1
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Sun J, Morishima K, Inoue R, Sugiyama M, Takata T. Characterization of βB2-crystallin tryptophan mutants reveals two different folding states in solution. Protein Sci 2024; 33:e5092. [PMID: 38924206 PMCID: PMC11201810 DOI: 10.1002/pro.5092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024]
Abstract
Conserved tryptophan residues are critical for the structure and the stability of β/γ-crystallin in the lenses of vertebrates. During aging, in which the lenses are continuously exposed to ultraviolet irradiation and other environmental stresses, oxidation of tryptophan residues in β/γ-crystallin is triggered and impacts the lens proteins to varying degrees. Kynurenine derivatives, formed by oxidation of tryptophan, accumulate, resulting in destabilization and insolubilization of β/γ-crystallin, which correlates with age-related cataract formation. To understand the contribution of tryptophan modification on the structure and stability of human βB2-crystallin, five tryptophan residues were mutated to phenylalanine considering its similarity in structure and hydrophilicity to kynurenine. Among all mutants, W59F and W151F altered the stability and homo-oligomerization of βB2-crystallin-W59F promoted tetramerization whereas W151F blocked oligomerization. Most W59F dimers transformed into tetramer in a month, and the separated dimer and tetramer of W59F demonstrated different structures and hydrophobicity, implying that the biochemical properties of βB2-crystallin vary over time. By using SAXS, we found that the dimer of βB2-crystallin in solution resembled the lattice βB1-crystallin dimer (face-en-face), whereas the tetramer of βB2-crystallin in solution resembled its lattice tetramer (domain-swapped). Our results suggest that homo-oligomerization of βB2-crystallin includes potential inter-subunit reactions, such as dissociation, unfolding, and re-formation of the dimers into a tetramer in solution. The W>F mutants are useful in studying different folding states of βB2-crystallin in lens.
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Affiliation(s)
- Jiayue Sun
- Department of Chemistry, Graduate School of ScienceKyoto UniversityKyotoJapan
| | - Ken Morishima
- Institute for Integrated Radiation and Nuclear ScienceKyoto UniversityOsakaJapan
| | - Rintaro Inoue
- Institute for Integrated Radiation and Nuclear ScienceKyoto UniversityOsakaJapan
| | - Masaaki Sugiyama
- Institute for Integrated Radiation and Nuclear ScienceKyoto UniversityOsakaJapan
| | - Takumi Takata
- Institute for Integrated Radiation and Nuclear ScienceKyoto UniversityOsakaJapan
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2
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Hill JA, Nyathi Y, Horrell S, von Stetten D, Axford D, Owen RL, Beddard GS, Pearson AR, Ginn HM, Yorke BA. An ultraviolet-driven rescue pathway for oxidative stress to eye lens protein human gamma-D crystallin. Commun Chem 2024; 7:81. [PMID: 38600176 PMCID: PMC11006947 DOI: 10.1038/s42004-024-01163-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/27/2024] [Indexed: 04/12/2024] Open
Abstract
Human gamma-D crystallin (HGD) is a major constituent of the eye lens. Aggregation of HGD contributes to cataract formation, the leading cause of blindness worldwide. It is unique in its longevity, maintaining its folded and soluble state for 50-60 years. One outstanding question is the structural basis of this longevity despite oxidative aging and environmental stressors including ultraviolet radiation (UV). Here we present crystallographic structures evidencing a UV-induced crystallin redox switch mechanism. The room-temperature serial synchrotron crystallographic (SSX) structure of freshly prepared crystallin mutant (R36S) shows no post-translational modifications. After aging for nine months in the absence of light, a thiol-adduct (dithiothreitol) modifying surface cysteines is observed by low-dose SSX. This is shown to be UV-labile in an acutely light-exposed structure. This suggests a mechanism by which a major source of crystallin damage, UV, may also act as a rescuing factor in a finely balanced redox system.
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Affiliation(s)
- Jake A Hill
- School of Chemistry and Biosciences, University of Bradford, Richmond Road, Bradford, BD7 1DP, United Kingdom
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Yvonne Nyathi
- Faculty of Biological Sciences, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Sam Horrell
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - David von Stetten
- European Molecular Biology Laboratory, Notkestraße 85, 22607, Hamburg, Germany
| | - Danny Axford
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Robin L Owen
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Godfrey S Beddard
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Arwen R Pearson
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany
| | - Helen M Ginn
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany.
- Center for Free-Electron Laser Science, CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
| | - Briony A Yorke
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom.
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3
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Parisi E, Adorinni S, Garcia AM, Kralj S, De Zorzi R, Marchesan S. Self-assembling tripeptide forming water-bound channels and hydrogels. J Pept Sci 2023; 29:e3524. [PMID: 37226306 DOI: 10.1002/psc.3524] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/26/2023]
Abstract
D-Ser(tBu)-L-Phe-L-Trp is described as a self-assembling tripeptide that yields nanofibrillar hydrogels at physiological conditions (phosphate buffer at pH 7.4). The peptide is characterized by several spectroscopic methods, such as circular dichroism and fluorescence, oscillatory rheometry, and transmission electron microscopy. Single-crystal X-ray diffraction reveals supramolecular packing into water-bound channels and allows the visualization of the intermolecular interactions holding together peptide stacks.
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Affiliation(s)
- Evelina Parisi
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
| | - Simone Adorinni
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
| | - Ana M Garcia
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
| | - Slavko Kralj
- Department for Materials Synthesis, Jožef Stefan Institute, Ljubljana, Slovenia
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Rita De Zorzi
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
| | - Silvia Marchesan
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
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4
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Membrane cholesterol modulates the dynamics and depth of penetration of κ-casein. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Highly Sensitive Tryptophan Fluorescence Probe for detecting Rhythmic Conformational changes of KaiC in the Cyanobacterial Circadian Clock System. Biochem J 2022; 479:1505-1515. [PMID: 35771042 PMCID: PMC9342895 DOI: 10.1042/bcj20210544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 11/17/2022]
Abstract
KaiC, a core protein of the cyanobacterial circadian clock, consists of an N-terminal CI domain and a C-terminal CII domain, and assembles into a double-ring hexamer upon binding with ATP. KaiC rhythmically phosphorylates and dephosphorylates its own two adjacent residues Ser431 and Thr432 at the CII domain with a period of approximately 24h through assembly and disassembly with the other clock proteins, KaiA and/or KaiB. In this study, to understand how KaiC alters its conformation as the source of circadian rhythm, we investigated structural changes of an inner-radius side of the CII ring using time-resolved Trp fluorescence spectroscopy. A KaiC mutant harboring a Trp fluorescence probe at a position of 419 exhibited a robust circadian rhythm with little temperature sensitivity in the presence of KaiA and KaiB. Our fluorescence observations show a remarkable environmental change at the inner-radius side of the CII ring during circadian oscillation. Crystallographic analysis revealed that a side chain of Trp at the position of 419 was oriented toward a region undergoing a helix-coil transition, which is considered to be a key event to allosterically regulate the CI ring that plays a crucial role in determining the cycle period. The present study provides a dynamical insight into how KaiC generates circadian oscillation.
