final aggregated states of the protein; rather, we propose that it was the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.
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Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Sourav Chowdhury
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Christopher N Woods
- Department of Biochemistry, University of Washington, Seattle, United States
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Nicki E Watson
- Center for Nanoscale Systems, Harvard University, Cambridge, United States
| | | | - Rachel E Klevit
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
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11
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Zinc and Copper Ions Induce Aggregation of Human β-Crystallins. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092970. [PMID: 35566320 PMCID: PMC9105653 DOI: 10.3390/molecules27092970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/28/2022] [Accepted: 05/01/2022] [Indexed: 11/16/2022]
Abstract
Cataracts are defined as the clouding of the lens due to the formation of insoluble protein aggregates. Metal ions exposure has been recognized as a risk factor in the cataract formation process. The γ and β crystallins are members of a larger family and share several structural features. Several studies have shown that copper and zinc ions induce the formation of γ-crystallins aggregates. However, the interaction of metal ions with β-crystallins, some of the most abundant crystallins in the lens, has not been explored until now. Here, we evaluate the effect of Cu(II) and Zn(II) ions on the aggregation of HβA1, as a representative of the acidic form, and HβB2, as a representative of the basic β-crystallins. We used several biophysical techniques and computational methods to show that Cu(II) and Zn(II) induce aggregation following different pathways. Both metal ions destabilize the proteins and impact protein folding. Copper induced a small conformational change in HβA1, leading to high-molecular-weight light-scattering aggregates, while zinc is more aggressive towards HβB2 and induces a larger conformational change. Our work provides information on the mechanisms of metal-induced aggregation of β-crystallins.
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12
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Serebryany E, Thorn DC, Quintanar L. Redox chemistry of lens crystallins: A system of cysteines. Exp Eye Res 2021; 211:108707. [PMID: 34332989 PMCID: PMC8511183 DOI: 10.1016/j.exer.2021.108707] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/09/2021] [Accepted: 07/23/2021] [Indexed: 11/28/2022]
Abstract
The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the β- and α-crystallins where pertinent.
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Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, Mexico
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13
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Bede-Ojimadu O, Orish CN, Bocca B, Ruggieri F, Frazzoli C, Orisakwe OE. Trace elements exposure and risk in age-related eye diseases: a systematic review of epidemiological evidence. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, TOXICOLOGY AND CARCINOGENESIS 2021; 39:293-339. [PMID: 34114934 DOI: 10.1080/26896583.2021.1916331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This systematic review aimed to evaluate existing evidence on the associations between trace elements exposure and age-related eye diseases. PubMed and Google scholar databases were searched for epidemiological and postmortem studies on the relationship between exposure to trace elements and Age-related eye diseases such as age-related macular degeneration (AMD), cataract, glaucoma and diabetic retinopathy (DR), in population groups aged 40 years and above. Available evidence suggests that cadmium (Cd) exposure may be positively associated with the risks of AMD and cataract. There is also evidence that exposure to lead (Pb) may be positively associated with higher risk of cataract and glaucoma. There is limited number of relevant studies and lack of prospective studies for most of the investigated associations. Evidence for other trace elements is weak and inconsistent, and the number of available studies is small. Likewise, there are very few relevant studies on the role of trace elements in DR. Chemical elements that affect the distribution and absorption of other trace elements have never been investigated. The suggestive but limited evidence motivates large and quality prospective studies to fully characterize the impact of exposure to trace (toxic and essential) elements on age-related eye diseases.
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Affiliation(s)
- Onyinyechi Bede-Ojimadu
- Department of Chemical Pathology, Faculty of Medicine, Nnamdi Azikiwe University, Nnewi, Nigeria
| | - Chinna N Orish
- Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences University of Port Harcourt, Port Harcourt, Choba, Nigeria
| | - Beatrice Bocca
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy
| | - Flavia Ruggieri
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy
| | - Chiara Frazzoli
- Department of Cardiovascular and Endocrine-Metabolic Diseases, and Ageing, Istituto Superiore di Sanità, Rome, Italy
| | - Orish E Orisakwe
- African Centre of Excellence for Public Health and Toxicological Research (ACE-PUTOR), University of Port Harcourt, Port Harcourt, Rivers, Nigeria
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14
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Rocha MA, Sprague-Piercy MA, Kwok AO, Roskamp KW, Martin RW. Chemical Properties Determine Solubility and Stability in βγ-Crystallins of the Eye Lens. Chembiochem 2021; 22:1329-1346. [PMID: 33569867 PMCID: PMC8052307 DOI: 10.1002/cbic.202000739] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Indexed: 11/10/2022]
Abstract
βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.
