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Chaki S, Santra S, Dasgupta S. Fibrillation of Human Serum Albumin Differentially Affected by Asp-, Arg-, and Tyr-Capped Gold Nanoparticles. J Phys Chem B 2024; 128:3538-3553. [PMID: 38507578 DOI: 10.1021/acs.jpcb.3c06932] [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: 03/22/2024]
Abstract
Fibrillation of proteins is associated with a number of debilitating diseases, including various neurodegenerative disorders. Prevention of the protein fibrillation process is therefore of immense importance. We investigated the effect of amino acid-capped AuNPs on the prevention of the fibrillation process of human serum albumin (HSA), a model protein. Amino acid-capped AuNPs of varying sizes and agglomeration extents were synthesized under physiological conditions. The AuNPs were characterized by their characteristic surface plasmon resonance (SPR), and their interactions with HSA were investigated through emission spectroscopy in addition to circular dichroism (CD) spectral analyses. Fluorescence lifetime imaging (FLIM) as well as transmission electron microscopy (TEM) were used to observe the fibrillar network. Thermodynamic and kinetic analyses from CD and fluorescence emission spectra provided insights into the fibrillation pathway adopted by HSA in the presence of capped AuNPs. Kinetics of the fibrillation pathway followed by ThT fluorescence emission confirmed the sigmoidal nature of the process. The highest cooperativity was observed in the case of Asp-AuNPs with HSA. This was in accordance with the ΔG value obtained from the CD spectral analyses, where Arg-AuNPs with HSA showed the highest positive ΔG value and Asp-AuNPs with HSA showed the most negative ΔG value. The study provides information about the potential use of conjugate AuNPs to monitor the fibrillation process in proteins.
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Affiliation(s)
- Sreshtha Chaki
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Sujan Santra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Swagata Dasgupta
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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2
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Lin N, Zhang Y, Song X, Xu J, Luo C, Tian Q, Yao K, Wu W, Chen X, Hu L. Cataract-causing mutations S78F and S78P of γD-crystallin decrease protein conformational stability and drive aggregation. Int J Biol Macromol 2023; 253:126910. [PMID: 37739288 DOI: 10.1016/j.ijbiomac.2023.126910] [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: 07/03/2023] [Revised: 08/28/2023] [Accepted: 09/13/2023] [Indexed: 09/24/2023]
Abstract
Congenital cataract is the leading cause of childhood blindness, which primarily results from genetic factors. γD-crystallin is the most abundant γ-crystallin and is essential for maintaining lens transparency and refractivity. Numerous mutations in γD-crystallin have been reported with unclear pathogenic mechanism. Two different cataract-causing mutations Ser78Phe and Ser78Pro in γD-crystallin were previously identified at the same conserved Ser78 residue. In this work, firstly, we purified the mutants and characterized for the structural change using fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and size-exclusion chromatography (SEC). Both mutants were prone to form insoluble precipitates when expressed in Escherichia coli strain BL21 (DE3) cells. Compared with wild-type (WT), both mutations caused structural disruption, increased hydrophobic exposure, decreased solubility, and reduced thermal stability. Next, we investigated the aggregation of the mutants at the cellular level. Overexpression the mutants in HLE-B3 and HEK 293T cells could induce aggresome formations. The environmental stresses (including heat, ultraviolet irradiation and oxidative stress) promoted the formation of aggregates. Moreover, the intracellular S78F and S78P aggregates could be reversed by lanosterol. Molecular dynamic simulation indicated that both mutations disrupted the structural integrity of Greek-key motif 2. Hence, our results reveal the vital role of conserved Ser78 in maintaining the structural stability, which can offer new insights into the mechanism of cataract formation.
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Affiliation(s)
- Ningqin Lin
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang Province, China; Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Ying Zhang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Xiaohui Song
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Chenqi Luo
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Qing Tian
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China.
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China.
| | - Lidan Hu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang Province, China.
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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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4
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Aggregation of Irisin and its Prevention by Trehalose: A Biophysical Approach. J Mol Struct 2023. [DOI: 10.1016/j.molstruc.2023.135078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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5
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Xu W, Xu J, Shi C, Wu J, Wang H, Wu W, Chen X, Hu L. A novel cataract-causing mutation Ile82Met of γA crystallin trends to aggregate with unfolding intermediate. Int J Biol Macromol 2022; 211:357-367. [PMID: 35513103 DOI: 10.1016/j.ijbiomac.2022.04.205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 02/06/2022] [Accepted: 04/27/2022] [Indexed: 11/05/2022]
Abstract
Cataract is the most common pathogenic ophthalmic disease leading to blindness in children worldwide. Genetic disorder is the leading cause of congenital cataract, among which crystallin mutations have a high incidence. There are few reports on γA-crystallin, one critical member of crystallin superfamilies. In this study, we identified a novel pathogenic mutation (Ile82Met) in γA-crystallin from a three-generation Chinese family with cataract, and investigated the potential molecular mechanism in detail. To elucidate the pathogenic mechanism of I82M mutant, spectroscopic and solubility experiments were performed to determine the difference between the purified γA-crystallin wild type (WT) and I82M mutant under both physiological conditions and environmental stresses (UV irradiation, thermal denaturation or chemical denaturation). The I82M mutant did not affect the secondary/tertiary structure of monomeric γA-crystallin under physiological status, but decreased protein stability and increased aggregatory potency under the stressful treatment. Surprisingly, the chemical denaturation caused I82M to switch from the two-state unfolding of γA-crystallin to three-state unfolding involving an unfolding intermediate. This study expands the genetic variation map of cataract, and provides novel insights into the pathomechanism, in particular, filling in a gap in the understanding of γA-crystallin mutants causing cataract.
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Affiliation(s)
- Wanyue Xu
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China; Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Caiping Shi
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Jing Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Huaxia Wang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China.
| | - Lidan Hu
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China.
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Khoshaman K, Ghahramani M, Shahsavani MB, Moosavi-Movahedi AA, Kurganov BI, Yousefi R. Myopathy-associated G154S mutation causes important changes in the conformational stability, amyloidogenic properties, and chaperone-like activity of human αB-crystallin. Biophys Chem 2021; 282:106744. [PMID: 34983005 DOI: 10.1016/j.bpc.2021.106744] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/02/2022]
Abstract
Glycine to serine substitution at position 154 of human αB-crystallin (αB-Cry) is behind the development of cardiomyopathy and late-onset distal myopathy. The current study was conducted with the aim to investigate the structural and functional features of the G154S mutant αB-Cry using various spectroscopic techniques and microscopic analyses. The secondary and tertiary structures of human αB-Cry were preserved mainly in the presence of G154S mutation, but the mutant protein indicated a reduced chaperone-like activity when γ-Cry as its natural partner in eye lenses was the substrate protein. Moreover, a significant reduction in the enzyme refolding ability and in vivo chaperone activity of the mutant protein were observed. Also, the mutant protein displayed reduced conformational stability upon urea-induced denaturation. Both fluorescence and electron microscopic analyses suggested that G154S mutant protein has an increased susceptibility for amyloid fibril formation. Therefore, the pathomechanism of G154S mutation can be explained by its attenuated chaperone function, decreased conformational stability, and increased amyloidogenic propensity. Some of these important changes may also alter the correct interaction of the mutated αB-Cry with its target proteins in myopathy.
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Affiliation(s)
- Kazem Khoshaman
- Protein Chemistry Laboratory (PCL), Department of Biology, Shiraz University, Shiraz, Iran
| | - Maryam Ghahramani
- Protein Chemistry Laboratory (PCL), Department of Biology, Shiraz University, Shiraz, Iran
| | | | | | - Boris I Kurganov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Reza Yousefi
- Protein Chemistry Laboratory (PCL), Department of Biology, Shiraz University, Shiraz, Iran; Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran.
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7
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Hsueh SS, Lu JH, Wu JW, Lin TH, Wang SSS. Protection of human γD-crystallin protein from ultraviolet C-induced aggregation by ortho-vanillin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 261:120023. [PMID: 34098480 DOI: 10.1016/j.saa.2021.120023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Cataract is known as one of the leading causes of vision impairment worldwide. While the detailed mechanism of cataratogenesis remains unclear, cataract is believed to be correlated with the aggregation and/or misfolding of human ocular lens proteins called crystallins. A 173-residue structural protein human γD-crystallin is a major γ-crystallin protein in the human eye lens and associated with the development of juvenile and mature-onset cataracts. This work is aimed at investigating the effect of a small molecule, e.g., ortho-vanillin, on human γD-crystallin aggregation upon exposure to ultraviolet-C irradiation. According to the findings of right-angle light scattering, transmission electron microscopy, and gel electrophoresis, ortho-vanillin was demonstrated to dose-dependently suppress ultraviolet-C-triggered aggregation of human γD-crystallin. Results from the synchronous fluorescence spectroscopy, tryptophan fluorescence quenching, and molecular docking studies revealed the structural change of γD-crystallin induced by the interaction/binding between ortho-vanillin and protein. We believe the outcome from this work may contribute to the development of potential therapeutics for cataract.