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6
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Li H, Yu Y, Ruan M, Jiao F, Chen H, Gao J, Weng Y, Bao Y. The mechanism for thermal-enhanced chaperone-like activity of α-crystallin against UV irradiation-induced aggregation of γD-crystallin. Biophys J 2022; 121:2233-2250. [PMID: 35619565 DOI: 10.1016/j.bpj.2022.05.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/11/2022] [Accepted: 05/20/2022] [Indexed: 11/18/2022] Open
Abstract
Exposure to solar UV irradiation damages γ-crystallin, leading to cataract formation via aggregation. α-Crystallin, as a small heat-shock protein (sHsps), efficiently suppresses this irreversible aggregation by selectively binding the denatured γ-crystallin monomer. In this study, liquid chromatography tandem mass spectrometry (LC-MS) was used to evaluate UV-325 nm irradiation-induced photodamage of human γD-crystallin in the presence of bovine α-crystallin, atomic force microscope (AFM) and dynamic light scattering (DLS) techniques were used to detect the quaternary structure changes of α-crystallin oligomer, and Fourier transform infrared (FTIR) spectroscopy and temperature-jump (T-jump) nanosecond time-resolved IR absorbance difference spectroscopy were used to probe the secondary structure changes of bovine α-crystallin. We find that the thermal-induced subunit dissociation of α-crystallin oligomer involves the breaking of hydrogen bonds at the dimeric interface, leading to three different spectral components at varied temperature regions as resolved from temperature-dependent IR spectra. Under UV-325 nm irradiation, unfolded γD-crystallin binds to the dissociated α-crystallin subunit to form αγ-complex, then follows the reassociation of αγ-complex to the partially dissociated α-crystallin oligomer. This prevents the aggregation of denatured γD-crystallin. The formation of the γD-bound α-crystallin oligomer is further confirmed by AFM and DLS analysis, which reveals an obvious size expansion in the reassociated αγ-oligomers. In addition, UV-325 nm irradiation causes a peptide bond cleavage of γD-crystallin at Ala158 in presence of α-crystallin. Our results suggest a very effective protection mechanism for subunits dissociated from α-crystallin oligomers against UV irradiation-induced aggregation of γD-crystallin, at an expense of a loss of a short C-terminal peptide in γD-crystallin.
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Affiliation(s)
- Hao Li
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; College of Chemical Biology and Biotechnology, Beijing University Shenzhen Graduate School, Shenzhen, China; Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yingying Yu
- Department of Ophthalmology, Peking University People's Hospital, Eye Diseases and Optometry Institute, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, College of Optometry, Peking University Health Science Center, Beijing, China
| | - Meixia Ruan
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Fang Jiao
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Hailong Chen
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jiali Gao
- College of Chemical Biology and Biotechnology, Beijing University Shenzhen Graduate School, Shenzhen, China; Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Yuxiang Weng
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Yongzhen Bao
- Department of Ophthalmology, Peking University People's Hospital, Eye Diseases and Optometry Institute, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, College of Optometry, Peking University Health Science Center, Beijing, China.
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7
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Ren L, Hu L, Zhang Y, Liu J, Xu W, Wu W, Xu J, Chen X, Yao K, Yu Y. Cataract-Causing S93R Mutant Destabilized Structural Conformation of βB1 Crystallin Linking With Aggregates Formation and Cellular Viability. Front Mol Biosci 2022; 9:844719. [PMID: 35359596 PMCID: PMC8964140 DOI: 10.3389/fmolb.2022.844719] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/22/2022] [Indexed: 12/14/2022] Open
Abstract
Cataract, opacity of the eye lens, is the leading cause of visual impairment worldwide. The crucial pathogenic factors that cause cataract are misfolding and aggregation of crystallin protein. βB1-crystallin, which is the most abundant water-soluble protein in mammalian lens, is essential for lens transparency. A previous study identified the missense mutation βB1-S93R being responsible for congenital cataract. However, the exact pathogenic mechanism causing cataract remains unclear. The S93 residue, which is located at the first Greek-key motif of βB1-crystallin, is highly conserved, and its substitution to Arginine severely impaired hydrogen bonds and structural conformation, which were evaluated via Molecular Dynamic Simulation. The βB1-S93R was also found to be prone to aggregation in both human cell lines and Escherichia coli. Then, we isolated the βB1-S93R variant from inclusion bodies by protein renaturation. The βB1-S93R mutation exposed more hydrophobic residues, and the looser structural mutation was prone to aggregation. Furthermore, the S93R mutation reduced the structural stability of βB1-crystallin when incubated at physiological temperature and made it more sensitive to environmental stress, such as UV irradiation or oxidative stress. We also constructed a βB1-S93R cellular model and discovered that βB1-S93R was more sensitive to environmental stress, causing not only aggregate formation but also cellular apoptosis and impaired cellular viability. All of the results indicated that lower solubility and structural stability, sensitivity to environmental stress, vulnerability to aggregation, and impaired cellular viability of βB1-S93R might be involved in cataract development.
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Affiliation(s)
- Ling Ren
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lidan Hu
- National Clinical Research Center for Child Health, The Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ying Zhang
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Liu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Eye Center of Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wanyue Xu
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yibo Yu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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8
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Norton-Baker B, Rocha MA, Granger-Jones J, Fishman DA, Martin RW. Human γS-Crystallin Resists Unfolding Despite Extensive Chemical Modification from Exposure to Ionizing Radiation. J Phys Chem B 2022; 126:679-690. [PMID: 35021623 PMCID: PMC9977691 DOI: 10.1021/acs.jpcb.1c08157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionizing radiation has dramatic effects on living organisms, causing damage to proteins, DNA, and other cellular components. γ radiation produces reactive oxygen species (ROS) that damage biological macromolecules. Protein modification due to interactions with hydroxyl radical is one of the most common deleterious effects of radiation. The human eye lens is particularly vulnerable to the effects of ionizing radiation, as it is metabolically inactive and its proteins are not recycled after early development. Therefore, radiation damage accumulates and eventually can lead to cataract formation. Here we explore the impact of γ radiation on a long-lived structural protein. We exposed the human eye lens protein γS-crystallin (HγS) to high doses of γ radiation and investigated the chemical and structural effects. HγS accumulated many post-translational modifications (PTMs), appearing to gain significant oxidative damage. Biochemical assays suggested that cysteines were affected, with the concentration of free thiol reduced with increasing γ radiation exposure. SDS-PAGE analysis showed that irradiated samples form protein-protein cross-links, including nondisulfide covalent bonds. Tandem mass spectrometry on proteolytic digests of irradiated samples revealed that lysine, methionine, tryptophan, leucine, and cysteine were oxidized. Despite these chemical modifications, HγS remained folded past 10.8 kGy of γ irradiation as evidenced by circular dichroism and intrinsic tryptophan fluorescence spectroscopy.