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Affiliation(s)
- Megan A. Rocha
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Marc A. Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| | - Ashley O. Kwok
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
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15
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Nagashima H, Sasaki N, Amano S, Nakamura S, Hayano M, Tsubota K. Oral administration of resveratrol or lactic acid bacterium improves lens elasticity. Sci Rep 2021; 11:2174. [PMID: 33500490 PMCID: PMC7838312 DOI: 10.1038/s41598-021-81748-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/08/2021] [Indexed: 02/03/2023] Open
Abstract
A decrease in the elasticity of the ocular lens during aging is associated with loss of the accommodative ability of the eye, leading to presbyopia. Although near vision impairment is a social issue affecting the length of healthy life expectancy and productivity of elderly people, an effective treatment to improve near vision has not yet become available. Here we examined the effect of Enterococcus faecium WB2000, Lactobacillus pentosus TJ515, and resveratrol on lens elasticity in rats, where the stiffness of the ocular lens increases exponentially during the aging process. A combination of WB2000 and resveratrol improved lens elasticity not only in the long term but also with just short-term treatment. In addition, TJ515 decreased stiffness in the eye lens with long-term treatment. Therefore, the oral administration of WB2000 and resveratrol or TJ515 may be a potential approach for managing the progression of near vision impairment.
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Affiliation(s)
- Hayato Nagashima
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
- Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Nobunari Sasaki
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
- Tsubota Laboratory, Inc., Tokyo, Japan
| | - Sachie Amano
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Shigeru Nakamura
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Motoshi Hayano
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
- Tsubota Laboratory, Inc., Tokyo, Japan
| | - Kazuo Tsubota
- Department of Ophthalmology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
- Tsubota Laboratory, Inc., Tokyo, Japan.
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16
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Furkan M, Khan RH. Process, Outcomes and Possible Elimination of Aggregation with Special Reference to Heme Proteins; Likely Remediations of Proteinopathies. Curr Protein Pept Sci 2021; 21:573-583. [PMID: 32013844 DOI: 10.2174/1389203721666200204122732] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 01/08/2020] [Accepted: 01/10/2020] [Indexed: 01/13/2023]
Abstract
Protein folding is a natural phenomenon through which a linear polypeptide possessing necessary information attains three-dimension functionally active conformation. This is a complex and multistep process and therefore, the presence of several intermediary structures could be speculated as a result of protein folding. In in vivo, this folding process is governed by the assistance of other proteins called molecular chaperones and heat shock proteins. Due to the mechanism of protein folding, these intermediary structures remain major challenge for modern biology. Mutation in gene encoding amino acid can cause adverse environmental conditions which may result in misfolding of the linear polypeptide followed by the formation of aggregates and amyloidosis. Aggregation contributes to the pathophysiology of several maladies including diabetes mellitus, Huntington's and Alzheimer's disease. The propensity of native structure to form aggregated and fibrillar assemblies is a hallmark of amyloidosis. During aggregation of a protein, transition from α helix to β sheet is observed, and mainly β sheeted structure is visualised in a mature fibril. Heme proteins are very crucial for major life activities like transport of oxygen and carbon dioxide, synthesis of ATP, role in electron transport chain, and detoxification of free radicals formed during biochemical reactions. Any structural variation in the heme proteins may lead to a fatal response. Hence characterization of the folding intermediates becomes crucial. The characterization has been deciphered with the help of strong denaturants like acetonitrile and TFE. Moreover, possible role of elimination of these aggregates and prevention of protein denaturation is also discussed. Current review deals with the basic process and mechanism of the protein folding in general and the ultimate outcomes of the protein misfolding. Since Native conformation of heme proteins is essential for some vital activities as listed above, we have discussed possible prevention of denaturation and aggregation of heme proteins such as Hb, cyt c, catalase & peroxidase.