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Affiliation(s)
- Shu-Shun Hsueh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Jian-Hong Lu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Josephine W Wu
- Department of Optometry, Yuanpei University of Medical Technology, Hsinchu City 30015, Taiwan.
| | - Ta-Hsien Lin
- Basic Research Division, Medical Research Department, Taipei Veterans General Hospital, Taipei 11217, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan.
| | - Steven S-S Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
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8
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Xu J, Wang H, Wu C, Wang A, Wu W, Xu J, Luo C, Ni S, Yao K, Chen X. Pathogenic mechanism of congenital cataract caused by the CRYBA1/A3-G91del variant and related intervention strategies. Int J Biol Macromol 2021; 189:44-52. [PMID: 34419537 DOI: 10.1016/j.ijbiomac.2021.08.111] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 10/20/2022]
Abstract
Congenital cataracts, which are genetically heterogeneous eye disorders, lead to visual impairment in childhood. In our previous study, we identified a novel mutation in exon 4 of the CRYBA1/BA3 gene, which resulted in the deletion of a highly conserved glycine at codon 91 (G91del) and perinuclear zonular cataract. The G91del variant is one of the most frequent pathogenic mutations in CRYBA1/BA3; however, its pathogenic mechanism remains unclear. In this study, we purified βA3-crystallin and the βA3-G91del variant. βA3-G91del was prone to proteolysis and exhibited very low solubility and low structural stability. Next, we constructed a CRYBA1/BA3 mutant cell model and observed that G91del mutant proteins were more sensitive to environmental stress and prone to form aggregates. Size-exclusion chromatography and molecular dynamics simulation showed that the G91del mutation impaired the ability of βA3 to form homo-oligomers. In addition, the protein folding process of βA3-G91del was complicated and showed more intermediate states, resulting in amyloid fiber aggregation and induction of cellular apoptosis. Finally, we investigated intervention strategies for congenital cataract caused by the CRYBA1/A3-G91del variant. The addition of lanosterol reversed the negative effects of the G91del mutation under external stress. This study may help explore potential treatment strategies for related cataracts.
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Affiliation(s)
- Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Huaxia Wang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Chengpeng Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Ailing Wang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Jia Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Chenqi Luo
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Shuang Ni
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China.
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China.
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9
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Trehalose Restrains the Fibril Load towards α-Lactalbumin Aggregation and Halts Fibrillation in a Concentration-Dependent Manner. Biomolecules 2021; 11:biom11030414. [PMID: 33799517 PMCID: PMC8001226 DOI: 10.3390/biom11030414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 01/12/2023] Open
Abstract
Protein aggregation and misfolding are some of the most challenging obstacles, customarily studied for their association with amyloid pathologies. The mechanism of amyloid fibrillation development is a dynamic phenomenon involving various factors such as the intrinsic properties of protein and the physical and chemical environmental conditions. The purpose of this study was to see the thermal aggregation profile of alpha-lactalbumin (α-LA) and to delineate the effect of trehalose on its aggregation profile. α-LA was subjected to thermal aggregation at high concentrations. UV-Vis spectroscopy, a turbidity assay, intrinsic fluorescence, Rayleigh scattering and a thioflavin T (ThT) assay explained the steady outcomes that 1 M trehalose repressed α-LA aggregation in the most effective way followed by 0.75 M and 0.5 M and to a significantly lesser degree by 0.25 M. Multi spectroscopic obser Sania Bashir ations were further entrenched by microscopy. Transmission electron microscopy confirmed that in the presence of its higher concentration, trehalose hinders fibril development in α-LA. In vitro studies were further validated by in silico studies. Molecular docking analysis indicated that trehalose occupied the binding pocket cavity of α-LA and offered several significant interactions, including H-bonds with important residues. This study provides a platform for trehalose in the therapeutic management of protein aggregation-related diseases.
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Fu C, Xu J, Yang X, Chen X, Yao K. Cataract-causing mutations L45P and Y46D impair the thermal stability of γC-crystallin. Biochem Biophys Res Commun 2021; 539:70-76. [PMID: 33422942 DOI: 10.1016/j.bbrc.2020.12.096] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/28/2020] [Indexed: 10/22/2022]
Abstract
Crystallin gene mutations are responsible for about half of the congenital cataract caused by genetic disorders. L45P and Y46D mutations of γC-crystallin have been reported in patients with nuclear congenital cataract. In this study, we explored the thermal stability of wild type (WT), L45P, and Y46D mutants of γC-crystallin at low and high concentrations, as well as the effect of αA-crystallin on the thermal stability of mutants. Spectroscopic experiments were used to monitor the structural changes on temperature-gradient and time-course heating process. Intermediate morphologies were determined through cryo-electron microscopy. The thermal stability of WT and mutants at concentrations ranging up to hundreds of milligrams were assessed via the UNcle multifunctional protein stability analysis system. The results showed that L45P and Y46D mutations impaired the thermal stability of γC-crystallin at low (0.2 mg/mL) and high concentrations (up to 200 mg/mL). Notably, with increase in protein concentration, the thermal stability of L45P and Y46D mutants of γC-crystallin simultaneously decreased. Thermal stability of L45P and Y46D mutants could be rescued by αA-crystallin in a concentration-dependent manner. The dramatic decrease in thermal stability of γC-crystallin caused by L45P and Y46D mutations contributed to congenital cataract in the mature human lens.
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Affiliation(s)
- Chenxi Fu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China
| | - Xiaoxia Yang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou, 310020, China.
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China.
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11
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Cataract-causing mutations L45P and Y46D promote γC-crystallin aggregation by disturbing hydrogen bonds network in the second Greek key motif. Int J Biol Macromol 2020; 167:470-478. [PMID: 33278449 DOI: 10.1016/j.ijbiomac.2020.11.158] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/23/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Congenital cataracts caused by genetic disorders are the primary cause of child blindness across the globe. In this work, we investigated the underlying molecular mechanism of two mutations, L45P and Y46D of γC-crystallin in two Chinese families causing nuclear congenital cataracts. Spectroscopic experiments were performed to determine structural differences between the wild-type (WT) and the L45P or Y46D mutant of γC-crystallin, and the structural stabilities of the WT and mutant proteins were measured under environmental stress (ultraviolet irradiation, pH disorders, oxidative stress, or chemical denaturation). The L45P and Y46D mutants had lower protein solubility and more hydrophobic residues exposed, making them prone to aggregation under environmental stress. The dynamic molecular simulation revealed that the L45P and Y46D mutations destabilized γC-crystallin by altering the hydrogen bonds network around the Trp residues in the second Greek key motif. In summary, L45P and Y46D mutants of γC-crystallin caused more hydrophobic residues to be solvent-exposed, lowered the solubility of γC-crystallin, and increased aggregation propensity under environmental stress. These might be the pathogenesis of γC-crystallin L45P and Y46D mutants related to congenital cataract.
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12
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Shaw WJ, Tarasevich BJ, Buchko GW, Arachchige RMJ, Burton SD. Controls of nature: Secondary, tertiary, and quaternary structure of the enamel protein amelogenin in solution and on hydroxyapatite. J Struct Biol 2020; 212:107630. [PMID: 32979496 PMCID: PMC7744360 DOI: 10.1016/j.jsb.2020.107630] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/12/2020] [Accepted: 09/17/2020] [Indexed: 10/23/2022]
Abstract
Amelogenin, a protein critical to enamel formation, is presented as a model for understanding how the structure of biomineralization proteins orchestrate biomineral formation. Amelogenin is the predominant biomineralization protein in the early stages of enamel formation and contributes to the controlled formation of hydroxyapatite (HAP) enamel crystals. The resulting enamel mineral is one of the hardest tissues in the human body and one of the hardest biominerals in nature. Structural studies have been hindered by the lack of techniques to evaluate surface adsorbed proteins and by amelogenin's disposition to self-assemble. Recent advancements in solution and solid state nuclear magnetic resonance (NMR) spectroscopy, atomic force microscopy (AFM), and recombinant isotope labeling strategies are now enabling detailed structural studies. These recent studies, coupled with insights from techniques such as CD and IR spectroscopy and computational methodologies, are contributing to important advancements in our structural understanding of amelogenesis. In this review we focus on recent advances in solution and solid state NMR spectroscopy and in situ AFM that reveal new insights into the secondary, tertiary, and quaternary structure of amelogenin by itself and in contact with HAP. These studies have increased our understanding of the interface between amelogenin and HAP and how amelogenin controls enamel formation.
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Affiliation(s)
- Wendy J Shaw
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
| | - Barbara J Tarasevich
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Garry W Buchko
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA; School of Molecular Bioscience, Washington State University, Pullman, WA 99164, USA
| | - Rajith M J Arachchige
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Sarah D Burton
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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13
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Berry V, Ionides A, Pontikos N, Georgiou M, Yu J, Ocaka LA, Moore AT, Quinlan RA, Michaelides M. The genetic landscape of crystallins in congenital cataract. Orphanet J Rare Dis 2020; 15:333. [PMID: 33243271 PMCID: PMC7691105 DOI: 10.1186/s13023-020-01613-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 11/10/2020] [Indexed: 02/01/2023] Open
Abstract
Background The crystalline lens is mainly composed of a large family of soluble proteins called the crystallins, which are responsible for its development, growth, transparency and refractive index. Disease-causing sequence variants in the crystallins are responsible for nearly 50% of all non-syndromic inherited congenital cataracts, as well as causing cataract associated with other diseases, including myopathies. To date, more than 300 crystallin sequence variants causing cataract have been identified. Methods Here we aimed to identify the genetic basis of disease in five multi-generation British families and five sporadic cases with autosomal dominant congenital cataract using whole exome sequencing, with identified variants validated using Sanger sequencing. Following bioinformatics analysis, rare or novel variants with a moderate to damaging pathogenicity score, were filtered out and tested for segregation within the families. Results We have identified 10 different heterozygous crystallin variants. Five recurrent variants were found: family-A, with a missense variant (c.145C>T; p.R49C) in CRYAA associated with nuclear cataract; family-B, with a deletion in CRYBA1 (c.272delGAG; p.G91del) associated with nuclear cataract; and family-C, with a truncating variant in CRYGD (c.470G>A; W157*) causing a lamellar phenotype; individuals I and J had variants in CRYGC (c.13A>C; T5P) and in CRYGD (c.418C>T; R140*) causing unspecified congenital cataract and nuclear cataract, respectively. Five novel disease-causing variants were also identified: family D harboured a variant in CRYGC (c.179delG; R60Qfs*) responsible for a nuclear phenotype; family E, harboured a variant in CRYBB1 (c.656G>A; W219*) associated with lamellar cataract; individual F had a variant in CRYGD (c.392G>A; W131*) associated with nuclear cataract; and individuals G and H had variants in CRYAA (c.454delGCC; A152del) and in CRYBB1 (c.618C>A; Y206*) respectively, associated with unspecified congenital cataract. All novel variants were predicted to be pathogenic and to be moderately or highly damaging. Conclusions We report five novel variants and five known variants. Some are rare variants that have been reported previously in small ethnic groups but here we extend this to the wider population and record a broader phenotypic spectrum for these variants.
