1
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Serebryany E, Martin RW, Takahashi GR. The Functional Significance of High Cysteine Content in Eye Lens γ-Crystallins. Biomolecules 2024; 14:594. [PMID: 38786000 PMCID: PMC11118217 DOI: 10.3390/biom14050594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
Cataract disease is strongly associated with progressively accumulating oxidative damage to the extremely long-lived crystallin proteins of the lens. Cysteine oxidation affects crystallin folding, interactions, and light-scattering aggregation especially strongly due to the formation of disulfide bridges. Minimizing crystallin aggregation is crucial for lifelong lens transparency, so one might expect the ubiquitous lens crystallin superfamilies (α and βγ) to contain little cysteine. Yet, the Cys content of γ-crystallins is well above the average for human proteins. We review literature relevant to this longstanding puzzle and take advantage of expanding genomic databases and improved machine learning tools for protein structure prediction to investigate it further. We observe remarkably low Cys conservation in the βγ-crystallin superfamily; however, in γ-crystallin, the spatial positioning of Cys residues is clearly fine-tuned by evolution. We propose that the requirements of long-term lens transparency and high lens optical power impose competing evolutionary pressures on lens βγ-crystallins, leading to distinct adaptations: high Cys content in γ-crystallins but low in βB-crystallins. Aquatic species need more powerful lenses than terrestrial ones, which explains the high methionine content of many fish γ- (and even β-) crystallins. Finally, we discuss synergies between sulfur-containing and aromatic residues in crystallins and suggest future experimental directions.
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Affiliation(s)
- Eugene Serebryany
- Department of Physiology & Biophysics, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
- Laufer Center for Physical & Quantitative Biology, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
| | - Rachel W. Martin
- Department of Chemistry, UCI Irvine, Irvine, CA 92697-2025, USA
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
| | - Gemma R. Takahashi
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
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2
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Dziedzic A, Michlewska S, Jóźwiak P, Dębski J, Karbownik MS, Łaczmański Ł, Kujawa D, Glińska S, Miller E, Niwald M, Kloc M, Balcerzak Ł, Saluk J. Quantitative and structural changes of blood platelet cytoskeleton proteins in multiple sclerosis (MS). J Autoimmun 2024; 145:103204. [PMID: 38520895 DOI: 10.1016/j.jaut.2024.103204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/22/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
Epidemiological studies show that cardiovascular events related to platelet hyperactivity remain the leading causes of death among multiple sclerosis (MS) patients. Quantitative or structural changes of platelet cytoskeleton alter their morphology and function. Here, we demonstrated, for the first time, the structural changes in MS platelets that may be related to their hyperactivity. MS platelets were found to form large aggregates compared to control platelets. In contrast to the control, the images of overactivated, irregularly shaped MS platelets show changes in the cytoskeleton architecture, fragmented microtubule rings. Furthermore, MS platelets have long and numerous pseudopodia rich in actin filaments. We showed that MS platelets and megakaryocytes, overexpress β1-tubulin and β-actin mRNAs and proteins and have altered post-translational modification patterns. Moreover, we identified two previously undisclosed mutations in the gene encoding β1-tubulin in MS. We propose that the demonstrated structural changes of platelet cytoskeleton enhance their ability to adhere, aggregate, and degranulate fueling the risk of adverse cardiovascular events in MS.
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Affiliation(s)
- Angela Dziedzic
- University of Lodz, Faculty of Biology and Environmental Protection, Department of General Biochemistry, Pomorska 141/143, 90-236 Lodz, Poland.
| | - Sylwia Michlewska
- University of Lodz, Faculty of Biology and Environmental Protection, Laboratory of Microscopic Imaging and Specialized Biological Techniques, Banacha 12/16, 90-237, Lodz, Poland
| | - Piotr Jóźwiak
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Invertebrate Zoology and Hydrobiology, Banacha 12/16, 90-236 Lodz, Poland
| | - Janusz Dębski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a 02-106, Warsaw, Poland
| | | | - Łukasz Łaczmański
- Laboratory of Genomics & Bioinformatics, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Dorota Kujawa
- Laboratory of Genomics & Bioinformatics, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Sława Glińska
- University of Lodz, Faculty of Biology and Environmental Protection, Laboratory of Microscopic Imaging and Specialized Biological Techniques, Banacha 12/16, 90-237, Lodz, Poland
| | - Elżbieta Miller
- Department of Neurological Rehabilitation, Medical University of Lodz, Milionowa 14, 93-113 Lodz, Poland
| | - Marta Niwald
- Department of Neurological Rehabilitation, Medical University of Lodz, Milionowa 14, 93-113 Lodz, Poland
| | - Malgorzata Kloc
- The Houston Methodist Research Institute, Houston, TX 77030, USA; Department of Surgery, The Houston Methodist Hospital, Houston, TX 77030, USA; M.D. Anderson Cancer Center, Department of Genetics, The University of Texas, Houston, TX 77030, USA
| | - Łucja Balcerzak
- University of Lodz, Faculty of Biology and Environmental Protection, Laboratory of Microscopic Imaging and Specialized Biological Techniques, Banacha 12/16, 90-237, Lodz, Poland
| | - Joanna Saluk
- University of Lodz, Faculty of Biology and Environmental Protection, Department of General Biochemistry, Pomorska 141/143, 90-236 Lodz, Poland
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3
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Rolland AD, Takata T, Donor MT, Lampi KJ, Prell JS. Eye lens β-crystallins are predicted by native ion mobility-mass spectrometry and computations to form compact higher-ordered heterooligomers. Structure 2023; 31:1052-1064.e3. [PMID: 37453416 PMCID: PMC10528727 DOI: 10.1016/j.str.2023.06.013] [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: 10/24/2022] [Revised: 05/04/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023]
Abstract
Eye lens α- and β-/γ-crystallin proteins are not replaced after fiber cell denucleation and maintain lens transparency and refractive properties. The exceptionally high (∼400-500 mg/mL) concentration of crystallins in mature lens tissue and multiple other factors impede precise characterization of β-crystallin interactions, oligomer composition, size, and topology. Native ion mobility-mass spectrometry is used here to probe β-crystallin association and provide insight into homo- and heterooligomerization kinetics for these proteins. These experiments include separation and characterization of higher-order β-crystallin oligomers and illustrate the unique advantages of native IM-MS. Recombinantly expressed βB1, βB2, and βA3 isoforms are found to have different homodimerization propensities, and only βA3 forms larger homooligomers. Heterodimerization of βB2 with βA3 occurs ∼3 times as fast as that of βB1 with βA3, and βB1 and βB2 heterodimerize less readily. Ion mobility experiments, molecular dynamics simulations, and PISA analysis together reveal that observed oligomers are consistent with predominantly compact, ring-like topologies.