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Affiliation(s)
- Mohammad Furkan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University Aligarh, UP, 202002, India
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University Aligarh, UP, 202002, India
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17
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An amyloidogenic hexapeptide from the cataract-associated γD-crystallin is a model for the full-length protein and is inhibited by naphthoquinone-tryptophan hybrids. Int J Biol Macromol 2020; 157:424-433. [DOI: 10.1016/j.ijbiomac.2020.04.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/11/2020] [Accepted: 04/11/2020] [Indexed: 12/17/2022]
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18
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Roskamp KW, Azim S, Kassier G, Norton-Baker B, Sprague-Piercy MA, Miller RJD, Martin RW. Human γS-Crystallin-Copper Binding Helps Buffer against Aggregation Caused by Oxidative Damage. Biochemistry 2020; 59:2371-2385. [PMID: 32510933 DOI: 10.1021/acs.biochem.0c00293] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Divalent metal cations can play a role in protein aggregation diseases, including cataract. Here we compare the aggregation of human γS-crystallin, a key structural protein of the eye lens, via mutagenesis, ultraviolet light damage, and the addition of metal ions. All three aggregation pathways result in globular, amorphous-looking structures that do not elongate into fibers. We also investigate the molecular mechanism underlying copper(II)-induced aggregation. This work was motivated by the observation that zinc(II)-induced aggregation of γS-crystallin is driven by intermolecular bridging of solvent-accessible cysteine residues, while in contrast, copper(II)-induced aggregation of this protein is exacerbated by the removal of solvent-accessible cysteines via mutation. Here we find that copper(II)-induced aggregation results from a complex mechanism involving multiple interactions with the protein. The initial protein-metal interactions result in the reduction of Cu(II) to Cu(I) with concomitant oxidation of γS-crystallin. In addition to the intermolecular disulfides that represent a starting point for aggregation, intramolecular disulfides also occur in the cysteine loop, a region of the N-terminal domain that was previously found to mediate the early stages of cataract formation. This previously unobserved ability of γS-crystallin to transfer disulfides intramolecularly suggests that it may serve as an oxidation sink for the lens after glutathione levels have become depleted during aging. γS-Crystallin thus serves as the last line of defense against oxidation in the eye lens, a result that underscores the chemical functionality of this protein, which is generally considered to play a purely structural role.
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Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Sana Azim
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Günther Kassier
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Brenna Norton-Baker
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States.,Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Marc A Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - R J Dwyane Miller
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany.,Departments of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Rachel W Martin
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
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19
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Fernández-Silva A, French-Pacheco L, Rivillas-Acevedo L, Amero C. Aggregation pathways of human γ D crystallin induced by metal ions revealed by time dependent methods. PeerJ 2020; 8:e9178. [PMID: 32566392 PMCID: PMC7295030 DOI: 10.7717/peerj.9178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/22/2020] [Indexed: 12/17/2022] Open
Abstract
Cataract formation is a slow accumulative process due to protein aggregates promoted by different factors over time. Zinc and copper ions have been reported to induce the formation of aggregates opaque to light in the human gamma D crystallin (HγD) in a concentration and temperature dependent manner. In order to gain insight into the mechanism of metal-induced aggregation of HγD under conditions that mimic more closely the slow, accumulative process of the disease, we have studied the non-equilibrium process with the minimal metal dose that triggers HγD aggregation. Using a wide variety of biophysics techniques such as turbidimetry, dynamic light scattering, fluorescence, nuclear magnetic resonance and computational methods, we obtained information on the molecular mechanisms for the formation of aggregates. Zn(II) ions bind to different regions at the protein, probably with similar affinities. This binding induces a small conformational rearrangement within and between domains and aggregates via the formation of metal bridges without any detectable unfolded intermediates. In contrast, Cu(II)-induced aggregation includes a lag time, in which the N-terminal domain partially unfolds while the C-terminal domain and parts of the N-terminal domain remain in a native-like conformation. This partially unfolded intermediate is prone to form the high-molecular weight aggregates. Our results clearly show that different external factors can promote protein aggregation following different pathways.
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Affiliation(s)
- Arline Fernández-Silva
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Leidys French-Pacheco
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico.,Centro de Investigación en Dinámica Celular, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Lina Rivillas-Acevedo
- Centro de Investigación en Dinámica Celular, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Carlos Amero
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
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20
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Roskamp KW, Kozlyuk N, Sengupta S, Bierma JC, Martin RW. Divalent Cations and the Divergence of βγ-Crystallin Function. Biochemistry 2019; 58:4505-4518. [PMID: 31647219 DOI: 10.1021/acs.biochem.9b00507] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The βγ-crystallin superfamily contains both β- and γ-crystallins of the vertebrate eye lens and the microbial calcium-binding proteins, all of which are characterized by a common double-Greek key domain structure. The vertebrate βγ-crystallins are long-lived structural proteins that refract light onto the retina. In contrast, the microbial βγ-crystallins bind calcium ions. The βγ-crystallin from the tunicate Ciona intestinalis (Ci-βγ) provides a potential link between these two functions. It binds calcium with high affinity and is found in a light-sensitive sensory organ that is highly enriched in metal ions. Thus, Ci-βγ is valuable for investigating the evolution of the βγ-crystallin fold away from calcium binding and toward stability in the apo form as part of the vertebrate lens. Here, we investigate the effect of Ca2+ and other divalent cations on the stability and aggregation propensity of Ci-βγ and human γS-crystallin (HγS). Beyond Ca2+, Ci-βγ is capable of coordinating Mg2+, Sr2+, Co2+, Mn2+, Ni2+, and Zn2+, although only Sr2+ is bound with comparable affinity to its preferred metal ion. The extent to which the tested divalent cations stabilize Ci-βγ structure correlates strongly with ionic radius. In contrast, none of the tested divalent cations improved the stability of HγS, and some of them induced aggregation. Zn2+, Ni2+, and Co2+ induce aggregation by interacting with cysteine residues, whereas Cu2+-mediated aggregation proceeds via a different binding site.