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Affiliation(s)
- Vanita Berry
- Department of Genetics, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK. .,Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK.
| | - Alex Ionides
- Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK
| | - Nikolas Pontikos
- Department of Genetics, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK
| | - Michalis Georgiou
- Department of Genetics, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK
| | - Jing Yu
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU, UK
| | - Louise A Ocaka
- GOSgene, Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, WC1N 1EH, UK
| | - Anthony T Moore
- Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK.,Ophthalmology Department, University of California School of Medicine, San Francisco, CA, 94158, USA
| | - Roy A Quinlan
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, Durham, DH1 3LE, UK
| | - Michel Michaelides
- Department of Genetics, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK. .,Moorfields Eye Hospital NHS Foundation Trust, London, EC1V 2PD, UK.
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14
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Bashir S, Shamsi A, Ahmad F, Hassan MI, Kamal MA, Islam A. Biophysical Elucidation of Fibrillation Inhibition by Sugar Osmolytes in α-Lactalbumin: Multispectroscopic and Molecular Docking Approaches. ACS OMEGA 2020; 5:26871-26882. [PMID: 33111013 PMCID: PMC7581248 DOI: 10.1021/acsomega.0c04062] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 09/25/2020] [Indexed: 05/02/2023]
Abstract
Protein aggregation is among the most challenging new frontiers in protein chemistry as well as in molecular medicine and has direct implications in protein misfolding. This study investigated the role of sugar molecules (glucose, fructose, sucrose, and the mixture of glucose and fructose) in protecting the structural integrity of α-lactalbumin (α-LA) against aggregation. The research focused here is the inhibitory capabilities of sugars against α-LA fibril formation investigated employing diverse multispectroscopic and microscopic techniques. The aggregation was induced in α-LA thermally with a change in concentration. UV-vis spectroscopy, ThT binding assay, Trp fluorescence, Rayleigh scattering, and turbidity assay depicted synchronized results. Further, transmission electron microscopy (TEM) complemented that a mixture of glucose and fructose was the best inhibitor of α-LA fibril formation. Inhibition of α-LA aggregation by sugar osmolytes is attributed to the formation of hydrogen bonds between these osmolytes, as evidenced by the molecular docking results. This hydrogen bonding is a key player that prevents aggregation in α-LA in the presence of sugar osmolytes. This study provides an insight into the ability of naturally occurring sugar osmolytes to inhibit fibril formation and can serve as a platform to treat protein misfolding and aggregation-oriented disorders.
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Affiliation(s)
- Sania Bashir
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Anas Shamsi
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Faizan Ahmad
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Md. Imtaiyaz Hassan
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Mohammad Azhar Kamal
- Department
of Biochemistry, College of Science, University
of Jeddah, Jeddah 21589, Saudi Arabia
- University
of Jeddah Centre for Scientific and Medical Research (UJ-CSMR), University
of Jeddah, Jeddah 21589, Saudi Arabia
| | - Asimul Islam
- Centre
for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
- Correspondence:
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15
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Shamsi A, Ahmed A, Khan MS, Husain FM, Bano B. Rosmarinic acid restrains protein glycation and aggregation in human serum albumin: Multi spectroscopic and microscopic insight - Possible Therapeutics Targeting Diseases. Int J Biol Macromol 2020; 161:187-193. [PMID: 32526295 DOI: 10.1016/j.ijbiomac.2020.06.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/19/2020] [Accepted: 06/05/2020] [Indexed: 12/30/2022]
Abstract
Protein aggregation and glycation are directly associated with many pathological conditions including several neurodegenerative disorders. This study investigates the potential of naturally occurring plant product, Rosmarinic acid (RA), to inhibit the glycation and aggregation process. In this study, we report that varying concentrations of methylglyoxal (MG) induce advanced glycation end products (AGEs) and aggregates formation in HSA in vitro on day 6 and day 8, respectively. AGEs specific fluorescence confirmed the formation of AGEs in HSA in the presence of MG and further characterized the inhibitory potential of RA. It was found that the presence of RA prevented AGEs formation in vitro. Further, aggregates of HSA were characterized employing multi spectroscopic and microscopic techniques and RA was found to inhibit this process. This study proposes that RA could be a potential natural molecule to treat disorders where AGEs and aggregates of proteins play a pivotal role.
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Affiliation(s)
- Anas Shamsi
- Department of Biochemistry, Aligarh Muslim University, Aligarh, India
| | - Azaj Ahmed
- Department of Biochemistry, Aligarh Muslim University, Aligarh, India
| | - Mohd Shahnawaz Khan
- Department of Biochemistry, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia
| | - Fohad Mabood Husain
- Department of Food Science and Nutrition, Faculty of Food and Agricultural Sciences, King Saud University, Riyadh 11451, Saudi Arabia
| | - Bilqees Bano
- Department of Biochemistry, Aligarh Muslim University, Aligarh, India.
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16
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Ram L, Mittal C, Harsolia RS, Yadav JK. Trehalose Inhibits the Heat-Induced Formation of the Amyloid-Like Structure of Soluble Proteins Isolated from Human Cataract Lens. Protein J 2020; 39:509-518. [PMID: 33037983 DOI: 10.1007/s10930-020-09919-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2020] [Indexed: 11/25/2022]
Abstract
The age-dependent loss of solubility and aggregation of crystallins constitute the pathological hallmarks of cataract. Several biochemical and biophysical factors are responsible for the reduction of crystallins' solubility and formation of irreversible protein aggregates, which display amyloid-like characteristics. The present study reports the heat-induced aggregation of soluble proteins isolated from human cataract lenses and the formation of amyloid-like structures. Exposure of protein at 55 °C for 4 h resulted in extensive (≈ 60%) protein aggregation. The heat-induced protein aggregates displayed substantial (≈ 20 nm) redshift in the wavelength of maximum absorption (λmax) of Congo red (CR) and increase in Thioflavin T (ThT) fluorescence emission intensity, indicating the presence of amyloid-like structures in the heat-induced protein aggregates. Subsequently, the addition of trehalose resulted in substantial inhibition of heat-induced aggregation and the formation of amyloid-like structure. The ability of trehalose to inhibit the heat-induced aggregation was found to be linearly dependent upon its concentration used. The optimum effect was observed in the presence of 30-40% (w/v) trehalose where the aggregated was found to be reduced from 60 to 30%. The present study demonstrated the ability to trehalose to inhibit the protein aggregation and interfere with the formation of amyloid-like structures.
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Affiliation(s)
- Lakshman Ram
- Department of Biotechnology, Central University of Rajasthan, NH-8 Bandersindri, Kishangarh, Ajmer, Rajasthan, 305817, India
| | - Chandrika Mittal
- Department of Biotechnology, Central University of Rajasthan, NH-8 Bandersindri, Kishangarh, Ajmer, Rajasthan, 305817, India
| | - Ram Swaroop Harsolia
- Department of Ophthalmology, Jawaharlal Nehru Medical College, Ajmer, Rajasthan, India
| | - Jay Kant Yadav
- Department of Biotechnology, Central University of Rajasthan, NH-8 Bandersindri, Kishangarh, Ajmer, Rajasthan, 305817, India.
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17
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Sharma V, Sharma S, Rana S, Ghosh KS. Inhibition of amyloid fibrillation of human γD-crystallin by gold nanoparticles: Studies at molecular level. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 233:118199. [PMID: 32151988 DOI: 10.1016/j.saa.2020.118199] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
The capability of citrate-stabilized gold nanoparticles (AuNps) has been explored for the inhibition of amyloid fibrillation of human γD-crystallin (HGD), a major protein of eye lens. Citrate-capped AuNps were synthesized, characterized and used further for amyloid inhibition. The results from intrinsic and extrinsic (in the presence of Thioflavin T and ANS) fluorescence based assays and CD spectroscopy clearly suggest that AuNps at nanomolar concentrations can act as an effective inhibitor against fibrillation of HGD. Fluorescence microscopic and transmission electron microscopic images also supported this observation. Considering the inhibitory role of AuNps against HGD fibrillation, interactions between HGD and AuNps were studied to decipher the mechanism of amyloid inhibition. The binding and quenching constants were calculated as ~109 M-1 using the data of tryptophan fluorescence quenching of HGD by AuNps. Ground state complexation between the protein and nanoparticles was predicted. AuNps were not found to cause any major conformational changes in the native protein. Entropy-driven complexation process between the protein and nanoparticles indicates the interactions of AuNps with hydrophobic residues of HGD. Therefore, in the presence of AuNps, the exposure of the hydrophobic patches of HGD during its partial unfolding became restricted, which results inhibition in HGD fibrillation.
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Affiliation(s)
- Vandna Sharma
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Shivani Sharma
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India.