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Affiliation(s)
- Brenna Norton-Baker
- These authors contributed equally.,Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
| | - Megan A. Rocha
- These authors contributed equally.,Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
| | | | - Dmitry A. Fishman
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA,Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, USA
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9
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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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10
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Serebryany E, Thorn DC, Quintanar L. Redox chemistry of lens crystallins: A system of cysteines. Exp Eye Res 2021; 211:108707. [PMID: 34332989 PMCID: PMC8511183 DOI: 10.1016/j.exer.2021.108707] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/09/2021] [Accepted: 07/23/2021] [Indexed: 11/28/2022]
Abstract
The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the β- and α-crystallins where pertinent.
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Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, Mexico
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11
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A Closer Examination of 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate Amino Acid Derivatization in HPLC with Multiple Detection Modes. Chromatographia 2021. [DOI: 10.1007/s10337-021-04051-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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12
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Rocha MA, Sprague-Piercy MA, Kwok AO, Roskamp KW, Martin RW. Chemical Properties Determine Solubility and Stability in βγ-Crystallins of the Eye Lens. Chembiochem 2021; 22:1329-1346. [PMID: 33569867 PMCID: PMC8052307 DOI: 10.1002/cbic.202000739] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Indexed: 11/10/2022]
Abstract
βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.
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Affiliation(s)
- Megan A. Rocha
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Marc A. Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| | - Ashley O. Kwok
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
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13
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Wang KJ, Liao XY, Lin K, Xi YB, Wang S, Wan XH, Yan YB. A novel F30S mutation in γS-crystallin causes autosomal dominant congenital nuclear cataract by increasing susceptibility to stresses. Int J Biol Macromol 2021; 172:475-482. [PMID: 33454329 DOI: 10.1016/j.ijbiomac.2021.01.079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/03/2021] [Accepted: 01/12/2021] [Indexed: 01/14/2023]
Abstract
Despite of increasingly accumulated genetic variations of autosomal dominant congenital cataracts (ADCC), the causative genes of many ADCC patients remains unknown. In this research, we identified a novel F30S mutation in γS-crystallin from a three-generation Chinese family with ADCC. The patients possessing the F30S mutation exhibited nuclear cataract phenotype. The potential molecular mechanism underlying ADCC by the F30S mutation was investigated by comparing the structural features, stability and aggregatory potency of the mutated protein with the wild type protein. Spectroscopic experiments indicated that the F30S mutation did not affect γS-crystallin secondary structure compositions, but modified the microenvironments around aromatic side-chains. Thermal and chemical denaturation studies indicated that the mutation destabilized the protein and increased its aggregatory potency. The mutation altered the two-state unfolding of γS-crystallin to a three-state unfolding with the accumulation of an unfolding intermediate. The almost identical values in the changes of Gibbs free energies for transitions from the native state to intermediate and from the intermediate to unfolded state suggested that the mutation probably disrupted the cooperativity between the two domains during unfolding. Our results expand the genetic variation map of ADCC and provide novel insights into the molecular mechanism underlying ADCC caused by mutations in β/γ-crystallins.
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Affiliation(s)
- Kai-Jie Wang
- Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China
| | - Xiao-Yan Liao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Kunxia Lin
- Ophthalmology Department, Fujian Provincial Hospital, Fuzhou, 350001, China
| | - Yi-Bo Xi
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sha Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiu-Hua Wan
- Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
| | - Yong-Bin Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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14
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Cao S, Li H, Zhao Z, Zhang S, Chen J, Xu J, Knutson JR, Brand L. Ultrafast Fluorescence Spectroscopy via Upconversion and Its Applications in Biophysics. Molecules 2021; 26:molecules26010211. [PMID: 33401638 PMCID: PMC7794851 DOI: 10.3390/molecules26010211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 11/25/2022] Open
Abstract
In this review, the experimental set-up and functional characteristics of single-wavelength and broad-band femtosecond upconversion spectrophotofluorometers developed in our laboratory are described. We discuss applications of this technique to biophysical problems, such as ultrafast fluorescence quenching and solvation dynamics of tryptophan, peptides, proteins, reduced nicotinamide adenine dinucleotide (NADH), and nucleic acids. In the tryptophan dynamics field, especially for proteins, two types of solvation dynamics on different time scales have been well explored: ~1 ps for bulk water, and tens of picoseconds for “biological water”, a term that combines effects of water and macromolecule dynamics. In addition, some proteins also show quasi-static self-quenching (QSSQ) phenomena. Interestingly, in our more recent work, we also find that similar mixtures of quenching and solvation dynamics occur for the metabolic cofactor NADH. In this review, we add a brief overview of the emerging development of fluorescent RNA aptamers and their potential application to live cell imaging, while noting how ultrafast measurement may speed their optimization.
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Affiliation(s)
- Simin Cao
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
| | - Haoyang Li
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
| | - Zenan Zhao
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
| | - Sanjun Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
| | - Jinquan Chen
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
| | - Jianhua Xu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China; (S.C.); (H.L.); (Z.Z.); (S.Z.); (J.C.)
- Correspondence: (J.X.); (J.R.K.); Tel.: +86-21-6223-3936 (J.X.); +1-301-496-2557 (J.R.K.)
| | - Jay R. Knutson
- Laboratory for Advanced Microscopy and Biophotonics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Correspondence: (J.X.); (J.R.K.); Tel.: +86-21-6223-3936 (J.X.); +1-301-496-2557 (J.R.K.)