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Affiliation(s)
- Amber D Rolland
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA
| | - Takumi Takata
- Kyoto University, Research Reactor Institute 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Micah T Donor
- Department of Biological & Molecular Sciences, George Fox University, 414 N Meridian St, Newberg, OR 97132, USA
| | - Kirsten J Lampi
- Integrative Biosciences, School of Dentistry, 3181 SW Sam Jackson Park Road, Oregon Health & Science University, Portland, OR 97239-3098, USA.
| | - James S Prell
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA; Materials Science Institute, 1252 University of Oregon, Eugene, OR 97403-1252, USA.
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4
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Deamidation of the human eye lens protein γS-crystallin accelerates oxidative aging. Structure 2022; 30:763-776.e4. [PMID: 35338852 PMCID: PMC9081212 DOI: 10.1016/j.str.2022.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 12/14/2021] [Accepted: 03/01/2022] [Indexed: 11/23/2022]
Abstract
Cataract, a clouding of the eye lens from protein precipitation, affects millions of people every year. The lens proteins, the crystallins, show extensive post-translational modifications (PTMs) in cataractous lenses. The most common PTMs, deamidation and oxidation, promote crystallin aggregation; however, it is not clear precisely how these PTMs contribute to crystallin insolubilization. Here, we report six crystal structures of the lens protein γS-crystallin (γS): one of the wild-type and five of deamidated γS variants, from three to nine deamidation sites, after sample aging. The deamidation mutations do not change the overall fold of γS; however, increasing deamidation leads to accelerated disulfide-bond formation. Addition of deamidated sites progressively destabilized protein structure, and the deamidated variants display an increased propensity for aggregation. These results suggest that the deamidated variants are useful as models for accelerated aging; the structural changes observed provide support for redox activity of γS-crystallin in the lens.
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5
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Saei AA, Beusch CM, Sabatier P, Wells JA, Gharibi H, Meng Z, Chernobrovkin A, Rodin S, Näreoja K, Thorsell AG, Karlberg T, Cheng Q, Lundström SL, Gaetani M, Végvári Á, Arnér ESJ, Schüler H, Zubarev RA. System-wide identification and prioritization of enzyme substrates by thermal analysis. Nat Commun 2021; 12:1296. [PMID: 33637753 PMCID: PMC7910609 DOI: 10.1038/s41467-021-21540-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 01/26/2021] [Indexed: 02/06/2023] Open
Abstract
Despite the immense importance of enzyme-substrate reactions, there is a lack of general and unbiased tools for identifying and prioritizing substrate proteins that are modified by the enzyme on the structural level. Here we describe a high-throughput unbiased proteomics method called System-wide Identification and prioritization of Enzyme Substrates by Thermal Analysis (SIESTA). The approach assumes that the enzymatic post-translational modification of substrate proteins is likely to change their thermal stability. In our proof-of-concept studies, SIESTA successfully identifies several known and novel substrate candidates for selenoprotein thioredoxin reductase 1, protein kinase B (AKT1) and poly-(ADP-ribose) polymerase-10 systems. Wider application of SIESTA can enhance our understanding of the role of enzymes in homeostasis and disease, opening opportunities to investigate the effect of post-translational modifications on signal transduction and facilitate drug discovery.
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Affiliation(s)
- Amir Ata Saei
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
| | - Christian M Beusch
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Pierre Sabatier
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Juan Astorga Wells
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Hassan Gharibi
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Zhaowei Meng
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Alexey Chernobrovkin
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Pelago Bioscience AB, Solna, Sweden
| | - Sergey Rodin
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Katja Näreoja
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Ann-Gerd Thorsell
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Tobias Karlberg
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Qing Cheng
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Susanna L Lundström
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Massimiliano Gaetani
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- SciLifeLab, Stockholm, Sweden
- Chemical Proteomics Core Facility, Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ákos Végvári
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- Proteomics Biomedicum, Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Elias S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Herwig Schüler
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Roman A Zubarev
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
- Department of Pharmacological & Technological Chemistry, I.M. Sechenov First Moscow State Medical University, Moscow, Russia.
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6
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Vetter CJ, Thorn DC, Wheeler SG, Mundorff CC, Halverson KA, Wales TE, Shinde UP, Engen JR, David LL, Carver JA, Lampi KJ. Cumulative deamidations of the major lens protein γS-crystallin increase its aggregation during unfolding and oxidation. Protein Sci 2020; 29:1945-1963. [PMID: 32697405 PMCID: PMC7454558 DOI: 10.1002/pro.3915] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 07/12/2020] [Accepted: 07/20/2020] [Indexed: 01/07/2023]
Abstract
Age-related lens cataract is the major cause of blindness worldwide. The mechanisms whereby crystallins, the predominant lens proteins, assemble into large aggregates that scatter light within the lens, and cause cataract, are poorly understood. Due to the lack of protein turnover in the lens, crystallins are long-lived. A major crystallin, γS, is heavily modified by deamidation, in particular at surface-exposed N14, N76, and N143 to introduce negative charges. In this present study, deamidated γS was mimicked by mutation with aspartate at these sites and the effect on biophysical properties of γS was assessed via dynamic light scattering, chemical and thermal denaturation, hydrogen-deuterium exchange, and susceptibility to disulfide cross-linking. Compared with wild type γS, a small population of each deamidated mutant aggregated rapidly into large, light-scattering species that contributed significantly to the total scattering. Under partially denaturing conditions in guanidine hydrochloride or elevated temperature, deamidation led to more rapid unfolding and aggregation and increased susceptibility to oxidation. The triple mutant was further destabilized, suggesting that the effects of deamidation were cumulative. Molecular dynamics simulations predicted that deamidation augments the conformational dynamics of γS. We suggest that these perturbations disrupt the native disulfide arrangement of γS and promote the formation of disulfide-linked aggregates. The lens-specific chaperone αA-crystallin was poor at preventing the aggregation of the triple mutant. It is concluded that surface deamidations cause minimal structural disruption individually, but cumulatively they progressively destabilize γS-crystallin leading to unfolding and aggregation, as occurs in aged and cataractous lenses.