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18
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Rana S, Ghosh KS. Inhibition of fibrillation of human γd-crystallin by a flavonoid morin. J Biomol Struct Dyn 2020; 39:4279-4289. [PMID: 32469293 DOI: 10.1080/07391102.2020.1775701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To inhibit the formation of amyloid fibrils by human γd-crystallin (HGD), a series of four flavonoids (quercertin, rutin, morin and hesperetin) was tested. Only morin had demonstrated significant inhibition of HGD fibrillation. Results from fluorimetric assay techniques (using thioflavin T and ANS), FTIR, circular dichroism and microscopic imaging (fluorescence microscopy and transmission electron microscopy) confirmed HGD fibrillation inhibition by morin. HGD-morin complex formation at ground state resulted tryptophan fluorescence quenching through static mechanism, which was also confirmed by determining the excited-state life time of HGD tryptophan residues. Förster resonance energy transfer occurs from HGD to morin. Synchronous, three-dimensional fluorescence, FTIR and circular dichroism results suggest that major changes in HGD conformation did not occur on binding with morin. The interactions between HGD and morin involve hydrogen bonding and/or van der Waals forces. Docking predictions also support experimental results.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, Himachal Pradesh, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, Himachal Pradesh, India
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19
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Abstract
The crystallins (α, β and γ), major constituent proteins of eye lens fiber cells play their critical role in maintaining the transparency and refractive index of the lens. Under different stress factors and with aging, β- and γ-crystallins start to unfold partially leading to their aggregation. Protein aggregation in lens basically enhances light scattering and causes the vision problem, commonly known as cataract. α-crystallin as a molecular chaperone forms complexes with its substrates (β- and γ-crystallins) to prevent such aggregation. In this chapter, the structural features of β- and γ-crystallins have been discussed. Detailed structural information linked with the high stability of γC-, γD- and γS-crystallins have been incorporated. The nature of homologous and heterologous interactions among crystallins has been deciphered, which are involved in their molecular association and complex formation.
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Affiliation(s)
- Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India.
| | - Priyanka Chauhan
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India
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20
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Sprague-Piercy MA, Wong E, Roskamp KW, Fakhoury JN, Freites JA, Tobias DJ, Martin RW. Human αB-crystallin discriminates between aggregation-prone and function-preserving variants of a client protein. Biochim Biophys Acta Gen Subj 2019; 1864:129502. [PMID: 31812542 DOI: 10.1016/j.bbagen.2019.129502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/17/2019] [Accepted: 12/03/2019] [Indexed: 01/01/2023]
Abstract
BACKGROUND The eye lens crystallins are highly soluble proteins that are required to last the lifespan of an organism due to low protein turnover in the lens. Crystallin aggregation leads to formation of light-scattering aggregates known as cataract. The G18V mutation of human γS-crystallin (γS-G18V), which is associated with childhood-onset cataract, causes structural changes throughout the N-terminal domain and increases aggregation propensity. The holdase chaperone protein αB-crystallin does not interact with wild-type γS-crystallin, but does bind its G18V variant. The specific molecular determinants of αB-crystallin binding to client proteins is incompletely charcterized. Here, a new variant of γS, γS-G18A, was created to test the limits of αB-crystallin selectivity. METHODS Molecular dynamics simulations were used to investigate the structure and dynamics of γS-G18A. The overall fold of γS-G18A was assessed by circular dichroism (CD) spectroscopy and intrinsic tryptophan fluorescence. Its thermal unfolding temperature and aggregation propensity were characterized by CD and DLS, respectively. Solution-state NMR was used to characterize interactions between αB-crystallin and γS-G18A. RESULTS γS-G18A exhibits minimal structural changes, but has compromised thermal stability relative to γS-WT. The placement of alanine, rather than valine, at this highly conserved glycine position produces minor changes in hydrophobic surface exposure. However, human αB-crystallin does not bind the G18A variant, in contrast to previous observations for γS-G18V, which aggregates at physiological temperature. CONCLUSIONS αB-crystallin is capable of distinguishing between aggregation-prone and function-preserving variants, and recognizing the transient unfolding or minor conformers that lead to aggregation in the disease-related variant. GENERAL SIGNIFICANCE Human αB-crystallin distinguishes between highly similar variants of a structural crystallin, binding the cataract-related γS-G18V variant, but not the function-preserving γS-G18A variant, which is monomeric at physiological temperature.
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Affiliation(s)
- Marc A Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, United States of America
| | - Eric Wong
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America
| | - Kyle W Roskamp
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America
| | - Joseph N Fakhoury
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America
| | - J Alfredo Freites
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America
| | - Douglas J Tobias
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America.
| | - Rachel W Martin
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America; Department of Molecular Biology and Biochemistry, UC Irvine, Irvine, CA 92697, United States of America.
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21
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Devitt G, Rice W, Crisford A, Nandhakumar I, Mudher A, Mahajan S. Conformational Evolution of Molecular Signatures during Amyloidogenic Protein Aggregation. ACS Chem Neurosci 2019; 10:4593-4611. [PMID: 31661242 DOI: 10.1021/acschemneuro.9b00451] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Aggregation is a pathological hallmark of proteinopathies such as Alzheimer's disease and results in the deposition of β-sheet-rich amyloidogenic protein aggregates. Such proteinopathies can be classified by the identity of one or more aggregated proteins, with recent evidence also suggesting that distinct molecular conformers (strains) of the same protein can be observed in different diseases, as well is in subtypes of the same disease. Therefore, methods for the quantification of pathological changes in protein conformation are central to understanding and treating proteinopathies. In this work, the evolution of Raman spectroscopic molecular signatures of three conformationally distinct proteins, bovine serum albumin (α-helical-rich), β2-microglobulin (β-sheet-rich), and tau (natively disordered), was assessed during aggregation into oligomers and fibrils. The morphological evolution was tracked using atomic force microscopy and corresponding conformational changes were assessed by their Raman signatures acquired in both wet and dried conditions. A deconvolution model was developed which allowed us to quantify the conformation of the nonregular protein tau, as well as for the oligomeric and fibrillar species of each of the proteins. Principle component analysis of the fingerprint region allowed further identification of the distinguishing spectral features and unsupervised distinction. While an increase in β-sheet is seen on aggregation, crucially, however, each protein also retains a significant proportion of its native monomeric structure after aggregation. Thus, spectral analysis of each aggregated species, oligomeric, as well as fibrillar, for each protein resulted in a unique and quantitative "conformational fingerprint". This approach allowed us to provide the first differential detection of both oligomers and fibrils of the three different amyloidogenic proteins, including tau, whose aggregates have never before been interrogated using spontaneous Raman spectroscopy. Quantitative "conformational fingerprinting" by Raman spectroscopy thus demonstrates its huge potential and utility in understanding proteinopathic disease mechanisms and for providing strain-specific early diagnostic markers and targets for disease-modifying therapies.
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22
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Yang W, Tan P, Fu X, Hong L. Prediction of amyloid aggregation rates by machine learning and feature selection. J Chem Phys 2019; 151:084106. [PMID: 31470712 DOI: 10.1063/1.5113848] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A novel data-based machine learning algorithm for predicting amyloid aggregation rates is reported in this paper. Based on a highly nonlinear projection from 16 intrinsic features of a protein and 4 extrinsic features of the environment to the protein aggregation rate, a feedforward fully connected neural network (FCN) with one hidden layer is trained on a dataset composed of 21 different kinds of amyloid proteins and tested on 4 rest proteins. FCN shows a much better performance than traditional algorithms, such as multivariable linear regression and support vector regression, with an average accuracy higher than 90%. Furthermore, by the correlation analysis and the principal component analysis, seven key features, folding energy, HP patterns for helix, sheet and helices cross membrane, pH, ionic strength, and protein concentration, are shown to constitute a minimum feature set for characterizing the amyloid aggregation kinetics.
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Affiliation(s)
- Wuyue Yang
- Zhou Pei-Yuan Center for Applied Mathematics, Tsinghua University, Beijing 100084, China
| | - Pengzhen Tan
- Zhou Pei-Yuan Center for Applied Mathematics, Tsinghua University, Beijing 100084, China
| | - Xianjun Fu
- Institute for Literature and Culture of Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250355, China
| | - Liu Hong
- Zhou Pei-Yuan Center for Applied Mathematics, Tsinghua University, Beijing 100084, China
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23
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Precupas A, Leonties AR, Neacsu A, Sandu R, Popa VT. Gallic acid influence on bovine serum albumin thermal stability. NEW J CHEM 2019. [DOI: 10.1039/c9nj00115h] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A thermoanalytical approach reveals the dual action of GA on BSA thermal stability.
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Affiliation(s)
- Aurica Precupas
- “Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy
- 060021 – Bucharest
- Romania
| | - Anca Ruxandra Leonties
- “Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy
- 060021 – Bucharest
- Romania
| | - Andreea Neacsu
- “Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy
- 060021 – Bucharest
- Romania
| | - Romica Sandu
- “Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy
- 060021 – Bucharest
- Romania
| | - Vlad Tudor Popa
- “Ilie Murgulescu” Institute of Physical Chemistry of the Romanian Academy
- 060021 – Bucharest
- Romania
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24
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RETRACTED: Peptide-induced formation of protein aggregates and amyloid fibrils in human and guinea pig αA-crystallins under physiological conditions of temperature and pH. Exp Eye Res 2018; 179:193-205. [PMID: 30448341 DOI: 10.1016/j.exer.2018.11.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 10/17/2018] [Accepted: 11/14/2018] [Indexed: 02/07/2023]
Abstract
This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).
This article has been retracted at the request of the authors. The senior author contacted the journal in a forthright manner, in an effort to preserve the scientific integrity of the literature, after discovering a significant error in the results reported in the article. The authors were recently made aware of a paper by Kim et al. (Nature Commun. 2019) which shows a spirosome structure (the enzyme aldehyde-alcohol dehydrogenase) present in E. coli (Fig. 5a) that is very similar to the structure the authors thought formed when synthetic alpha A crystallin (66-80) peptide was incubated for 24 h with recombinant guinea pig alpha A insert crystallin (see Kumarasamy et al., Figs. 7C and F, and Fig. 9). Subsequent to publication of their report, the authors later found a number of images that showed what appeared to be the same structure present in samples of their presumably purified recombinant guinea pig alpha A insert crystallin which had been incubated without peptide for 24 h. Hence, the authors now conclude that the structures shown in Figs. 7C and F, and Fig. 9 of their article published in this journal are actually due to E. coli contaminant aldehyde-alcohol dehydrogenase. The authors deeply regret this error and any inconvenience it may have caused.