| | - Ludwig Brand
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA;
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15
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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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16
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Maksimov EG, Protasova EA, Tsoraev GV, Yaroshevich IA, Maydykovskiy AI, Shirshin EA, Gostev TS, Jelzow A, Moldenhauer M, Slonimskiy YB, Sluchanko NN, Friedrich T. Probing of carotenoid-tryptophan hydrogen bonding dynamics in the single-tryptophan photoactive Orange Carotenoid Protein. Sci Rep 2020; 10:11729. [PMID: 32678150 PMCID: PMC7366913 DOI: 10.1038/s41598-020-68463-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 06/25/2020] [Indexed: 01/07/2023] Open
Abstract
The photoactive Orange Carotenoid Protein (OCP) plays a key role in cyanobacterial photoprotection. In OCP, a single non-covalently bound keto-carotenoid molecule acts as a light intensity sensor, while the protein is responsible for forming molecular contacts with the light-harvesting antenna, the fluorescence of which is quenched by OCP. Activation of this physiological interaction requires signal transduction from the photoexcited carotenoid to the protein matrix. Recent works revealed an asynchrony between conformational transitions of the carotenoid and the protein. Intrinsic tryptophan (Trp) fluorescence has provided valuable information about the protein part of OCP during its photocycle. However, wild-type OCP contains five Trp residues, which makes extraction of site-specific information impossible. In this work, we overcame this problem by characterizing the photocycle of a fully photoactive OCP variant (OCP-3FH) with only the most critical tryptophan residue (Trp-288) in place. Trp-288 is of special interest because it forms a hydrogen bond to the carotenoid's keto-oxygen to keep OCP in its dark-adapted state. Using femtosecond pump-probe fluorescence spectroscopy we analyzed the photocycle of OCP-3FH and determined the formation rate of the very first intermediate suggesting that generation of the recently discovered S* state of the carotenoid in OCP precedes the breakage of the hydrogen bonds. Therefore, following Trp fluorescence of the unique photoactive OCP-3FH variant, we identified the rate of the H-bond breakage and provided novel insights into early events accompanying photoactivation of wild-type OCP.
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Affiliation(s)
- Eugene G. Maksimov
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia ,0000 0004 0468 2555grid.425156.1A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Elena A. Protasova
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Georgy V. Tsoraev
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor A. Yaroshevich
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Anton I. Maydykovskiy
- 0000 0001 2342 9668grid.14476.30Department of Quantum Electronics, Faculty of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Evgeny A. Shirshin
- 0000 0001 2342 9668grid.14476.30Department of Quantum Electronics, Faculty of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Timofey S. Gostev
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | | | - Marcus Moldenhauer
- 0000 0001 2292 8254grid.6734.6Technical University of Berlin, Institute of Chemistry PC 14, Straße des des 17. Juni 135, 10623 Berlin, Germany
| | - Yury B. Slonimskiy
- 0000 0004 0468 2555grid.425156.1A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Nikolai N. Sluchanko
- 0000 0001 2342 9668grid.14476.30Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia ,0000 0004 0468 2555grid.425156.1A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Thomas Friedrich
- 0000 0001 2292 8254grid.6734.6Technical University of Berlin, Institute of Chemistry PC 14, Straße des des 17. Juni 135, 10623 Berlin, Germany
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17
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Roskamp KW, Azim S, Kassier G, Norton-Baker B, Sprague-Piercy MA, Miller RJD, Martin RW. Human γS-Crystallin-Copper Binding Helps Buffer against Aggregation Caused by Oxidative Damage. Biochemistry 2020; 59:2371-2385. [PMID: 32510933 DOI: 10.1021/acs.biochem.0c00293] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Divalent metal cations can play a role in protein aggregation diseases, including cataract. Here we compare the aggregation of human γS-crystallin, a key structural protein of the eye lens, via mutagenesis, ultraviolet light damage, and the addition of metal ions. All three aggregation pathways result in globular, amorphous-looking structures that do not elongate into fibers. We also investigate the molecular mechanism underlying copper(II)-induced aggregation. This work was motivated by the observation that zinc(II)-induced aggregation of γS-crystallin is driven by intermolecular bridging of solvent-accessible cysteine residues, while in contrast, copper(II)-induced aggregation of this protein is exacerbated by the removal of solvent-accessible cysteines via mutation. Here we find that copper(II)-induced aggregation results from a complex mechanism involving multiple interactions with the protein. The initial protein-metal interactions result in the reduction of Cu(II) to Cu(I) with concomitant oxidation of γS-crystallin. In addition to the intermolecular disulfides that represent a starting point for aggregation, intramolecular disulfides also occur in the cysteine loop, a region of the N-terminal domain that was previously found to mediate the early stages of cataract formation. This previously unobserved ability of γS-crystallin to transfer disulfides intramolecularly suggests that it may serve as an oxidation sink for the lens after glutathione levels have become depleted during aging. γS-Crystallin thus serves as the last line of defense against oxidation in the eye lens, a result that underscores the chemical functionality of this protein, which is generally considered to play a purely structural role.
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Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Sana Azim
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Günther Kassier
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Brenna Norton-Baker
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States.,Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Marc A Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - R J Dwyane Miller
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, Hamburg 22761, Germany.,Departments of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Rachel W Martin
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
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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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Rana S, Sarmah S, Singha Roy A, Ghosh KS. Elucidation of molecular interactions between human γD-crystallin and quercetin, an inhibitor against tryptophan oxidation. J Biomol Struct Dyn 2020; 39:1811-1818. [DOI: 10.1080/07391102.2020.1738960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh, India
| | - Sharat Sarmah
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong, India
| | - Atanu Singha Roy
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh, India
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20
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Rana S, Ghosh KS. Explication of human γD-crystallin interactions with its aggregation inhibitor Schiff base at molecular level. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Aguayo-Ortiz R, Dominguez L. Effects of Mutating Trp42 Residue on γD-Crystallin Stability. J Chem Inf Model 2020; 60:777-785. [PMID: 31747273 DOI: 10.1021/acs.jcim.9b00747] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Oligomerization and aggregation of γD-crystallins (HγDC) in the eye lens is one of the main causes of cataract development. To date, several congenital mutations related to this protein are known to promote the formation of aggregates. Previous studies have demonstrated that mutations in W42 residue of HγDC lead to the generation of partially unfolded intermediates that are more prone to aggregate. To understand the role of W42 in the stability of HγDC, we performed alchemical free-energy calculations and all-atom molecular dynamics simulations of different W42 mutant models. Our results suggest that substitution of W42 by small size and/or polar residues promotes HγDC denaturation due to the entry of water molecules into the hydrophobic core of the N-terminal domain. Similar behavior was observed in the C-terminal domain of HγDC when mutating the W130 residue located in a homologous position. Moreover, the exposure of the hydrophobic core residues could lead to the formation of aggregation-prone partially unfolded species. Overall, this study takes a step toward understanding the role of HγDC in cataract development.
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Affiliation(s)
- Rodrigo Aguayo-Ortiz
- Facultad de Química, Departamento de Fisicoquímica , Universidad Nacional Autónoma de México , Mexico City 04510 , Mexico.,Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Laura Dominguez
- Facultad de Química, Departamento de Fisicoquímica , Universidad Nacional Autónoma de México , Mexico City 04510 , Mexico
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22
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Rana S, Ghosh KS. Protective role of hesperetin against posttranslational oxidation of tryptophan residue of human γD-crystallin: A molecular level study. Arch Biochem Biophys 2019; 679:108204. [PMID: 31758928 DOI: 10.1016/j.abb.2019.108204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/30/2019] [Accepted: 11/19/2019] [Indexed: 11/19/2022]
Abstract
Crystallin proteins undergo various posttranslational modifications with aging of eye lens. Oxidation of tryptophan (Trp) residues of a major γ-crystallin namely human γD-crystallin (HGD) was found to be inhibited by a naturally occurring flavonoid hesperetin at relatively low concentration mostly due to its antioxidant activity. Further the molecular interactions between HGD and hesperetin were elucidated on the basis of the quenching of Trp fluorescence of the protein by the flavonoid. Ground state complexation between HGD and hesperetin caused static quenching of the Trp fluorescence of HGD. Binding and quenching constants were in the order of (103- 104 M-1). Energy transfer from protein to hesperetin was suggested by FRET calculations. Thermodynamic parameters reveal significant hydrophobic association between the protein and hesperetin. Synchronous fluorescence and CD spectroscopic results had ruled out conformational changes in the protein due to binding of hesperetin. Docking studies suggested the proximity of hesperetin with Trp 42, which largely corroborates our experimental findings.