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Affiliation(s)
- Calvin J. Vetter
- Integrative BiosciencesOregon Health & Science UniversityPortlandOregonUSA
| | - David C. Thorn
- Research School of Chemistry, College of ScienceThe Australian National UniversityActonAustralia
| | - Samuel G. Wheeler
- Integrative BiosciencesOregon Health & Science UniversityPortlandOregonUSA
| | - Charlie C. Mundorff
- Chemical Physiology & BiochemistryOregon Health & Science UniversityPortlandOregonUSA
- Department of Chemistry & Chemical BiologyNortheastern UniversityBostonMassachusettsUSA
| | - Kate A. Halverson
- Chemical Physiology & BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| | - Thomas E. Wales
- Department of Chemistry & Chemical BiologyNortheastern UniversityBostonMassachusettsUSA
| | - Ujwal P. Shinde
- Chemical Physiology & BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| | - John R. Engen
- Department of Chemistry & Chemical BiologyNortheastern UniversityBostonMassachusettsUSA
| | - Larry L. David
- Chemical Physiology & BiochemistryOregon Health & Science UniversityPortlandOregonUSA
| | - John A. Carver
- Research School of Chemistry, College of ScienceThe Australian National UniversityActonAustralia
| | - Kirsten J. Lampi
- Integrative BiosciencesOregon Health & Science UniversityPortlandOregonUSA
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7
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Fujii N, Takata T, Kim I, Morishima K, Inoue R, Magami K, Matsubara T, Sugiyama M, Koide T. Asp isomerization increases aggregation of α-crystallin and decreases its chaperone activity in human lens of various ages. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140446. [PMID: 32442520 DOI: 10.1016/j.bbapap.2020.140446] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/12/2020] [Accepted: 05/14/2020] [Indexed: 10/24/2022]
Abstract
α-Crystallin, comprising 40-50 subunits of αA- and αB-subunits, is a long-lived major soluble chaperone protein in lens. During aging, α-crystallin forms aggregates of high molecular weight (HMW) protein and eventually becomes water-insoluble (WI). Isomerization of Asp in α-crystallin has been proposed as a trigger of protein aggregation, ultimately leading to cataract formation. Here, we have investigated the relationship between protein aggregation and Asp isomerization of αA-crystallin by a series of analyses of the soluble α-crystallin, HMW and WI fractions from human lens samples of different ages (10-76 years). Analytical ultracentrifugation showed that the HMW fraction had a peak sedimentation coefficient of 40 S and a wide distribution of values (10-450 S) for lens of all ages, whereas the α-crystallin had a much smaller peak sedimentation coefficient (10-20 S) and was less heterogeneous, regardless of lens age. Measurement of the ratio of isomers (Lα-, Lβ-, Dα-, Dβ-) at Asp58, Asp91/92 and Asp151 in αA-crystallin by liquid chromatography-mass spectrometry showed that the proportion of isomers at all three sites increased in order of aggregation level (α-crystallin < HMW < WI fractions). Among the abnormal isomers of Asp58 and Asp151, Dβ-isomers were predominant with a very few exceptions. Notably, the chaperone activity of HMW protein was minimal for lens of all ages, whereas that of α-crystallin decreased with increasing lens age. Thus, abnormal aggregation caused by Asp isomerization might contribute to the loss of chaperone activity of α-crystallin in aged human lens.
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Affiliation(s)
- Noriko Fujii
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan.
| | - Takumi Takata
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Ingu Kim
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Ken Morishima
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Rintaro Inoue
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Kousuke Magami
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | | | - Masaaki Sugiyama
- Institute for Integrated Radiation and Nuclear Science, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Tamaki Koide
- Rexxam Co., Ltd., Nishi-ku, Nagoya, Aichi 541-0054, Japan
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8
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Takata T, Ha S, Koide T, Fujii N. Site-specific rapid deamidation and isomerization in human lens αA-crystallin in vitro. Protein Sci 2020; 29:955-965. [PMID: 31930615 PMCID: PMC7096717 DOI: 10.1002/pro.3821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/27/2019] [Accepted: 12/27/2019] [Indexed: 12/16/2022]
Abstract
Recent studies have suggested that the isomerization/racemization of aspartate residues in proteins increases in aged tissues. One such residue is Asp151 in lens-specific αA-crystallin. Although many isomerization/racemization sites have been reported in various proteins, the factors that lead to those modifications in proteins in vivo remain obscure. Therefore, an in vitro system is needed to assess the mechanisms of modifications of Asp under various conditions. Deamidation of Asn to Asp in proteins occurs more rapidly than isomerization/racemization of Asp, although the reaction passes through the same intermediate in both pathways. Here, therefore, we replaced Asp151 in human lens αA-crystallin with Asn by using site-directed mutagenesis. The recombinant protein was expressed in Escherichia coli and used to investigate the deamidation/isomerization/racemization of Asn151 after incubation at 50°C for various durations and under different pH. After incubation, the mutant αA-crystallin was subjected to enzymatic digestion followed by liquid chromatography-MS/MS to evaluate the ratio of modifications in Asn151-containing peptides. The Asp151Asn αA-crystallin mutant showed rapid deamidation to Asp with the formation of specific Asp isomers. In particular, deamidation increased greatly under basic conditions. By contrast, subunit-subunit interactions between αA-crystallin and αB-crystallin had little effect on the modification of Asn151. Our findings suggest that the Asp151Asn αA-crystallin mutant represents a good in vitro model protein to assess deamidation, isomerization, and the racemization intermediates. Furthermore, our in vitro results show a different trend from in vivo data, implying the presence of specific factors that induce racemization from L-Asp to D-Asp residues in vivo.
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Affiliation(s)
- Takumi Takata
- Kyoto University Institute for Integrated Radiation and Nuclear ScienceOsakaJapan
| | - Seongmin Ha
- Department of ChemistryGraduate School of Science, Kyoto UniversityKyotoJapan
| | | | - Noriko Fujii
- Kyoto University Institute for Integrated Radiation and Nuclear ScienceOsakaJapan
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9
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Forsythe HM, Vetter CJ, Jara KA, Reardon PN, David LL, Barbar EJ, Lampi KJ. Altered Protein Dynamics and Increased Aggregation of Human γS-Crystallin Due to Cataract-Associated Deamidations. Biochemistry 2019; 58:4112-4124. [PMID: 31490062 PMCID: PMC10693687 DOI: 10.1021/acs.biochem.9b00593] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Deamidation is a major age-related modification in the human lens that is highly prevalent in crystallins isolated from the insoluble fraction of cataractous lenses and also causes protein aggregation in vitro. However, the mechanism by which deamidation causes proteins to become insoluble is not known because only subtle structural changes were observed in vitro. We have identified Asn14 and Asn76 of γS-crystallin as highly deamidated in insoluble proteins isolated from aged lenses. These sites are on the surface of the N-terminal domain and were mimicked by replacing the Asn with Asp residues in order to generate recombinant human γS and deamidated mutants. Both N14D and N76D had increased light scattering compared to wild-type γS (WT) and increased aggregation during thermal-induced denaturation. Aggregation was enhanced by oxidized glutathione, suggesting deamidation may increase susceptibility to form disulfide bonds. These changes were correlated to changes in protein dynamics determined by NMR spectroscopy. Heteronuclear NMR spectroscopy was used to measure amide hydrogen exchange and 15N relaxation dynamics to identify regions with increased dynamics compared to γS WT. Residue-specific changes in solvent accessibility and dynamics were both near and distant from the sites of deamidation, suggesting that deamidation had both local and global effects on the protein structure at slow (ms to s) and fast (μs to ps) time scales. Thus, a potential mechanism for γS deamidation-induced insolubilization in cataractous lenses is altered dynamics due to local regions of unfolding and increased flexibility in both the N- and C-terminal domains particularly at surface helices. This conformational flexibility increases the likelihood of aggregation, which would be enhanced in the oxidizing cytoplasm of the aged and cataractous lens. The NMR data combined with the in vivo insolubility and in vitro aggregation findings support a model that deamidation drives changes in protein dynamics that facilitate protein aggregation associated with cataracts.