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Domínguez-Calva JA, Pérez-Vázquez ML, Serebryany E, King JA, Quintanar L. Mercury-induced aggregation of human lens γ-crystallins reveals a potential role in cataract disease. J Biol Inorg Chem 2018; 23:1105-1118. [DOI: 10.1007/s00775-018-1607-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 08/22/2018] [Indexed: 01/17/2023]
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26
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Chemerovski-Glikman M, Mimouni M, Dagan Y, Haj E, Vainer I, Allon R, Blumenthal EZ, Adler-Abramovich L, Segal D, Gazit E, Zayit-Soudry S. Rosmarinic Acid Restores Complete Transparency of Sonicated Human Cataract Ex Vivo and Delays Cataract Formation In Vivo. Sci Rep 2018; 8:9341. [PMID: 29921877 PMCID: PMC6008418 DOI: 10.1038/s41598-018-27516-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 05/22/2018] [Indexed: 12/31/2022] Open
Abstract
Cataract, the leading cause of vision impairment worldwide, arises from abnormal aggregation of crystallin lens proteins. Presently, surgical removal is the only therapeutic approach. Recent findings have triggered renewed interest in development of non-surgical treatment alternatives. However, emerging treatments are yet to achieve full and consistent lens clearance. Here, the first ex vivo assay to screen for drug candidates that reduce human lenticular protein aggregation was developed. This assay allowed the identification of two leading compounds as facilitating the restoration of nearly-complete transparency of phacoemulsified cataractous preparation ex vivo. Mechanistic studies demonstrated that both compounds reduce cataract microparticle size and modify their amyloid-like features. In vivo studies confirmed that the lead compound, rosmarinic acid, delays cataract formation and reduces the severity of lens opacification in model rats. Thus, the ex vivo assay may provide an initial platform for broad screening of potential novel therapeutic agents towards pharmacological treatment of cataract.
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Affiliation(s)
- Marina Chemerovski-Glikman
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Michael Mimouni
- Department of Ophthalmology, Rambam Health Care Campus, Technion Israel Institute of Technology, Haifa, Israel
| | - Yarden Dagan
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Esraa Haj
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Igor Vainer
- Department of Ophthalmology, Rambam Health Care Campus, Technion Israel Institute of Technology, Haifa, Israel
| | - Raviv Allon
- Department of Ophthalmology, Rambam Health Care Campus, Technion Israel Institute of Technology, Haifa, Israel
| | - Eytan Z Blumenthal
- Department of Ophthalmology, Rambam Health Care Campus, Technion Israel Institute of Technology, Haifa, Israel
| | - Lihi Adler-Abramovich
- Department of Oral Biology, The Goldschleger School of Dental Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Daniel Segal
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, 69978, Israel
- Sagol Interdisciplinary School of Neurosciences, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, 69978, Israel.
- Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| | - Shiri Zayit-Soudry
- Department of Ophthalmology, Rambam Health Care Campus, Technion Israel Institute of Technology, Haifa, Israel.
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27
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Lee CT, Terentjev EM. Mechanisms and rates of nucleation of amyloid fibrils. J Chem Phys 2018; 147:105103. [PMID: 28915747 DOI: 10.1063/1.4995255] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The classical nucleation theory finds the rate of nucleation proportional to the monomer concentration raised to the power, which is the "critical nucleus size," nc. The implicit assumption, that amyloids nucleate in the same way, has been recently challenged by an alternative two-step mechanism, when the soluble monomers first form a metastable aggregate (micelle) and then undergo conversion into the conformation rich in β-strands that are able to form a stable growing nucleus for the protofilament. Here we put together the elements of extensive knowledge about aggregation and nucleation kinetics, using a specific case of Aβ1-42 amyloidogenic peptide for illustration, to find theoretical expressions for the effective rate of amyloid nucleation. We find that at low monomer concentrations in solution and also at low interaction energy between two peptide conformations in the micelle, the nucleation occurs via the classical route. At higher monomer concentrations, and a range of other interaction parameters between peptides, the two-step "aggregation-conversion" mechanism of nucleation takes over. In this regime, the effective rate of the process can be interpreted as a power of monomer concentration in a certain range of parameters; however, the exponent is determined by a complicated interplay of interaction parameters and is not related to the minimum size of the growing nucleus (which we find to be ∼7-8 for Aβ1-42).
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Affiliation(s)
- Cheng-Tai Lee
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Eugene M Terentjev
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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28
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Sharma V, Ghosh KS. Inhibition of amyloid fibrillation and destabilization of fibrils of human γD-crystallin by direct red 80 and orange G. Int J Biol Macromol 2017; 105:956-964. [DOI: 10.1016/j.ijbiomac.2017.07.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 11/24/2022]
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29
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Ghaffari Sharaf M, Cetinel S, Semenchenko V, Damji KF, Unsworth LD, Montemagno C. Peptides for targeting βB2-crystallin fibrils. Exp Eye Res 2017; 165:109-117. [PMID: 28986145 DOI: 10.1016/j.exer.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 09/20/2017] [Accepted: 10/01/2017] [Indexed: 01/24/2023]
Abstract
Crystallins are a major family of proteins located within the lens of the eye. Cataracts are thought to be due to the formation of insoluble fibrillar aggregates, which are largely composed of proteins from the crystallin family. Today the only cataract treatment that exists is surgery and this can be difficult to access for individuals in the developing world. Development of novel pharmacotherapeutic approaches for the treatment of cataract rests on the specific targeting of these structures. βB2-crystallin, a member of β-crystallin family, is a large component of the crystallin proteins within the lens, and as such was used to form model fibrils in vitro. Peptides were identified, using phage display techniques, that bound to these fibrils with high affinity. Fibrillation of recombinantly expressed human βB2-crystallin was performed in 10% (v/v) trifluoroethanol (TFE) solution (pH 2.0) at various temperatures, and its amyloid-like structure was confirmed using Thioflavin-T (ThT) assay, transmission electron microscopy (TEM), and X-ray fiber diffraction (XRFD) analysis. Affinity of identified phage-displayed peptides were analyzed using enzyme-linked immunosorbent assay (ELISA). Specific binding of a cyclic peptide (CKQFKDTTC) showed the highest affinity, which was confirmed using a competitive inhibition assay.
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Affiliation(s)
- Mehdi Ghaffari Sharaf
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada; Ingenuity Lab, University of Alberta, Edmonton, AB, Canada
| | - Sibel Cetinel
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada; Ingenuity Lab, University of Alberta, Edmonton, AB, Canada
| | - Valentyna Semenchenko
- National Institute of Nanotechnology, National Research Council, Edmonton, AB, Canada
| | - Karim F Damji
- Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, AB, Canada
| | - Larry D Unsworth
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada; National Institute of Nanotechnology, National Research Council, Edmonton, AB, Canada.
| | - Carlo Montemagno
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada; National Institute of Nanotechnology, National Research Council, Edmonton, AB, Canada; Ingenuity Lab, University of Alberta, Edmonton, AB, Canada.
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30
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Whitley MJ, Xi Z, Bartko JC, Jensen MR, Blackledge M, Gronenborn AM. A Combined NMR and SAXS Analysis of the Partially Folded Cataract-Associated V75D γD-Crystallin. Biophys J 2017; 112:1135-1146. [PMID: 28355541 DOI: 10.1016/j.bpj.2017.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/03/2017] [Accepted: 02/08/2017] [Indexed: 11/19/2022] Open
Abstract
A cataract is a pathological condition characterized by the clouding of the normally clear eye lens brought about by deposition of crystallin proteins in the lens fiber cells. These protein aggregates reduce visual acuity by scattering or blocking incoming light. Chemical damage to proteins of the crystallin family, accumulated over a lifetime, leads to age-related cataract, whereas inherited mutations are associated with congenital or early-onset cataract. The V75D mutant of γD-crystallin is associated with congenital cataract in mice and was previously shown to un/fold via a partially folded intermediate. Here, we structurally characterized the stable equilibrium urea unfolding intermediate of V75D at the ensemble level using solution NMR and small-angle x-ray scattering. Our data show that, in the intermediate, the C-terminal domain retains a folded conformation that is similar to the native wild-type protein, whereas the N-terminal domain is unfolded and comprises an ensemble of random conformers, without any detectable residual structural propensities.