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Affiliation(s)
- 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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23
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Rana S, Velappan AB, Debnath J, Ghosh KS. Inhibition of copper-induced aggregation of human γD-crystallin by a diimine molecule and investigations on their molecular interactions. J Biomol Struct Dyn 2019; 38:4914-4920. [DOI: 10.1080/07391102.2019.1686426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh, India
| | - Anand Babu Velappan
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA University, Thanjavur, Tamil Nadu, India
| | - Joy Debnath
- Department of Chemistry, School of Chemical and Biotechnology, SASTRA University, Thanjavur, Tamil Nadu, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh, India
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24
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Mills-Henry IA, Thol SL, Kosinski-Collins MS, Serebryany E, King JA. Kinetic Stability of Long-Lived Human Lens γ-Crystallins and Their Isolated Double Greek Key Domains. Biophys J 2019; 117:269-280. [PMID: 31266635 DOI: 10.1016/j.bpj.2019.06.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 05/25/2019] [Accepted: 06/05/2019] [Indexed: 12/17/2022] Open
Abstract
The γ-crystallins of the eye lens nucleus are among the longest-lived proteins in the human body. Synthesized in utero, they must remain folded and soluble throughout adulthood to maintain lens transparency and avoid cataracts. γD- and γS-crystallin are two major monomeric crystallins of the human lens. γD-crystallin is concentrated in the oldest lens fiber cells, the lens nucleus, whereas γS-crystallin is concentrated in the younger cells of the lens cortex. The kinetic stability parameters of these two-domain proteins and their isolated domains were determined and compared. Kinetic unfolding experiments monitored by fluorescence spectroscopy in varying concentrations of guanidinium chloride were used to extrapolate unfolding rate constants and half-lives of the crystallins in the absence of the denaturant. Consistent with their long lifespans in the lens, extrapolated half-lives for the initial unfolding step were on the timescale of years. Both proteins' isolated N-terminal domains were less kinetically stable than their respective C-terminal domains at denaturant concentrations predicted to disrupt the domain interface, but at low denaturant concentrations, the relative kinetic stabilities were reversed. Cataract-associated aggregation has been shown to proceed from partially unfolded intermediates in these proteins; their extreme kinetic stability likely evolved to protect the lens from the initiation of aggregation reactions. Our findings indicate that the domain interface is the source of significant kinetic stability. The gene duplication and fusion event that produced the modern two-domain architecture of vertebrate lens crystallins may be the origin of their high kinetic as well as thermodynamic stability.
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Affiliation(s)
- Ishara A Mills-Henry
- Department of Chemistry and Food Science, Framingham State University, Framingham, Massachusetts
| | | | | | - Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts.
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
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25
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Bari KJ, Sharma S, Chary KVR. Structural and functional characterization of a missense mutant of human γS-crystallin associated with dominant infantile cataracts. Biochem Biophys Res Commun 2018; 506:862-867. [PMID: 30391002 DOI: 10.1016/j.bbrc.2018.10.187] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 10/29/2018] [Indexed: 01/19/2023]
Abstract
Infantile cataracts constitute one of the most important causes of childhood blindness worldwide. Human γS-crystallin is the most abundant protein in the eye lens cortex. A missense mutant of human γS-crystallin, Y67N (abbreviated hereafter as γS-Y67N) is recently reported to be associated with dominant infantile cataracts. To understand the structural basis for γS-Y67N to cause lens opacification, we constructed, expressed and purified γS-Y67N and its wild-type (abbreviated hereafter as γS-WT) and studied the structural and functional differences between them in solution using circular dichroism (CD), differential scanning calorimetry (DSC), fluorescence spectroscopy and extrinsic spectral probes. Extensive equilibrium characterization indicate that replacement of the highly conserved Tyr at 67th position by Asn distorts the conserved Tyr corner at the second Greek key motif in the N-terminal domain (NTD) and leads to substantial loss of structural stability. Our intrinsic fluorescence quenching results reveal differential in-vitro refolding kinetics identifying partially folded kinetic intermediates for both proteins. Extrinsic fluorescence studies further reveal loosening up of the compact structure of γS-crystallin upon mutation associated with enhanced aggregation. As Ca2+ homeostasis is a crucial regulator of lens transparency, we further investigated the Ca2+-binding properties of γS-WT and γS-Y67N by isothermal titration calorimetry (ITC) to identify lens Ca2+ distribution in health and in disease. Overall, our results highlight the vital role of conserved Tyr corners in stabilizing Greek key motifs and provide useful structural and functional insights into the mechanism of cataract formation in humans.
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Affiliation(s)
- Khandekar Jishan Bari
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad, 500107, India
| | - Shrikant Sharma
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad, 500107, India
| | - Kandala V R Chary
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad, 500107, India; Department of Chemical Sciences, Tata Institute of Fundamental Research, 1, Homi Bhabha Road, Colaba, Mumbai, 400005, India; Indian Institute of Science Education and Research, Berhampur, Odisha, 760010, India.