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Affiliation(s)
| | - Calvin J. Vetter
- Integrative Biosciences, Oregon Health & Science University, Portland, OR
| | - Kayla Ann Jara
- Biochemistry & Biophysics, Oregon State University, Corvallis, OR
| | - Patrick N. Reardon
- Nuclear Magnetic Resonance Facility, Oregon State University, Corvallis, OR
| | - Larry L. David
- Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, OR
| | - Elisar J. Barbar
- Biochemistry & Biophysics, Oregon State University, Corvallis, OR
| | - Kirsten J. Lampi
- Integrative Biosciences, Oregon Health & Science University, Portland, OR
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10
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Zarkar N, Khalili MAN, Ahmadpour F, Khodadadi S, Zeinoddini M. In Silico and in Vitro Evaluation of Deamidation Effects on the Stability of the Fusion Toxin DAB389IL-2. CURR PROTEOMICS 2019. [DOI: 10.2174/1570164616666190131150033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background:
DAB389IL-2 (Denileukin diftitox) as an immunotoxin is a targeted pharmaceutical
protein and is the first immunotoxin approved by FDA. It is used for the treatment of various
kinds of cancer such as CTCL lymphoma, melanoma, and Leukemia but among all of these, treatment
of CTCL has special importance. DAB389IL-2 consists of two distinct parts; the catalytic domain of
Diphtheria Toxin (DT) that genetically fused to the whole IL-2. Deamidation is the most important reaction
for chemical instability of proteins occurs during manufacture and storage. Deamidation of asparagine
residues occurs at a higher rate than glutamine residues. The structure of proteins, temperature
and pH are the most important factors that influence the rate of deamidation.
Methods:
Since there is not any information about deamidation of DAB389IL-2, we studied in silico
deamidation by Molecular Dynamic (MD) simulations using GROMACS software. The 3D model of
fusion protein DAB389IL-2 was used as a template for deamidation. Then, the stability of deamidated
and native form of the drug was calculated.
Results:
The results of MD simulations were showed that the deamidated form of DAB389IL-2 is more
unstable than the normal form. Also, deamidation was carried by incubating DAB389IL-2, 0.3 mg/ml in
ammonium hydrogen carbonate for 24 h at 37o C in order to in vitro experiment.
Conclusion:
The results of in vitro experiment were confirmed outcomes of in silico study. In silico
and in vitro experiments were demonstrated that DAB389IL-2 is unstable in deamidated form.
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Affiliation(s)
- Nasrin Zarkar
- Department of Biosciences & Biotechnology, Malek Ashtar University of Technology, Tehran, Iran
| | | | - Fathollah Ahmadpour
- Trauma Research Centre, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Sirus Khodadadi
- Department of Biosciences & Biotechnology, Malek Ashtar University of Technology, Tehran, Iran
| | - Mehdi Zeinoddini
- Department of Biosciences & Biotechnology, Malek Ashtar University of Technology, Tehran, Iran
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11
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Takata T, Murakami K, Toyama A, Fujii N. Identification of Isomeric Aspartate residues in βB2-crystallin from Aged Human Lens. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:767-774. [DOI: 10.1016/j.bbapap.2018.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 12/17/2022]
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12
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Gu J, Tong H, Sun L, Lin Z. Molecular dynamics perspective on the thermal stability of mandelate racemase. J Biomol Struct Dyn 2018; 37:383-393. [PMID: 29334318 DOI: 10.1080/07391102.2018.1427631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mandelate racemase from Pseudomonas putida is a promising candidate for the dynamic kinetic resolution of α-hydroxy carboxylic acids. In the present study, the thermal stability of mandelate racemase was investigated through molecular dynamics simulations in the temperature range of 303-363 K, which can guide the design of mandelate racemase with higher stability. The basic features such as radius of gyration, surface accessibility, and secondary structure content suggested the instability of mandelate racemase at high temperatures. With increase in temperature, α-helix content reduced significantly, especially the α-helices exposed to the environment. At the simulation time scale considered, intra-protein hydrogen bonds, hydrogen bonds between protein and water decreased at 363 K, while the number of salt-bridges increased. The long-distance networks remarkably changed at 363 K. A considerable number of long-lived (percentage existence time higher than 90%) hydrogen bonds and Cα contacts were lost. Root mean square fluctuation analysis revealed regions with high fluctuation, which should be helpful in the reengineering of mandelate racemase for enhanced thermal stability.
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Affiliation(s)
- Jiali Gu
- a College of Life Sciences , Huzhou University , Huzhou , Zhejiang , 313000 , China
| | - Hongfei Tong
- a College of Life Sciences , Huzhou University , Huzhou , Zhejiang , 313000 , China
| | - Laiyu Sun
- a College of Life Sciences , Huzhou University , Huzhou , Zhejiang , 313000 , China
| | - Zhijian Lin
- b Novel Search Center , Zhejiang Institute of Scientific and Technological Information , Hangzhou , Zhejiang , 310052 , China
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13
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Nielsen NS, Juhl DW, Poulsen ET, Lukassen MV, Poulsen EC, Risør MW, Scavenius C, Enghild JJ. Mutation-Induced Deamidation of Corneal Dystrophy-Related Transforming Growth Factor β-Induced Protein. Biochemistry 2017; 56:6470-6480. [PMID: 29140698 DOI: 10.1021/acs.biochem.7b00668] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mutations in the transforming growth factor β-induced protein (TGFBIp) cause phenotypically diverse corneal dystrophies, where protein aggregation in the cornea leads to severe visual impairment. Previous studies have shown a relationship between mutant-specific corneal dystrophy phenotypes and the thermodynamic stability of TGFBIp. Using liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance (NMR), we investigated correlations between the structural integrity of disease-related mutants of the fourth FAS1 domain (FAS1-4) and deamidation of TGFBIp residue Asn622. We observed a high rate of Asn622 deamidation in the A546D and A546D/P551Q FAS1-4 mutants that were both largely unstructured as determined by NMR. Conversely, the more structurally organized A546T and V624M FAS1-4 mutants had reduced deamidation rates, suggesting that a folded and stable FAS1-4 domain precludes Asn622 deamidation. Wild-type, R555Q, and R555W FAS1-4 mutants displayed very slow deamidation, which agrees with their similar and ordered NMR structures, where Asn622 is in a locked conformation. We confirmed the FAS1-4 mutational effect on deamidation rates in full-length TGFBIp mutants and found a similar ranking compared to that of the FAS1-4 domain alone. Consequently, the deamidation rate of Asn622 can be used to predict the structural effect of the many destabilizing and/or stabilizing mutations reported for TGFBIp. In addition, the deamidation of Asn622 may influence the pathophysiology of TGFBIp-induced corneal dystrophies.