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Affiliation(s)
- Matthew J Whitley
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Zhaoyong Xi
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jonathan C Bartko
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | | | - Martin Blackledge
- Institut de Biologie Structurale, CEA, CNRS, Université Grenoble Alpes, Grenoble, France
| | - Angela M Gronenborn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
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31
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Sen S, Chakraborty M, Goley S, Dasgupta S, DasGupta S. Fibrillar disruption by AC electric field induced oscillation: A case study with human serum albumin. Biophys Chem 2017; 226:23-33. [DOI: 10.1016/j.bpc.2017.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 11/25/2022]
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32
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Yamazaki H, Beniash E, Yamakoshi Y, Simmer JP, Margolis HC. Protein Phosphorylation and Mineral Binding Affect the Secondary Structure of the Leucine-Rich Amelogenin Peptide. Front Physiol 2017; 8:450. [PMID: 28706493 PMCID: PMC5489624 DOI: 10.3389/fphys.2017.00450] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 06/14/2017] [Indexed: 12/31/2022] Open
Abstract
Previously, we have shown that serine-16 phosphorylation in native full-length porcine amelogenin (P173) and the Leucine-Rich Amelogenin Peptide (LRAP(+P)), an alternative amelogenin splice product, affects protein assembly and mineralization in vitro. Notably, P173 and LRAP(+P) stabilize amorphous calcium phosphate (ACP) and inhibit hydroxyapatite (HA) formation, while non-phosphorylated counterparts (rP172, LRAP(-P)) guide the growth of ordered bundles of HA crystals. Based on these findings, we hypothesize that the phosphorylation of full-length amelogenin and LRAP induces conformational changes that critically affect its capacity to interact with forming calcium phosphate mineral phases. To test this hypothesis, we have utilized Fourier transform infrared spectroscopy (FTIR) to determine the secondary structure of LRAP(-P) and LRAP(+P) in the absence/presence of calcium and selected mineral phases relevant to amelogenesis; i.e., hydroxyapatite (HA: an enamel crystal prototype) and (ACP: an enamel crystal precursor phase). Aqueous solutions of LRAP(-P) or LRAP(+P) were prepared with or without 7.5 mM of CaCl2 at pH 7.4. FTIR spectra of each solution were obtained using attenuated total reflectance, and amide-I peaks were analyzed to provide secondary structure information. Secondary structures of LRAP(+P) and LRAP(-P) were similarly assessed following incubation with suspensions of HA and pyrophosphate-stabilized ACP. Amide I spectra of LRAP(-P) and LRAP(+P) were found to be distinct from each other in all cases. Spectra analyses showed that LRAP(-P) is comprised mostly of random coil and β-sheet, while LRAP(+P) exhibits more β-sheet and α-helix with little random coil. With added Ca, the random coil content increased in LRAP(-P), while LRAP(+P) exhibited a decrease in α-helix components. Incubation of LRAP(-P) with HA or ACP resulted in comparable increases in β-sheet structure. Notably, however, LRAP(+P) secondary structure was more affected by ACP, primarily showing an increase in β-sheet structure, compared to that observed with added HA. These collective findings indicate that phosphorylation induces unique secondary structural changes that may enhance the functional capacity of native phosphorylated amelogenins like LRAP to stabilize an ACP precursor phase during early stages of enamel mineral formation.
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Affiliation(s)
- Hajime Yamazaki
- Center for Biomineralization, The Forsyth InstituteCambridge, MA, United States.,Department of Developmental Biology, Harvard School of Dental MedicineBoston, MA, United States
| | - Elia Beniash
- Department of Oral Biology, Center for Craniofacial Regeneration, McGowan Institute for Regenerative Medicine, University of PittsburghPittsburgh, PA, United States
| | - Yasuo Yamakoshi
- Department of Biochemistry and Molecular Biology, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of DentistryAnn Arbor, MI, United States
| | - Henry C Margolis
- Center for Biomineralization, The Forsyth InstituteCambridge, MA, United States.,Department of Developmental Biology, Harvard School of Dental MedicineBoston, MA, United States
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33
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Roskamp KW, Montelongo DM, Anorma CD, Bandak DN, Chua JA, Malecha KT, Martin RW. Multiple Aggregation Pathways in Human γS-Crystallin and Its Aggregation-Prone G18V Variant. Invest Ophthalmol Vis Sci 2017; 58:2397-2405. [PMID: 28444328 PMCID: PMC5407245 DOI: 10.1167/iovs.16-20621] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Purpose Cataract results from the formation of light-scattering precipitates due to point mutations or accumulated damage in the structural crystallins of the eye lens. Although excised cataracts are predominantly amorphous, in vitro studies show that crystallins are capable of adopting a variety of morphologies depending on the preparation method. Here we characterize thermal, pH-dependent, and UV-irradiated aggregates from wild-type human γS-crystallin (γS-WT) and its aggregation-prone variant, γS-G18V. Methods Aggregates of γS-WT and γS-G18V were prepared under acidic, neutral, and basic pH conditions and held at 25°C or 37°C for 48 hours. UV-induced aggregates were produced by irradiation with a 355-nm laser. Aggregation and fibril formation were monitored via turbidity and thioflavin T (ThT) assays. Aggregates were characterized using intrinsic aromatic fluorescence, powder x-ray diffraction, and mass spectrometry. Results γS-crystallin aggregates displayed different characteristics depending on the preparation method. γS-G18V produced a larger amount of detectable aggregates than did γS-WT and at less-extreme conditions. Aggregates formed under basic and acidic conditions yielded elevated ThT fluorescence; however, aggregates formed at low pH did not produce strongly turbid solutions. UV-induced aggregates produced highly turbid solutions but displayed only moderate ThT fluorescence. X-ray diffraction confirms amyloid character in low-pH samples and UV-irradiated samples, although the relative amounts vary. Conclusions γS-G18V demonstrates increased aggregation propensity compared to γS-WT when treated with heat, acid, or UV light. The resulting aggregates differ in their ThT fluorescence and turbidity, suggesting that at least two different aggregation pathways are accessible to both proteins under the conditions tested.
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Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry, University of California, Irvine, Irvine, California, United States
| | - David M Montelongo
- Department of Chemistry, University of California, Irvine, Irvine, California, United States
| | - Chelsea D Anorma
- Department of Chemistry, University of California, Irvine, Irvine, California, United States
| | - Diana N Bandak
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California, United States
| | - Janine A Chua
- Department of Chemistry, University of California, Irvine, Irvine, California, United States
| | - Kurtis T Malecha
- Department of Chemistry, University of California, Irvine, Irvine, California, United States
| | - Rachel W Martin
- Department of Chemistry, University of California, Irvine, Irvine, California, United States 2Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California, United States
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34
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Zhang TO, Alperstein AM, Zanni MT. Amyloid β-Sheet Secondary Structure Identified in UV-Induced Cataracts of Porcine Lenses using 2D IR Spectroscopy. J Mol Biol 2017; 429:1705-1721. [PMID: 28454743 PMCID: PMC5493149 DOI: 10.1016/j.jmb.2017.04.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 04/08/2017] [Accepted: 04/24/2017] [Indexed: 02/04/2023]
Abstract
Cataracts are formed by the aggregation of crystallin proteins in the eye lens. Many in vitro studies have established that crystallin proteins precipitate into aggregates that contain amyloid fibers when denatured, but there is little evidence that ex vivo cataracts contain amyloid. In this study, we collect two-dimensional infrared (2D IR) spectra on tissue slices of porcine eye lenses. As shown in control experiments on in vitro αB- and γD-crystallin, 2D IR spectroscopy can identify the highly ordered β-sheets typical of amyloid secondary structure even if the fibers themselves are too short to be resolved with TEM. In ex vivo experiments of acid-treated tissues, characteristic 2D IR features are observed and fibers >50nm in length are resolved by transmission electron microscopy (TEM), consistent with amyloid fibers. In UV-irradiated lens tissues, fibers are not observed with TEM, but highly ordered β-sheets of amyloid secondary structure is identified from the 2D IR spectra. The characteristic 2D IR features of amyloid β-sheet secondary structure are created by as few as four or five strands and so identify amyloid secondary structure even if the aggregates themselves are too small to be resolved with TEM. We discuss these findings in the context of the chaperone system of the lens, which we hypothesize sequesters small aggregates, thereby preventing long fibers from forming. This study expands the scope of heterodyned 2D IR spectroscopy to tissues. The results provide a link between in vitro and ex vivo studies and support the hypothesis that cataracts are an amyloid disease.
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Affiliation(s)
- Tianqi O Zhang
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
| | - Ariel M Alperstein
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
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35
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Hall D, Zhao R, So M, Adachi M, Rivas G, Carver JA, Goto Y. Recognizing and analyzing variability in amyloid formation kinetics: Simulation and statistical methods. Anal Biochem 2016; 510:56-71. [PMID: 27430932 DOI: 10.1016/j.ab.2016.07.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 12/24/2022]
Abstract
We examine the phenomenon of variability in the kinetics of amyloid formation and detail methods for its simulation, identification and analysis. Simulated data, reflecting intrinsic variability, were produced using rate constants, randomly sampled from a pre-defined distribution, as parameters in an irreversible nucleation-growth kinetic model. Simulated kinetic traces were reduced in complexity through description in terms of three characteristic parameters. Practical methods for assessing convergence of the reduced parameter distributions were introduced and a bootstrap procedure was applied to determine convergence for different levels of intrinsic variation. Statistical methods for assessing the significance of shifts in parameter distributions, relating to either change in parameter mean or distribution shape, were tested. Robust methods for analyzing and interpreting kinetic data possessing significant intrinsic variance will allow greater scrutiny of the effects of anti-amyloid compounds in drug trials.
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Affiliation(s)
- Damien Hall
- Research School of Chemistry, Australian National University, Acton ACT 2601, Australia; Institute for Protein Research, Osaka University, 3-1- Yamada-oka, Suita, Osaka 565-0871 Japan.