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26
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Zhu S, Xi XB, Duan TL, Zhai Y, Li J, Yan YB, Yao K. The cataract-causing mutation G75V promotes γS-crystallin aggregation by modifying and destabilizing the native structure. Int J Biol Macromol 2018; 117:807-814. [DOI: 10.1016/j.ijbiomac.2018.05.220] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/25/2018] [Accepted: 05/29/2018] [Indexed: 12/31/2022]
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27
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Xu J, Zhao WJ, Chen XJ, Yao K, Yan YB. Introduction of an extra tryptophan fluorophore by cataract-associating mutations destabilizes βB2-crystallin and promotes aggregation. Biochem Biophys Res Commun 2018; 504:851-856. [DOI: 10.1016/j.bbrc.2018.09.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 09/06/2018] [Indexed: 12/18/2022]
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28
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Zhao WJ, Yan YB. Increasing susceptibility to oxidative stress by cataract-causing crystallin mutations. Int J Biol Macromol 2018; 108:665-673. [DOI: 10.1016/j.ijbiomac.2017.12.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 12/01/2017] [Accepted: 12/04/2017] [Indexed: 11/24/2022]
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29
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Zhao WJ, Xu J, Chen XJ, Liu HH, Yao K, Yan YB. Effects of cataract-causing mutations W59C and W151C on βB2-crystallin structure, stability and folding. Int J Biol Macromol 2017; 103:764-770. [DOI: 10.1016/j.ijbiomac.2017.05.109] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 10/19/2022]
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30
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Chaudhury S, Bag S, Bose M, Das AK, Ghosh AK, Dasgupta S. Protection of human γB-crystallin from UV-induced damage by epigallocatechin gallate: spectroscopic and docking studies. MOLECULAR BIOSYSTEMS 2017; 12:2901-9. [PMID: 27410057 DOI: 10.1039/c6mb00256k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The transparency of the human eye lens depends on the solubility and stability of the structural proteins of the eye lens, the crystallins. Although the mechanism of cataract formation is still unclear, it is believed to involve protein misfolding and/or aggregation of proteins due to the influence of several external factors such as ultraviolet (UV) radiation, low pH, temperature and exposure to chemical agents. In this article, we report the study of UV induced photo-damage (under oxidative stress) of recombinant human γB-crystallin in vitro in the presence of the major green tea polyphenol, (-)-epigallocatechin gallate (EGCG). We have shown that EGCG has the ability to protect human γB-crystallin from oxidative stress-induced photo-damage.
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Affiliation(s)
| | - Sudipta Bag
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - Madhuparna Bose
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ananta Kumar Ghosh
- Department of Biotechnology, 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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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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32
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Cetinel S, Semenchenko V, Cho JY, Sharaf MG, Damji KF, Unsworth LD, Montemagno C. UV-B induced fibrillization of crystallin protein mixtures. PLoS One 2017; 12:e0177991. [PMID: 28542382 PMCID: PMC5444657 DOI: 10.1371/journal.pone.0177991] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 05/05/2017] [Indexed: 12/28/2022] Open
Abstract
Environmental factors, mainly oxidative stress and exposure to sunlight, induce the oxidation, cross-linking, cleavage, and deamination of crystallin proteins, resulting in their aggregation and, ultimately, cataract formation. Various denaturants have been used to initiate the aggregation of crystallin proteins in vitro. All of these regimens, however, are obviously far from replicating conditions that exist in vivo that lead to cataract formation. In fact, it is our supposition that only UV-B radiation may mimic the observed in vivo cause of crystallin alteration leading to cataract formation. This means of inducing cataract formation may provide the most appropriate in vitro platform for in-depth study of the fundamental cataractous fibril properties and allow for testing of possible treatment strategies. Herein, we showed that cataractous fibrils can be formed using UV-B radiation from α:β:γ crystallin protein mixtures. Characterization of the properties of formed aggregates confirmed the development of amyloid-like fibrils, which are in cross-β-pattern and possibly in anti-parallel β-sheet arrangement. Furthermore, we were also able to confirm that the presence of the molecular chaperone, α-crystallin, was able to inhibit fibril formation, as observed for ‘naturally’ occurring fibrils. Finally, the time-dependent fibrillation profile was found to be similar to the gradual formation of age-related nuclear cataracts. This data provided evidence for the initiation of fibril formation from physiologically relevant crystallin mixtures using UV-B radiation, and that the formed fibrils had several traits similar to that expected from cataracts developing in vivo.
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Affiliation(s)
- 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 (NINT), 11421, Saskatchewan Drive NW, Edmonton, AB, Canada
| | - Jae-Young Cho
- National Institute of Nanotechnology (NINT), 11421, Saskatchewan Drive NW, Edmonton, AB, Canada
| | - Mehdi Ghaffari Sharaf
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
- Ingenuity Lab., University of Alberta, 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 (NINT), 11421, Saskatchewan Drive NW, Edmonton, AB, Canada
- * E-mail: (CM); (LDU)
| | - Carlo Montemagno
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
- Ingenuity Lab., University of Alberta, Edmonton, AB, Canada
- * E-mail: (CM); (LDU)
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33
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Patterson RE, Weatherbee-Martin N, Rainey JK. Pyrene-Apelin Conjugation Modulates Fluorophore- and Peptide-Micelle Interactions. J Phys Chem B 2017; 121:4768-4777. [PMID: 28414462 DOI: 10.1021/acs.jpcb.7b02376] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bioactive apelin peptide forms ranging in length from 12 to 55 amino acids bind to and activate the apelin receptor (AR or APJ), a class A G-protein coupled receptor. Apelin-12, -17, and -36 isoforms, named according to length, with an additional N-terminal cysteine residue allowed for regiospecific and efficient conjugation of pyrene maleimide. Through steady-state fluorescence spectroscopy, the emission properties of pyrene in aqueous buffer were compared to those of the pyrene-apelin conjugates both without and with zwitterionic or anionic micelles. Pyrene photophysics are consistent with an expected partitioning into the hydrophobic micellar cores, while pyrene-apelin conjugation prevented this partitioning. Apelin, conversely, is expected to preferentially interact with anionic micelles; pyrene-apelin conjugates appear to lose preferential interaction. Finally, Förster resonance energy transfer between pyrene and tryptophan residues in the N-terminal tail and first transmembrane segment (the AR55 construct, comprising residues 1-55 of the AR) was consistent with efficient nonspecific pyrene-apelin conjugate binding to micelles rather than direct, specific apelin-AR55 binding. This approach provides a versatile fluorophore conjugation strategy for apelin, particularly valuable given that even a highly hydrophobic fluorophore is not deleterious to peptide behavior in membrane-mimetic micellar systems.
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Affiliation(s)
- Robin E Patterson
- Departments of †Biochemistry & Molecular Biology and ‡Chemistry, Dalhousie University , Halifax, Nova Scotia B3H 4R2, Canada
| | - Nathan Weatherbee-Martin
- Departments of †Biochemistry & Molecular Biology and ‡Chemistry, Dalhousie University , Halifax, Nova Scotia B3H 4R2, Canada
| | - Jan K Rainey
- Departments of †Biochemistry & Molecular Biology and ‡Chemistry, Dalhousie University , Halifax, Nova Scotia B3H 4R2, Canada
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Qi LB, Hu LD, Liu H, Li HY, Leng XY, Yan YB. Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain. Protein Cell 2016; 7:501-15. [PMID: 27318838 PMCID: PMC4930773 DOI: 10.1007/s13238-016-0284-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 05/04/2016] [Indexed: 01/02/2023] Open
Abstract
β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying cataract caused by most mutations remains uncharacterized. The S228P mutation in βB1-crystallin has been linked to autosomal dominant congenital nuclear cataract. Here we found that the S228P mutant was prone to aggregate and degrade in both of the human and E. coli cells. The intracellular S228P aggregates could be redissolved by lanosterol. The S228P mutation modified the refolding pathway of βB1-crystallin by affecting the formation of the dimeric intermediate but not the monomeric intermediate. Compared with native βB1-crystallin, the refolded S228P protein had less packed structures, unquenched Trp fluorophores and increased hydrophobic exposure. The refolded S228P protein was prone to aggregate at the physiological temperature and decreased the protective effect of βB1-crystallin on βA3-crystallin. Molecular dynamic simulation studies indicated that the mutation decreased the subunit binding energy and modified the distribution of surface electrostatic potentials. More importantly, the mutation separated two interacting loops in the C-terminal domain, which shielded the hydrophobic core from solvent in native βB1-crystallin. These two interacting loops are highly conserved in both of the N- and C-terminal domains of all β/γ-crystallins. We propose that these two interacting loops play an important role in the folding and structural stability of β/γ-crystallin domains by protecting the hydrophobic core from solvent access.