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Affiliation(s)
- Nadia Sukusu Nielsen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Dennis Wilkens Juhl
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Ebbe Toftgaard Poulsen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Marie V Lukassen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Emil Christian Poulsen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Michael W Risør
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Carsten Scavenius
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Jan J Enghild
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University , DK-8000 Aarhus, Denmark
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14
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Hao P, Adav SS, Gallart-Palau X, Sze SK. Recent advances in mass spectrometric analysis of protein deamidation. MASS SPECTROMETRY REVIEWS 2017; 36:677-692. [PMID: 26763661 DOI: 10.1002/mas.21491] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Revised: 12/28/2015] [Accepted: 12/28/2015] [Indexed: 06/05/2023]
Abstract
Protein deamidation has been proposed to represent a "molecular clock" that progressively disrupts protein structure and function in human degenerative diseases and natural aging. Importantly, this spontaneous process can also modify therapeutic proteins by altering their purity, stability, bioactivity, and antigenicity during drug synthesis and storage. Deamidation occurs non-enzymatically in vivo, but can also take place spontaneously in vitro, hence artificial deamidation during proteomic sample preparation can hamper efforts to identify and quantify endogenous deamidation of complex proteomes. To overcome this, mass spectrometry (MS) can be used to conduct rigorous site-specific characterization of protein deamidation due to the high sensitivity, speed, and specificity offered by this technique. This article reviews recent progress in MS analysis of protein deamidation and discusses the strengths and limitations of common "top-down" and "bottom-up" approaches. Recent advances in sample preparation methods, chromatographic separation, MS technology, and data processing have for the first time enabled the accurate and reliable characterization of protein modifications in complex biological samples, yielding important new data on how deamidation occurs across the entire proteome of human cells and tissues. These technological advances will lead to a better understanding of how deamidation contributes to the pathology of biological aging and major degenerative diseases. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:677-692, 2017.
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Affiliation(s)
- Piliang Hao
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Sunil S Adav
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Xavier Gallart-Palau
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
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15
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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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16
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Gallart-Palau X, Lee BST, Adav SS, Qian J, Serra A, Park JE, Lai MKP, Chen CP, Kalaria RN, Sze SK. Gender differences in white matter pathology and mitochondrial dysfunction in Alzheimer's disease with cerebrovascular disease. Mol Brain 2016; 9:27. [PMID: 26983404 PMCID: PMC4794845 DOI: 10.1186/s13041-016-0205-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 02/22/2016] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Dementia risk in women is higher than in men, but the molecular neuropathology of this gender difference remains poorly defined. In this study, we used unbiased, discovery-driven quantitative proteomics to assess the molecular basis of gender influences on risk of Alzheimer's disease with cerebrovascular disease (AD + CVD). RESULTS We detected modulation of several redox proteins in the temporal lobe of AD + CVD subjects, and we observed sex-specific alterations in the white matter (WM) and mitochondria proteomes of female patients. Functional proteomic analysis of AD + CVD brain tissues revealed increased citrullination of arginine and deamidation of glutamine residues of myelin basic protein (MBP) in female which impaired degradation of degenerated MBP and resulted in accumulation of non-functional MBP in WM. Female patients also displayed down-regulation of ATP sub-units and cytochromes, suggesting increased severity of mitochondria impairment in women. CONCLUSIONS Our study demonstrates that gender-linked modulation of white matter and mitochondria proteomes influences neuropathology of the temporal lobe in AD + CVD.
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Affiliation(s)
- Xavier Gallart-Palau
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Benjamin S. T. Lee
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Sunil S. Adav
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Jingru Qian
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Aida Serra
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Jung Eun Park
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Mitchell K. P. Lai
- />Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Christopher P. Chen
- />Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- />Memory, Aging and Cognition Centre, National University Health System, Singapore, Singapore
| | - Raj N. Kalaria
- />Institute for Ageing and Health, NIHR Biomedical Research Building, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL UK
| | - Siu Kwan Sze
- />Division of Chemical Biology & BioTechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
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17
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Takata T, Fujii N. Isomerization of Asp residues plays an important role in αA-crystallin dissociation. FEBS J 2016; 283:850-9. [PMID: 26700637 DOI: 10.1111/febs.13635] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/08/2015] [Accepted: 12/18/2015] [Indexed: 11/29/2022]
Abstract
Aged cataract formation is caused by the accumulative precipitation of lens proteins incorporating diverse post-translational modifications. α-Crystallin, a major structural and functional lens protein, consists of a large polymeric structure that is dissociated and insolubilized with accumulative post-translational modifications. One such modification, isomerization of Asp, was recently identified in αB-crystallin monomers derived from aged lens. However, the distributions of Asp isomers in each lens fraction remain unknown. Here, α-crystallin fractions from aged lens were separated into heteropolymeric and monomeric forms to determine the Asp isomerization ratios in each fraction. Lens of four different ages were homogenized and centrifuged, and the soluble fraction was applied to size-exclusion chromatography. The heteropolymeric α-crystallin and monomeric crystallin fractions were obtained and concentrated. After trypsin digestion, each fraction was independently applied to liquid chromatography equipped with mass spectrometry to extract α-crystallin-derived peptides containing Asp isomers. The results showed that Asp58, Asp84 and Asp151 of αA-crystallin were highly isomerized in the monomeric fraction, but not isomerized to the same level in the heteropolymeric fraction. Each type of Asp isomerization increased in an age-dependent manner, was site-specific and was similar to previous results from lens water-insoluble fractions. These results imply that isomerization of Asp residues leads to dissociation of αA-crystallin from the heteropolymeric state and induces insolubilization in aged lens. Taken together, our findings suggest that isomerization of Asp might disrupt the higher order polymeric state of α-crystallin, resulting in decreased solubility and function, ultimately contributing to lens protein impairment and cataract formation with aging.