| | - Ran Zhao
- Research School of Chemistry, Australian National University, Acton ACT 2601, Australia
| | - Masatomo So
- Institute for Protein Research, Osaka University, 3-1- Yamada-oka, Suita, Osaka 565-0871 Japan
| | - Masayuki Adachi
- Institute for Protein Research, Osaka University, 3-1- Yamada-oka, Suita, Osaka 565-0871 Japan
| | - Germán Rivas
- Centro de Investigaciones Biológicas, CSIC, 28006 Madrid, Spain
| | - John A Carver
- Research School of Chemistry, Australian National University, Acton ACT 2601, Australia
| | - Yuji Goto
- Institute for Protein Research, Osaka University, 3-1- Yamada-oka, Suita, Osaka 565-0871 Japan
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36
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Bag S, Chaudhury S, Pramanik D, DasGupta S, Dasgupta S. Hydrophobic tail length plays a pivotal role in amyloid beta (25-35) fibril-surfactant interactions. Proteins 2016; 84:1213-23. [DOI: 10.1002/prot.25069] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/05/2016] [Accepted: 05/12/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Sudipta Bag
- Department of Chemistry; Indian Institute of Technology Kharagpur; Kharagpur 721302 India
| | | | - Dibyendu Pramanik
- Department of Chemistry; Indian Institute of Technology Kharagpur; Kharagpur 721302 India
| | - Sunando DasGupta
- Department of Chemical Engineering; Indian Institute of Technology Kharagpur; Kharagpur 721302 India
| | - Swagata Dasgupta
- Department of Chemistry; Indian Institute of Technology Kharagpur; Kharagpur 721302 India
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37
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Serebryany E, Takata T, Erickson E, Schafheimer N, Wang Y, King JA. Aggregation of Trp > Glu point mutants of human gamma-D crystallin provides a model for hereditary or UV-induced cataract. Protein Sci 2016; 25:1115-28. [PMID: 26991007 DOI: 10.1002/pro.2924] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 12/21/2022]
Abstract
Numerous mutations and covalent modifications of the highly abundant, long-lived crystallins of the eye lens cause their aggregation leading to progressive opacification of the lens, cataract. The nature and biochemical mechanisms of the aggregation process are poorly understood, as neither amyloid nor native-state polymers are commonly found in opaque lenses. The βγ-crystallin fold contains four highly conserved buried tryptophans, which can be oxidized to more hydrophilic products, such as kynurenine, upon UV-B irradiation. We mimicked this class of oxidative damage using Trp→Glu point mutants of human γD-crystallin. Such substitutions may represent a model of UV-induced photodamage-introduction of a charged group into the hydrophobic core generating "denaturation from within." The effects of Trp→Glu substitutions were highly position dependent. While each was destabilizing, only the two located in the bottom of the double Greek key fold-W42E and W130E-yielded robust aggregation of partially unfolded intermediates at 37°C and pH 7. The αB-crystallin chaperone suppressed aggregation of W130E, but not W42E, indicating distinct aggregation pathways from damage in the N-terminal vs C-terminal domain. The W130E aggregates had loosely fibrillar morphology, yet were nonamyloid, noncovalent, showed little surface hydrophobicity, and formed at least 20°C below the melting temperature of the native β-sheets. These features are most consistent with domain-swapped polymerization. Aggregation of partially destabilized crystallins under physiological conditions, as occurs in this class of point mutants, could provide a simple in vitro model system for drug discovery and optimization.
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Affiliation(s)
- Eugene Serebryany
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Takumi Takata
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Erika Erickson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Nathaniel Schafheimer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Yongting Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
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38
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Xi YB, Chen XJ, Zhao WJ, Yan YB. Congenital Cataract-Causing Mutation G129C in γC-Crystallin Promotes the Accumulation of Two Distinct Unfolding Intermediates That Form Highly Toxic Aggregates. J Mol Biol 2015; 427:2765-81. [DOI: 10.1016/j.jmb.2015.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/18/2015] [Accepted: 07/01/2015] [Indexed: 10/23/2022]
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39
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Wu JW, Chen ME, Wen WS, Chen WA, Li CT, Chang CK, Lo CH, Liu HS, Wang SSS. Comparative analysis of human γD-crystallin aggregation under physiological and low pH conditions. PLoS One 2014; 9:e112309. [PMID: 25389780 PMCID: PMC4229192 DOI: 10.1371/journal.pone.0112309] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 10/04/2014] [Indexed: 11/19/2022] Open
Abstract
Cataract, a major cause of visual impairment worldwide, is the opacification of the eye’s crystalline lens due to aggregation of the crystallin proteins. The research reported here is aimed at investigating the aggregating behavior of γ-crystallin proteins in various incubation conditions. Thioflavin T binding assay, circular dichroism spectroscopy, 1-anilinonaphthalene-8-sulfonic acid fluorescence spectroscopy, intrinsic (tryptophan) fluorescence spectroscopy, light scattering, and electron microscopy were used for structural characterization. Molecular dynamics simulations and bioinformatics prediction were performed to gain insights into the γD-crystallin mechanisms of fibrillogenesis. We first demonstrated that, except at pH 7.0 and 37°C, the aggregation of γD-crystallin was observed to be augmented upon incubation, as revealed by turbidity measurements. Next, the types of aggregates (fibrillar or non-fibrillar aggregates) formed under different incubation conditions were identified. We found that, while a variety of non-fibrillar, granular species were detected in the sample incubated under pH 7.0, the fibrillogenesis of human γD-crystallin could be induced by acidic pH (pH 2.0). In addition, circular dichroism spectroscopy, 1-anilinonaphthalene-8-sulfonic acid fluorescence spectroscopy, and intrinsic fluorescence spectroscopy were used to characterize the structural and conformational features in different incubation conditions. Our results suggested that incubation under acidic condition led to a considerable change in the secondary structure and an enhancement in solvent-exposure of the hydrophobic regions of human γD-crystallin. Finally, molecular dynamics simulations and bioinformatics prediction were performed to better explain the differences between the structures and/or conformations of the human γD-crystallin samples and to reveal potential key protein region involved in the varied aggregation behavior. Bioinformatics analyses revealed that the initiation of amyloid formation of human γD-crystallin may be associated with a region within the C-terminal domain. We believe the results from this research may contribute to a better understanding of the possible mechanisms underlying the pathogenesis of senile nuclear cataract.
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Affiliation(s)
- Josephine W. Wu
- Department of Optometry, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan
- * E-mail: (JWW); (SSW)
| | - Mei-Er Chen
- Department of Entomology, National Chung Hsing University, Taichung 402, Taiwan
| | - Wen-Sing Wen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Wei-An Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chien-Ting Li
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chih-Kai Chang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Chun-Hsien Lo
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Hwai-Shen Liu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Steven S.-S. Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
- * E-mail: (JWW); (SSW)
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40
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Crowded milieu prevents fibrillation of hen egg white lysozyme with retention of enzymatic activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:8-16. [DOI: 10.1016/j.jphotobiol.2014.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 11/18/2022]
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41
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Ghosh S, Pandey NK, Banerjee P, Chaudhury K, Nagy NV, Dasgupta S. Copper(II) directs formation of toxic amorphous aggregates resulting in inhibition of hen egg white lysozyme fibrillation under alkaline salt-mediated conditions. J Biomol Struct Dyn 2014; 33:991-1007. [PMID: 24806136 DOI: 10.1080/07391102.2014.921864] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hen egg white lysozyme (HEWL) adopts a molten globule-like state at high pH (~12.75) and is found to form amyloid fibrils at alkaline pH. Here, we report that Cu(II) inhibits self-association of HEWL at pH 12.75 both at 37 and 65 °C. A significant reduction in Thioflavin T fluorescence intensity, attenuation in β-sheet content and reduction in hydrophobic exposure were observed with increasing Cu(II) stoichiometry. Electron paramagnetic resonance spectroscopy suggests a 4N type of coordination pattern around Cu(II) during fibrillation. Cu(II) is also capable of altering the cytotoxicity of the proteinaceous aggregates. Fibrillar species of diverse morphology were found in the absence of Cu(II) with the generation of amorphous aggregates in the presence of Cu(II), which are more toxic compared to the fibrils alone.
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Affiliation(s)
- Sudeshna Ghosh
- a Department of Chemistry , Indian Institute of Technology , Kharagpur 721302 , India
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42
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Serebryany E, King JA. The βγ-crystallins: native state stability and pathways to aggregation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:32-41. [PMID: 24835736 DOI: 10.1016/j.pbiomolbio.2014.05.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 01/26/2023]
Abstract
The βγ-crystallins are among the most stable and long-lived proteins in the human body. With increasing age, however, they transform to high molecular weight light-scattering aggregates, resulting in cataracts. This occurs despite the presence in the lens of high concentrations of the a-crystallin chaperones. Aggregation of crystallins can be induced in vitro by a variety of stresses, including acidic pH, ultraviolet light, oxidative damage, heating or freezing, and specific amino acid substitutions. Accumulating evidence points to the existence of specific biochemical pathways of protein: protein interaction and polymerization. We review the methods used for studying crystallin stability and aggregation and discuss the sometimes counterintuitive relationships between factors that favor native state stability and those that favor non-native aggregation. We discuss the behavior of βγ-crystallins in mixtures and their chaperone ability; the consequences of missense mutations and covalent damage to the side-chains; and the evolutionary strategies that have shaped these proteins. Efforts are ongoing to reveal the nature of cataractous crystallin aggregates and understand the mechanisms of aggregation in the context of key models of protein polymerization: amyloid, native-state, and domain-swapped. Such mechanistic understanding is likely to be of value for the development of therapeutic interventions and draw attention to unanswered questions about the relationship between a protein's native state stability and its transformation to an aggregated state.
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Affiliation(s)
- Eugene Serebryany
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States.
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43
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Mohr BG, Dobson CM, Garman SC, Muthukumar M. Electrostatic origin of in vitro aggregation of human γ-crystallin. J Chem Phys 2014; 139:121914. [PMID: 24089726 DOI: 10.1063/1.4816367] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The proteins α-, β-, and γ-crystallins are the major components of the lens in the human eye. Using dynamic light scattering method, we have performed in vitro investigations of protein-protein interactions in dilute solutions of human γ-crystallin and α-crystallin. We find that γ-crystallin spontaneously aggregates into finite-sized clusters in phosphate buffer solutions. There are two distinct populations of unaggregated and aggregated γ-crystallins in these solutions. On the other hand, α-crystallin molecules are not aggregated into large clusters in solutions of α-crystallin alone. When α-crystallin and γ-crystallin are mixed in phosphate buffer solutions, we demonstrate that the clusters of γ-crystallin are prevented. By further investigating the roles of temperature, protein concentration, pH, salt concentration, and a reducing agent, we show that the aggregation of γ-crystallin under our in vitro conditions arises from non-covalent electrostatic interactions. In addition, we show that aggregation of γ-crystallin occurs under the dilute in vitro conditions even in the absence of oxidizing agents that can induce disulfide cross-links, long considered to be responsible for human cataracts. Aggregation of γ-crystallin when maintained under reducing conditions suggests that oxidation does not contribute to the aggregation in dilute solutions.