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Affiliation(s)
- Liang-Bo Qi
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Li-Dan Hu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Huihui Liu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Hai-Yun Li
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xiao-Yao Leng
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yong-Bin Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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35
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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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Abstract
It was recently demonstrated that in ferric myoglobins (Mb) the fluorescence quenching of the photoexcited tryptophan 14 (*Trp(14)) residue is in part due to an electron transfer to the heme porphyrin (porph), turning it to the ferrous state. However, the invariance of *Trp decay times in ferric and ferrous Mbs raises the question as to whether electron transfer may also be operative in the latter. Using UV pump/visible probe transient absorption, we show that this is indeed the case for deoxy-Mb. We observe that the reduction generates (with a yield of about 30%) a low-valence Fe-porphyrin π [Fe(II)(porph(●-))] -anion radical, which we observe for the first time to our knowledge under physiological conditions. We suggest that the pathway for the electron transfer proceeds via the leucine 69 (Leu(69)) and valine 68 (Val(68)) residues. The results on ferric Mbs and the present ones highlight the generality of Trp-porphyrin electron transfer in heme proteins.
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37
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Callis PR. Binding phenomena and fluorescence quenching. II: Photophysics of aromatic residues and dependence of fluorescence spectra on protein conformation. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.051] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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38
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Sergeeva OA, Tran MT, Haase-Pettingell C, King JA. Biochemical characterization of mutants in chaperonin proteins CCT4 and CCT5 associated with hereditary sensory neuropathy. J Biol Chem 2014; 289:27470-80. [PMID: 25124038 DOI: 10.1074/jbc.m114.576033] [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: 11/06/2022] Open
Abstract
Hereditary sensory neuropathies are a class of disorders marked by degeneration of the nerve fibers in the sensory periphery neurons. Recently, two mutations were identified in the subunits of the eukaryotic cytosolic chaperonin TRiC, a protein machine responsible for folding actin and tubulin in the cell. C450Y CCT4 was identified in a stock of Sprague-Dawley rats, whereas H147R CCT5 was found in a human Moroccan family. As with many genetically identified mutations associated with neuropathies, the underlying molecular basis of the mutants was not defined. We investigated the biochemical properties of these mutants using an expression system in Escherichia coli that produces homo-oligomeric rings of CCT4 and CCT5. Full-length versions of both mutant protein chains were expressed in E. coli at levels approaching that of the WT chains. Sucrose gradient centrifugation revealed chaperonin-sized complexes of both WT and mutant chaperonins, but with reduced recovery of C450Y CCT4 soluble subunits. Electron microscopy of negatively stained samples of C450Y CCT4 revealed few ring-shaped species, whereas WT CCT4, H147R CCT5, and WT CCT5 revealed similar ring structures. CCT5 complexes were assayed for their ability to suppress aggregation of and refold the model substrate γd-crystallin, suppress aggregation of mutant huntingtin, and refold the physiological substrate β-actin in vitro. H147R CCT5 was not as efficient in chaperoning these substrates as WT CCT5. The subtle effects of these mutations are consistent with the homozygous disease phenotype, in which most functions are carried out during development and adulthood, but some selective function is lost or reduced.
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Affiliation(s)
- Oksana A Sergeeva
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Meme T Tran
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Cameron Haase-Pettingell
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Jonathan A King
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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39
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Callis PR. Simulating electrostatic effects on electronic transitions in proteins. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.923571] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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40
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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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41
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Abstract
Principles behind quenching of tryptophan (Trp) fluorescence are updated and extended in light of recent 100-ns and 1-μs molecular dynamics (MD) trajectories augmented with quantum mechanical (QM) calculations that consider electrostatic contributions to wavelength shifts and quenching. Four studies are summarized, including (1) new insight into the single exponential decay of NATA, (2) a study revealing how unsuspected rotamer transitions affect quenching of Trp when used as a probe of protein folding, (3) advances in understanding the origin of nonexponential decay from 100-ns simulations on 19 Trps in 16 proteins, and (4) the correlation of wavelength with lifetime for decay-associated spectra (DAS). Each study strongly reinforces the concept that-for Trp-electron transfer-based quenching is controlled much more by environment electrostatic factors affecting the charge transfer (CT) state energy than by distance dependence of electronic coupling. In each case, water plays a large role in unexpected ways.
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42
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Sergeeva OA, Yang J, King JA, Knee KM. Group II archaeal chaperonin recognition of partially folded human γD-crystallin mutants. Protein Sci 2014; 23:693-702. [PMID: 24615724 DOI: 10.1002/pro.2452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/24/2014] [Accepted: 03/04/2014] [Indexed: 11/12/2022]
Abstract
The features in partially folded intermediates that allow the group II chaperonins to distinguish partially folded from native states remain unclear. The archaeal group II chaperonin from Methanococcus Mauripaludis (Mm-Cpn) assists the in vitro refolding of the well-characterized β-sheet lens protein human γD-crystallin (HγD-Crys). The domain interface and buried cores of this Greek key conformation include side chains, which might be exposed in partially folded intermediates. We sought to assess whether particular features buried in the native state, but absent from the native protein surface, might serve as recognition signals. The features tested were (a) paired aromatic side chains, (b) side chains in the interface between the duplicated domains of HγD-Crys, and (c) side chains in the buried core which result in congenital cataract when substituted. We tested the Mm-Cpn suppression of aggregation of these HγD-Crys mutants upon dilution out of denaturant. Mm-Cpn was capable of suppressing the off-pathway aggregation of the three classes of mutants indicating that the buried residues were not recognition signals. In fact, Mm-Cpn recognized the HγD-Crys mutants better than (wild-type) WT and refolded most mutant HγD-Crys to levels twice that of WT HγD-Crys. This presumably represents the increased population or longer lifetimes of the partially folded intermediates of the mutant proteins. The results suggest that Mm-Cpn does not recognize the features of HγD-Crys tested-paired aromatics, exposed domain interface, or destabilized core-but rather recognizes other features of the partially folded β-sheet conformation that are absent or inaccessible in the native state of HγD-Crys.