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Affiliation(s)
- Takumi Takata
- Department of Biochemistry, Tokyo University of Pharmacy and Life Sciences, Japan
| | - Noriko Fujii
- Research Reactor Institute, Kyoto University, Osaka, Japan
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18
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Kori Y, Patel R, Neill A, Liu H. A conventional procedure to reduce Asn deamidation artifacts during trypsin peptide mapping. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1009-1010:107-13. [DOI: 10.1016/j.jchromb.2015.12.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 12/04/2015] [Accepted: 12/07/2015] [Indexed: 12/12/2022]
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19
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Tiwary E, Hegde S, Purushotham S, Deivanayagam C, Srivastava O. Interaction of βA3-Crystallin with Deamidated Mutants of αA- and αB-Crystallins. PLoS One 2015; 10:e0144621. [PMID: 26657544 PMCID: PMC4691197 DOI: 10.1371/journal.pone.0144621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/22/2015] [Indexed: 11/18/2022] Open
Abstract
Interaction among crystallins is required for the maintenance of lens transparency. Deamidation is one of the most common post-translational modifications in crystallins, which results in incorrect interaction and leads to aggregate formation. Various studies have established interaction among the α- and β-crystallins. Here, we investigated the effects of the deamidation of αA- and αB-crystallins on their interaction with βA3-crystallin using surface plasmon resonance (SPR) and fluorescence lifetime imaging microscopy-fluorescence resonance energy transfer (FLIM-FRET) methods. SPR analysis confirmed adherence of WT αA- and WT αB-crystallins and their deamidated mutants with βA3-crystallin. The deamidated mutants of αA–crystallin (αA N101D and αA N123D) displayed lower adherence propensity for βA3-crystallin relative to the binding affinity shown by WT αA-crystallin. Among αB-crystallin mutants, αB N78D displayed higher adherence propensity whereas αB N146D mutant showed slightly lower binding affinity for βA3-crystallin relative to that shown by WT αB-crystallin. Under the in vivo condition (FLIM-FRET), both αA-deamidated mutants (αA N101D and αA N123D) exhibited strong interaction with βA3-crystallin (32±4% and 36±4% FRET efficiencies, respectively) compared to WT αA-crystallin (18±4%). Similarly, the αB N78D and αB N146D mutants showed strong interaction (36±4% and 22±4% FRET efficiencies, respectively) with βA3-crystallin compared to 18±4% FRET efficiency of WT αB-crystallin. Further, FLIM-FRET analysis of the C-terminal domain (CTE), N-terminal domain (NTD), and core domain (CD) of αA- and αB-crystallins with βA3-crystallin suggested that interaction sites most likely reside in the αA CTE and αB NTD regions, respectively, as these domains showed the highest FRET efficiencies. Overall, results suggest that similar to WT αA- and WTαB-crystallins, the deamidated mutants showed strong interactionfor βA3-crystallin. Variable in vitro and in vivo interactions are most likely due to the mutant’s large size oligomers, reduced hydrophobicity, and altered structures. Together, the results suggest that deamidation of α-crystallin may facilitate greater interaction and the formation of large oligomers with other crystallins, and this may contribute to the cataractogenic mechanism.
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Affiliation(s)
- Ekta Tiwary
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, 35294, United States of America
| | - Shylaja Hegde
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, 35294, United States of America
| | - Sangeetha Purushotham
- Department of Vision Sciences/Centre for Structural Biology, University of Alabama at Birmingham, Birmingham, Alabama, 35294, United States of America
| | - Champion Deivanayagam
- Department of Vision Sciences/Centre for Structural Biology, University of Alabama at Birmingham, Birmingham, Alabama, 35294, United States of America
| | - Om Srivastava
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, 35294, United States of America
- * E-mail:
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20
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Effect of Asp 96 isomerization on the properties of a lens αB-crystallin-derived short peptide. J Pharm Biomed Anal 2015; 116:139-44. [DOI: 10.1016/j.jpba.2015.06.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 05/28/2015] [Accepted: 06/10/2015] [Indexed: 11/21/2022]
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21
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Pande A, Mokhor N, Pande J. Deamidation of Human γS-Crystallin Increases Attractive Protein Interactions: Implications for Cataract. Biochemistry 2015; 54:4890-9. [PMID: 26158710 DOI: 10.1021/acs.biochem.5b00185] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Deamidation of proteins is one of the most prevalent post-translational modifications found upon aging, and in age-onset diseases. Specific asparagine and glutamine residues are often selectively deamidated during this process. In the human lens, deamidation has been shown to occur in many crystallins, but it is not clear how these deamidated proteins lead to lens opacity or cataract. Here we have modeled in vitro the effect of deamidation of specific asparagine and glutamine residues in human recombinant γS-crystallin (HGS) on the solution properties of the protein. The residues selected for deamidation in vitro are those that are found to be deamidated in aged and cataractous lenses in vivo. Two derivatives were prepared, one with Asn76 and Asn143 deamidated (2N-HGS) and the other with two additional Gln residues (92 and 120) deamidated (2N2Q-HGS). Isoelectric focusing measurements showed the expected lowering of the pI from 6.9 in HGS to ∼6.5 in 2N-HGS and to ∼6.1 in 2N2Q-HGS. However, spectroscopic studies showed no significant change in the secondary and tertiary structures of the deamidated proteins relative to the wild type. The stability of 2N-HGS and 2N2Q-HGS, as measured by guanidinium hydrochloride unfolding, also remained comparable to that of HGS. The main difference was the altered protein-protein interaction among the three proteins. The net repulsive interactions that are characteristic of HGS are diminished in the deamidated derivatives as evidenced by static light scattering measurements of the second virial coefficient, B2 (B2 values for HGS, 2N-HGS, and 2N2Q-HGS of 8.90 × 10(-4), 7.10 × 10(-4), and 6.65 × 10(-4) mL mol g(-2), respectively). Further substantiation is provided by estimates of the excess binding energy of protein-protein interactions in the condensed phase, obtained from measurements of the PEG-induced liquid-liquid phase separation profiles for the three proteins. The data suggest that enhanced attractive protein-protein interactions, arising from the deamidation of HGS, promote protein aggregation, thereby leading to increased light scattering and opacity over time.