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Affiliation(s)
- Benjamin G Mohr
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Schafheimer N, Wang Z, Schey K, King J. Tyrosine/cysteine cluster sensitizing human γD-crystallin to ultraviolet radiation-induced photoaggregation in vitro. Biochemistry 2014; 53:979-90. [PMID: 24410332 PMCID: PMC3954642 DOI: 10.1021/bi401397g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
![]()
Ultraviolet
radiation (UVR) exposure is a major risk factor for
age-related cataract, a protein-aggregation disease of the human lens
often involving the major proteins of the lens, the crystallins. γD-Crystallin
(HγD-Crys) is abundant in the nucleus of the human lens, and
its folding and aggregation have been extensively studied. Previous
work showed that HγD-Crys photoaggregates in vitro upon exposure
to UVA/UVB light and that its conserved tryptophans are not required
for aggregation. Surprisingly, the tryptophan residues play a photoprotective
role because of a distinctive energy-transfer mechanism. HγD-Crys
also contains 14 tyrosine residues, 12 of which are organized as six
pairs. We investigated the role of the tyrosines of HγD-Crys
by replacing pairs with alanines and monitoring photoaggregation using
light scattering and SDS-PAGE. Mutating both tyrosines in the Y16/Y28
pair to alanine slowed the formation of light-scattering aggregates.
Further mutant studies implicated Y16 as important for photoaggregation.
Mass spectrometry revealed that C18, in contact with Y16, is heavily
oxidized during UVR exposure. Analysis of multiple mutant proteins
by mass spectrometry suggested that Y16 and C18 likely participate
in the same photochemical process. The data suggest an initial photoaggregation
pathway for HγD-Crys in which excited-state Y16 interacts with
C18, initiating radical polymerization.
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Affiliation(s)
- Nathaniel Schafheimer
- Department of Biology, Massachusetts Institute of Technology , 68-330, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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45
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Moran SD, Zhang TO, Zanni MT. An alternative structural isoform in amyloid-like aggregates formed from thermally denatured human γD-crystallin. Protein Sci 2014; 23:321-31. [PMID: 24415662 DOI: 10.1002/pro.2422] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/06/2014] [Accepted: 01/08/2014] [Indexed: 11/11/2022]
Abstract
The eye lens protein γD-crystallin contributes to cataract formation in the lens. In vitro experiments show that γD-crystallin has a high propensity to form amyloid fibers when denatured, and that denaturation by acid or UV-B photodamage results in its C-terminal domain forming the β-sheet core of amyloid fibers. Here, we show that thermal denaturation results in sheet-like aggregates that contain cross-linked oligomers of the protein, according to transmission electron microscopy and SDS-PAGE. We use two-dimensional infrared spectroscopy to show that these aggregates have an amyloid-like secondary structure with extended β-sheets, and use isotope dilution experiments to show that each protein contributes approximately one β-strand to each β-sheet in the aggregates. Using segmental (13) C labeling, we show that the organization of the protein's two domains in thermally induced aggregates results in a previously unobserved structure in which both the N-terminal and C-terminal domains contribute to β-sheets. We propose a model for the structural organization of the aggregates and attribute the recruitment of the N-terminal domain into the fiber structure to intermolecular cross linking.
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Affiliation(s)
- Sean D Moran
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
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46
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Michael R, Otto C, Lenferink A, Gelpi E, Montenegro GA, Rosandić J, Tresserra F, Barraquer RI, Vrensen GFJM. Absence of amyloid-beta in lenses of Alzheimer patients: a confocal Raman microspectroscopic study. Exp Eye Res 2013; 119:44-53. [PMID: 24333259 DOI: 10.1016/j.exer.2013.11.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/15/2013] [Accepted: 11/26/2013] [Indexed: 12/13/2022]
Abstract
We have compared the protein profiles in plaques and tangles in the hippocampus of post-mortem Alzheimer brains and in opaque and clear regions in the deep cortex of eye lenses of the same donors. From the 7 Alzheimer donors studied, 1 had pronounced bilateral cortical lens opacities, 1 moderate and 5 only minor or no cortical opacities. We focused on beta-sheet levels, a hallmarking property of amyloid-beta, the major protein of plaques and tau protein, the major protein of tangles in Alzheimer brains. Confocal Raman microspectroscopy and imaging was used in combination with hierarchical cluster analysis. Plaques and tangles show high levels of beta-sheets with a beta-sheet to protein ratio of 1.67. This ratio is 1.12 in unaffected brain tissue surrounding the plaques and tangles. In the lenses this ratio is 1.17 independently of the presence or absence of opacities. This major difference in beta-sheet conformation between hippocampus and lens is supported by Congo red and immunostaining of amyloid-beta and tau which were positive for plaques and tangles in the hippocampus but fully negative for the lens irrespective of the presence or absence of opacities. In line with a previous study (Michael et al., 2013) we conclude that cortical lens opacities are not typical for Alzheimer patients and are not hallmarked by accumulation of amyloid-beta, and can thus not be considered as predictors or indicators of Alzheimer disease as claimed by Goldstein et al. (2003).
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Affiliation(s)
- Ralph Michael
- Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain; University Eye Clinic, Paracelsus Medical University, Salzburg, Austria.
| | - Cees Otto
- Medical Cell Bio Physics, University of Twente, Enschede, The Netherlands
| | - Aufried Lenferink
- Medical Cell Bio Physics, University of Twente, Enschede, The Netherlands
| | - Ellen Gelpi
- Neurological Tissue Bank of the Biobanc-Hospital Clinic-Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Gustavo A Montenegro
- Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jurja Rosandić
- Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | - Rafael I Barraquer
- Institut Universitari Barraquer, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Gijs F J M Vrensen
- Department of Ophthalmology, Leiden University Medical Center, The Netherlands
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47
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Pandey NK, Ghosh S, Dasgupta S. Fructose restrains fibrillogenesis in human serum albumin. Int J Biol Macromol 2013; 61:424-32. [DOI: 10.1016/j.ijbiomac.2013.08.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 08/07/2013] [Accepted: 08/08/2013] [Indexed: 11/17/2022]
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48
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Moran SD, Zhang TO, Decatur SM, Zanni MT. Amyloid fiber formation in human γD-Crystallin induced by UV-B photodamage. Biochemistry 2013; 52:6169-81. [PMID: 23957864 DOI: 10.1021/bi4008353] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
γD-Crystallin is an abundant structural protein of the lens that is found in native and modified forms in cataractous aggregates. We establish that UV-B irradiation of γD-Crystallin leads to structurally specific modifications and precipitation via two mechanisms: amorphous aggregates and amyloid fibers. UV-B radiation causes cleavage of the backbone, in large measure near the interdomain interface, where side chain oxidations are also concentrated. 2D IR spectroscopy and expressed protein ligation localize fiber formation exclusively to the C-terminal domain of γD-Crystallin. The native β-sandwich domains are not retained upon precipitation by either mechanism. The similarities between the amyloid forming pathways when induced by either UV-B radiation or low pH suggest that the propensity for the C-terminal β-sandwich domain to form amyloid β-sheets determines the misfolding pathway independent of the mechanism of denaturation.
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Affiliation(s)
- Sean D Moran
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, WI, United States 53706
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49
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Bhattacharya M, Jain N, Dogra P, Samai S, Mukhopadhyay S. Nanoscopic Amyloid Pores Formed via Stepwise Protein Assembly. J Phys Chem Lett 2013; 4:480-485. [PMID: 26281744 DOI: 10.1021/jz3019786] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Protein aggregation leading to various nanoscale assemblies is under scrutiny due to its implications in a broad range of human diseases. In the present study, we have used ovalbumin, a model non-inhibitory serpin, to elucidate the molecular events involved in amyloid assembly using a diverse array of spectroscopic and imaging tools such as fluorescence, laser Raman, circular dichroism spectroscopy, and atomic force microscopy (AFM). The AFM images revealed a progressive morphological transition from spherical oligomers to nanoscopic annular pores that further served as templates for higher-order supramolecular assembly into larger amyloid pores. Raman spectroscopic investigations illuminated in-depth molecular details into the secondary structural changes of the protein during amyloid assembly and pore formation. Additionally, Raman measurements indicated the presence of antiparallel β-sheets in the amyloid core. Overall, our studies revealed that the protein conformational switch in the context of the oligomers triggers the hierarchical assembly into nanoscopic amyloid pores. Our results will have broad implications in the structural characterization of amyloid pores derived from a variety of disease-related proteins.
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Affiliation(s)
- Mily Bhattacharya
- †Department of Chemical Sciences and ‡Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali-140306, India
| | - Neha Jain
- †Department of Chemical Sciences and ‡Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali-140306, India
| | - Priyanka Dogra
- †Department of Chemical Sciences and ‡Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali-140306, India
| | - Soumyadyuti Samai
- †Department of Chemical Sciences and ‡Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali-140306, India
| | - Samrat Mukhopadhyay
- †Department of Chemical Sciences and ‡Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali-140306, India
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50
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Ghosh S, Pandey NK, Dasgupta S. (-)-Epicatechin gallate prevents alkali-salt mediated fibrillogenesis of hen egg white lysozyme. Int J Biol Macromol 2012; 54:90-8. [PMID: 23219698 DOI: 10.1016/j.ijbiomac.2012.11.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/28/2012] [Accepted: 11/28/2012] [Indexed: 01/26/2023]
Abstract
Green tea polyphenols (GTPs) are found to be potent inhibitors of amyloid fibril formation. We report the effective inhibitory property of (-)-epicatechin gallate (ECG) during the alkali-salt induced fibrillogenesis of hen egg white lysozyme (HEWL) at 37 °C. Spectroscopic techniques such as fluorescence, circular dichroism and microscopic images show that (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) show moderate inhibition of fibrillation with ECG as the most potent polyphenol. Aromatic interactions, hydrophobic interactions, the radical scavenging activity and autoxidation of polyphenols are likely to be the major reasons for ECG being the most effective inhibitor.
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Affiliation(s)
- Sudeshna Ghosh
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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