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Affiliation(s)
- Oksana A Sergeeva
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
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43
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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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44
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Devi K, Sarma RJ. Exploring urea–fluoride interactions in the vicinity of a tryptophan residue. RSC Adv 2014. [DOI: 10.1039/c3ra46846a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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45
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Jaworski AF, Aitken SM. Exploration of the six tryptophan residues of Escherichia coli cystathionine β-lyase as probes of enzyme conformational change. Arch Biochem Biophys 2013; 538:138-44. [DOI: 10.1016/j.abb.2013.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/06/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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46
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UV-radiation induced disruption of dry-cavities in human γD-crystallin results in decreased stability and faster unfolding. Sci Rep 2013; 3:1560. [PMID: 23532089 PMCID: PMC3609025 DOI: 10.1038/srep01560] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/11/2013] [Indexed: 11/28/2022] Open
Abstract
Age-onset cataracts are believed to be expedited by the accumulation of UV-damaged human γD-crystallins in the eye lens. Here we show with molecular dynamics simulations that the stability of γD-crystallin is greatly reduced by the conversion of tryptophan to kynurenine due to UV-radiation, consistent with previous experimental evidences. Furthermore, our atomic-detailed results reveal that kynurenine attracts more waters and other polar sidechains due to its additional amino and carbonyl groups on the damaged tryptophan sidechain, thus breaching the integrity of nearby dry center regions formed by the two Greek key motifs in each domain. The damaged tryptophan residues cause large fluctuations in the Tyr-Trp-Tyr sandwich-like hydrophobic clusters, which in turn break crucial hydrogen-bonds bridging two β-strands in the Greek key motifs at the “tyrosine corner”. Our findings may provide new insights for understanding of the molecular mechanism of the initial stages of UV-induced cataractogenesis.
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47
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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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48
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Schafheimer N, King J. Tryptophan cluster protects human γD-crystallin from ultraviolet radiation-induced photoaggregation in vitro. Photochem Photobiol 2013; 89:1106-15. [PMID: 23683003 PMCID: PMC3823069 DOI: 10.1111/php.12096] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 05/12/2013] [Indexed: 11/30/2022]
Abstract
Exposure to ultraviolet radiation (UVR) is a significant risk factor for age-related cataract, a disease of the human lens and the most prevalent cause of blindness in the world. Cataract pathology involves protein misfolding and aggregation of the primary proteins of the lens, the crystallins. Human γD-crystallin (HγD-Crys) is a major γ-crystallin in the nucleus of the human lens. We report here analysis of UVR-induced damage to HγD-Crys in vitro. Irradiation of solutions of recombinant HγD-Crys with UVA/UVB light produced a rise in solution turbidity due to polymerization of the monomeric crystallins into higher molecular weight aggregates. A significant fraction of this polymerized protein was covalently linked. Photoaggregation of HγD-Crys required oxygen and its rate was protein concentration and UVR dose dependent. To investigate the potential roles of individual tryptophan residues in photoaggregation, triple W:F mutants of HγD-Crys were irradiated. Surprisingly, despite reducing UVR absorbing capacity, multiple W:F HγD-Crys mutant proteins photoaggregated more quickly and extensively than wild type. The results reported here are consistent with previous studies that postulated that an energy transfer mechanism between the highly conserved pairs of tryptophan residues in HγD-Crys could be protective against UVR-induced photodamage.
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49
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Mahler B, Chen Y, Ford J, Thiel C, Wistow G, Wu Z. Structure and dynamics of the fish eye lens protein, γM7-crystallin. Biochemistry 2013; 52:3579-87. [PMID: 23597261 DOI: 10.1021/bi400151c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The vertebrate eye lens contains high concentrations of crystallins. The dense lenses of fish are particularly abundant in a class called γM-crystallin whose members are characterized by an unusually high methionine content and partial loss of the four tryptophan residues conserved in all γ-crystallins from mammals which are proposed to contribute to protection from UV-damage. Here, we present the structure and dynamics of γM7-crystallin from zebrafish (Danio rerio). The solution structure shares the typical two-domain, four-Greek-key motif arrangement of other γ-crystallins, with the major difference noted in the final loop of the N-terminal domain, spanning residues 65-72. This is likely due to the absence of the conserved tryptophans. Many of the methionine residues are exposed on the surface but are mostly well-ordered and frequently have contacts with aromatic side chains. This may contribute to the specialized surface properties of these proteins that exist under high molecular crowding in the fish lens. NMR relaxation data show increased backbone conformational motions in the loop regions of γM7 compared to those of mouse γS-crystallin and show that fast internal motion of the interdomain linker in γ-crystallins correlates with linker length. Unfolding studies monitored by tryptophan fluorescence confirm results from mutant mouse γS-crystallin and show that unfolding of a βγ-crystallin domain likely starts from unfolding of the variable loop containing the more fluorescently quenched tryptophan residue, resulting in a native-like unfolding intermediate.
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Affiliation(s)
- Bryon Mahler
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Yingwei Chen
- Section on Molecular Structure and Function, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jason Ford
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Caleb Thiel
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Graeme Wistow
- Section on Molecular Structure and Function, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Zhengrong Wu
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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Ji F, Jung J, Koharudin LMI, Gronenborn AM. The human W42R γD-crystallin mutant structure provides a link between congenital and age-related cataracts. J Biol Chem 2012; 288:99-109. [PMID: 23124202 DOI: 10.1074/jbc.m112.416354] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Some mutants of human γD-crystallin are closely linked to congenital cataracts, although the detailed molecular mechanisms of mutant-associated cataract formation are generally not known. Here we report on a recently discovered γD-crystallin mutant (W42R) that has been linked to autosomal dominant, congenital cataracts in a Chinese family. The mutant protein is much less soluble and stable than wild-type γD-crystallin. We solved the crystal structure of W42R at 1.7 Å resolution, which revealed only minor differences from the wild-type structure. Interestingly, the W42R variant is highly susceptible to protease digestion, suggesting the presence of a small population of partially unfolded protein. This partially unfolded species was confirmed and quantified by NMR spectroscopy. Hydrogen/deuterium exchange experiments revealed chemical exchange between the folded and unfolded species. Exposure of wild-type γD-crystallin to UV caused damage to the N-terminal domain of the protein, resulting in very similar proteolytic susceptibility as observed for the W42R mutant. Altogether, our combined data allowed us to propose a model for W42R pathogenesis, with the W42R mutant serving as a mimic for photodamaged γD-crystallin involved in age-related cataract.
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Affiliation(s)
- Fangling Ji
- School of Life Science and Biotechnology, Dalian University of Technology, Lingong Road, Dalian 116024, China
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