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Affiliation(s)
- Ajay Pande
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Natalya Mokhor
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Jayanti Pande
- Department of Chemistry, Life Sciences 2070, University at Albany, State University of New York, Albany, New York 12222, United States
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22
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Lampi KJ, Murray MR, Peterson MP, Eng BS, Yue E, Clark AR, Barbar E, David LL. Differences in solution dynamics between lens β-crystallin homodimers and heterodimers probed by hydrogen-deuterium exchange and deamidation. Biochim Biophys Acta Gen Subj 2015; 1860:304-14. [PMID: 26145577 DOI: 10.1016/j.bbagen.2015.06.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/12/2015] [Accepted: 06/18/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Lens transparency is due to the ordered arrangement of the major structural proteins, called crystallins. βB2 crystallin in the lens of the eye readily forms dimers with other β-crystallin subunits, but the resulting heterodimer structures are not known and were investigated in this study. METHODS Structures of βA3 and βB2 crystallin homodimers and the βA3/βB2 crystallin heterodimers were probed by measuring changes in solvent accessibility using hydrogen-deuterium exchange with mass spectrometry. We further mimicked deamidation in βB2 and probed the effect on the βA3/βB2 heterodimer. Results were confirmed with chemical crosslinking and NMR. RESULTS Both βA3 and βB2 had significantly decreased deuterium levels in the heterodimer compared to their respective homodimers, suggesting that they had less solvent accessibility and were more compact in the heterodimer. The compact structure of βB2 was supported by the identification of chemical crosslinks between lysines in βB2 within the heterodimer that were inconsistent with βB2's extended homodimeric structure. The compact structure of βA3 was supported by an overall decrease in mobility of βA3 in the heterodimer detected by NMR. In βB2, peptides 70-84 and 121-134 were exposed in the homodimer, but buried in the heterodimer with ≥50% decreases in deuterium levels. Homologous peptides in βA3, 97-109 and 134-149, had 25-50% decreases in deuterium levels in the heterodimer. These peptides are probable sites of interaction between βB2 and βA3 and are located at the predicted interface between subunits with bent linkers. Deamidation at Q184 in βB2 at this predicted interface led to a less compact βB2 in the heterodimer. The more compact structure of the βA3/βB2 heterodimer was also more heat stable than either of the homodimers. CONCLUSIONS The major structural proteins in the lens, the β-crystallins, are not static, but dynamic in solution, with differences in accessibility between the homo-and hetero-dimers. This structural flexibility, particularly of βB2, may facilitate formation of different size higher-ordered structures found in the transparent lens. GENERAL SIGNIFICANCE Understanding complex hetero-oligomer interactions between β-crystallins in normal lens and how these interactions change during aging is fundamental to understanding the cause of cataracts. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Kirsten J Lampi
- Integrative Biosciences, Oregon Health & Science University, Portland, OR 97239-3098, United States.
| | - Matthew R Murray
- Integrative Biosciences, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Matthew P Peterson
- Integrative Biosciences, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Bryce S Eng
- Integrative Biosciences, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Eileen Yue
- Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Alice R Clark
- Birkbeck College, University of London, United Kingdom
| | - Elisar Barbar
- Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, United States
| | - Larry L David
- Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239-3098, United States
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23
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Maeda H, Takata T, Fujii N, Sakaue H, Nirasawa S, Takahashi S, Sasaki H, Fujii N. Rapid Survey of Four Asp Isomers in Disease-Related Proteins by LC-MS combined with Commercial Enzymes. Anal Chem 2014; 87:561-8. [DOI: 10.1021/ac504413e] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Hiroki Maeda
- Department
of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takumi Takata
- Research
Reactor Institute, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Norihiko Fujii
- Radioisotope
Research Center, Teikyo University, Kaga Itabashi-ku, Tokyo 173-8605, Japan
| | - Hiroaki Sakaue
- International University of Health and Welfare, Ohtawara, Tochigi 324-8501, Japan
| | - Satoru Nirasawa
- Japan International
Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan
| | - Saori Takahashi
- Akita Research Institute
of Food and Brewing, Akita, 010-1623, Japan
| | - Hiroshi Sasaki
- Kanazawa Medical University, Kanazawa, Ishikawa 920-0293, Japan
| | - Noriko Fujii
- Department
of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Research
Reactor Institute, Kyoto University Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
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Bhanuramanand K, Ahmad S, Rao NM. Engineering deamidation-susceptible asparagines leads to improved stability to thermal cycling in a lipase. Protein Sci 2014; 23:1479-90. [PMID: 25043738 DOI: 10.1002/pro.2516] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/09/2014] [Accepted: 07/10/2014] [Indexed: 01/15/2023]
Abstract
At high temperatures, protein stability is influenced by chemical alterations; most important among them is deamidation of asparagines. Deamidation kinetics of asparagines depends on the local sequence, solvent, pH, temperature, and the tertiary structure. Suitable replacement of deamidated asparagines could be a viable strategy to improve deamidation-mediated loss in protein properties, specifically protein thermostability. In this study, we have used nano RP-HPLC coupled ESI MS/MS approach to identify residues susceptible to deamidation in a lipase (6B) on heat treatment. Out of 15 asparagines and six glutamines in 6B, only five asparagines were susceptible to deamidation at temperatures higher than 75°C. These five positions were subjected to site saturation mutagenesis followed by activity screen to identify the most suitable substitutions. Only three of the five asparagines were found to be tolerant to substitutions. Best substitutions at these positions were combined into a mutant. The resultant lipase (mutC) has near identical secondary structure and improved thermal tolerance as compared to its parent. The triple mutant has shown almost two-fold higher residual activity compared to 6B after four cycles at 90°C. MutC has retained more than 50% activity even after incubation at 100°C. Engineering asparagines susceptible to deamidation would be a potential strategy to improve proteins to withstand very high temperatures.
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Affiliation(s)
- K Bhanuramanand
- Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, 500007, India
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25
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Structure-based prediction of asparagine and aspartate degradation sites in antibody variable regions. PLoS One 2014; 9:e100736. [PMID: 24959685 PMCID: PMC4069079 DOI: 10.1371/journal.pone.0100736] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 05/30/2014] [Indexed: 12/29/2022] Open
Abstract
Monoclonal antibodies (mAbs) and proteins containing antibody domains are the most prevalent class of biotherapeutics in diverse indication areas. Today, established techniques such as immunization or phage display allow for an efficient generation of new mAbs. Besides functional properties, the stability of future therapeutic mAbs is a key selection criterion which is essential for the development of a drug candidate into a marketed product. Therapeutic proteins may degrade via asparagine (Asn) deamidation and aspartate (Asp) isomerization, but the factors responsible for such degradation remain poorly understood. We studied the structural properties of a large, uniform dataset of Asn and Asp residues in the variable domains of antibodies. Their structural parameters were correlated with the degradation propensities measured by mass spectrometry. We show that degradation hotspots can be characterized by their conformational flexibility, the size of the C-terminally flanking amino acid residue, and secondary structural parameters. From these results we derive an accurate in silico prediction method for the degradation propensity of both Asn and Asp residues in the complementarity-determining regions (CDRs) of mAbs.