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Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Natalia Kozlyuk
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Suvrajit Sengupta
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Jan C Bierma
- Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
| | - Rachel W Martin
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States.,Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
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21
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Abstract
In the vertebrate eye, limiting oxidation of proteins and lipids is key to maintaining lens function and avoiding cataract formation. A study by Serebryany et al. identifies a surprising contributor to the eye's oxidative defense in their demonstration that γD-crystallin (HγD) functions as an oxidoreductase and uses disulfide exchange to initiate aggregation of mutant crystallins that mimic oxidative damage. These insights suggest a mechanism by which a dynamic pool of closely packed proteins might avoid oxidation-driven protein-folding traps, providing new avenues to understand the basis of a human disease with global impact.
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Affiliation(s)
- Roy A Quinlan
- From the Department of Biosciences, University of Durham, Mountjoy Science Site, Durham DH13LE, United Kingdom.
| | - Philip J Hogg
- Centenary Institute, NHMRC Clinical Trials Center, Sydney Medical School, University of Sydney, NSW 2006, Australia.
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22
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Thorn DC, Grosas AB, Mabbitt PD, Ray NJ, Jackson CJ, Carver JA. The Structure and Stability of the Disulfide-Linked γS-Crystallin Dimer Provide Insight into Oxidation Products Associated with Lens Cataract Formation. J Mol Biol 2018; 431:483-497. [PMID: 30552875 DOI: 10.1016/j.jmb.2018.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/05/2018] [Indexed: 11/18/2022]
Abstract
The reducing environment in the eye lens diminishes with age, leading to significant oxidative stress. Oxidation of lens crystallin proteins is the major contributor to their destabilization and deleterious aggregation that scatters visible light, obscures vision, and ultimately leads to cataract. However, the molecular basis for oxidation-induced aggregation is unknown. Using X-ray crystallography and small-angle X-ray scattering, we describe the structure of a disulfide-linked dimer of human γS-crystallin that was obtained via oxidation of C24. The γS-crystallin dimer is stable at glutathione concentrations comparable to those in aged and cataractous lenses. Moreover, dimerization of γS-crystallin significantly increases the protein's propensity to form large insoluble aggregates owing to non-cooperative domain unfolding, as is observed in crystallin variants associated with early-onset cataract. These findings provide insight into how oxidative modification of crystallins contributes to cataract and imply that early-onset and age-related forms of the disease share comparable development pathways.
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Affiliation(s)
- David C Thorn
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Aidan B Grosas
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Peter D Mabbitt
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Nicholas J Ray
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Colin J Jackson
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia.
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23
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Serebryany E, Yu S, Trauger SA, Budnik B, Shakhnovich EI. Dynamic disulfide exchange in a crystallin protein in the human eye lens promotes cataract-associated aggregation. J Biol Chem 2018; 293:17997-18009. [PMID: 30242128 DOI: 10.1074/jbc.ra118.004551] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/14/2018] [Indexed: 12/31/2022] Open
Abstract
Increased light scattering in the eye lens due to aggregation of the long-lived lens proteins, crystallins, is the cause of cataract disease. Several mutations in the gene encoding human γD-crystallin (HγD) cause misfolding and aggregation. Cataract-associated substitutions at Trp42 cause the protein to aggregate in vitro from a partially unfolded intermediate locked by an internal disulfide bridge, and proteomic evidence suggests a similar aggregation precursor is involved in age-onset cataract. Surprisingly, WT HγD can promote aggregation of the W42Q variant while itself remaining soluble. Here, a search for a biochemical mechanism for this interaction has revealed a previously unknown oxidoreductase activity in HγD. Using in vitro oxidation, mutational analysis, cysteine labeling, and MS, we have assigned this activity to a redox-active internal disulfide bond that is dynamically exchanged among HγD molecules. The W42Q variant acts as a disulfide sink, reducing oxidized WT and forming a distinct internal disulfide that kinetically traps the aggregation-prone intermediate. Our findings suggest a redox "hot potato" competition among WT and mutant or modified polypeptides wherein variants with the lowest kinetic stability are trapped in aggregation-prone intermediate states upon accepting disulfides from more stable variants. Such reactions may occur in other long-lived proteins that function in oxidizing environments. In these cases, aggregation may be forestalled by inhibiting disulfide flow toward mutant or damaged polypeptides.
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Affiliation(s)
- Eugene Serebryany
- From the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Shuhuai Yu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122 Jiangsu, China
| | | | - Bogdan Budnik
- Mass Spectrometry and Proteomics Resource Laboratory, Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Eugene I Shakhnovich
- From the Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138.
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