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26
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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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27
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Lampi KJ, Wilmarth PA, Murray MR, David LL. Lens β-crystallins: the role of deamidation and related modifications in aging and cataract. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:21-31. [PMID: 24613629 DOI: 10.1016/j.pbiomolbio.2014.02.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 02/12/2014] [Accepted: 02/14/2014] [Indexed: 11/26/2022]
Abstract
Crystallins are the major proteins in the lens of the eye and function to maintain transparency of the lens. Of the human crystallins, α, β, and γ, the β-crystallins remain the most elusive in their structural significance due to their greater number of subunits and possible oligomer formations. The β-crystallins are also heavily modified during aging. This review focuses on the functional significance of deamidation and the related modifications of racemization and isomerization, the major modifications in β-crystallins of the aged human lens. Elucidating the role of these modifications in cataract formation has been slow, because they are analytically among the most difficult post-translational modifications to study. Recent results suggest that many amides deamidate to similar extent in normal aged and cataractous lenses, while others may undergo greater deamidation in cataract. Mimicking deamidation at critical structural regions induces structural changes that disrupt the stability of the β-crystallins and lead to their aggregation in vitro. Deamidations at the surface disrupt interactions with other crystallins. Additionally, the α-crystallin chaperone is unable to completely prevent deamidated β-crystallins from insolubilization. Therefore, deamidation of β-crystallins may enhance their precipitation and light scattering in vivo contributing to cataract formation. Future experiments are needed to quantify differences in deamidation rates at all Asn and Gln residues within crystallins from aged and cataractous lenses, as well as racemization and isomerization which potentially perturb protein structure greater than deamidation alone. Quantitative data is greatly needed to investigate the importance of these major age-related modifications in cataract formation.
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Affiliation(s)
- Kirsten J Lampi
- Oregon Health & Science University, Integrative Biosciences, 611 SW Campus Drive, Portland, OR 97239, USA.
| | - Phillip A Wilmarth
- Oregon Health & Science University, Biochemistry and Molecular Biology, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, USA
| | - Matthew R Murray
- Oregon Health & Science University, Integrative Biosciences, 611 SW Campus Drive, Portland, OR 97239, USA
| | - Larry L David
- Oregon Health & Science University, Biochemistry and Molecular Biology, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, USA
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28
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Kanemaki N, Fukiage C, Ichikawa Y, Shearer TR, Azuma M. Serum antibodies against βH-crystallins in the American Cocker Spaniel. Vet Ophthalmol 2013; 18:109-15. [PMID: 24171837 PMCID: PMC4371642 DOI: 10.1111/vop.12113] [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] [Indexed: 11/30/2022]
Abstract
Objective To detect antibodies for lens βH-crystallins in the serum from the American Cocker Spaniel (ACS) presenting with and without cataracts and with and without uveitis. Animal Studied Seventy-three American Cocker Spaniels and six normal Beagles. Procedures Sera were collected from 73 ACSs, including those with normal lenses and those with cataracts, or uveitis. Fractionated, normal Beagle lens βH-crystallins were separated by one- or two-dimensional electrophoresis. The separated lens βH-crystallins were used on immunoblots as sentinel substrates against which the ACS sera were tested for the presence of antibodies against βH-crystallins. Results Sera from approximately two-thirds of study animals contained antibodies to some βH-crystallin polypeptides, but reactivity varied among patients. Contrary to some hypotheses, serum antibodies to groups of βH-crystallins did not relate to the stages of cataract. However, detailed analysis by two-dimensional immunoblotting and mass spectrometry showed that three spots originating from βA1-crystallin were detected only in sera from cataract patients. Conclusion Serum antibodies to βA1-crystallin may be associated with the development of cataract.
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Affiliation(s)
- Nobuyuki Kanemaki
- Veterinary Teaching Hospital, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, 2525201, Japan
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29
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Karri S, Kasetti RB, Vendra VPR, Chandani S, Balasubramanian D. Structural analysis of the mutant protein D26G of human γS-crystallin, associated with Coppock cataract. Mol Vis 2013; 19:1231-7. [PMID: 23761725 PMCID: PMC3675056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 06/03/2013] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To analyze the protein structural features responsible for the aggregation properties of the mutant protein D26G human γS-crystallin (HGSC) associated with congenital Coppock-type cataract. METHODS cDNAs of wild-type (WT) and D26G mutant HGSC were cloned and expressed in BL21 (DE3) pLysS cells and the proteins isolated and purified. Their secondary and tertiary structural features, aggregation tendencies, and structural stabilities were compared using spectroscopic (circular dichroism, intrinsic and extrinsic fluorescence), molecular modeling, and dynamics methods. RESULTS No difference was observed between the conformational (secondary and tertiary structural) features and aggregation properties between the WT and D26G proteins. The mutant, however, was structurally less stable; it denatured at a slightly lower concentration of the added chemical denaturant (at 2.05 M guanidinium chloride, cf. 2.20 M for the WT) and at a slightly lower temperature (at 70.8 °C, cf. 72.0 °C for the WT). The mutant also self-aggregated more readily (it turned turbid upon standing; at 65 °C, it started precipitating beyond 200 s, while the WT did not, even after 900 s). Molecular modeling showed that the Asp26-Arg84 contact (and the related Arg84-Asn54 interaction) was disturbed in the mutant, making the latter less compact around the mutation site. CONCLUSIONS The cataract-associated mutant D26G of HGSC is remarkably close to the WT molecule in structural features, with only a microenvironmental change in the packing around the mutation site. This alteration appears sufficient to promote self-aggregation, resulting in peripheral cataract.
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Affiliation(s)
- Srinivasu Karri
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad, India
| | - Ramesh Babu Kasetti
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad, India
| | - Venkata Pulla Rao Vendra
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad, India
| | | | - Dorairajan Balasubramanian
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad, India
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30
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Lampi KJ, Fox CB, David LL. Changes in solvent accessibility of wild-type and deamidated βB2-crystallin following complex formation with αA-crystallin. Exp Eye Res 2012; 104:48-58. [PMID: 22982024 DOI: 10.1016/j.exer.2012.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 09/01/2012] [Accepted: 09/03/2012] [Indexed: 10/27/2022]
Abstract
Aberrant protein interactions can lead to aggregation and insolubilization, such as occurs during cataract formation. Deamidation, a prevalent age-related modification in the lens of the eye, decreases stability of the major lens proteins, crystallins. The mechanism of deamidation altering interactions between αA-crystallin and βB2-crystallin was investigated by detecting changes in solvent accessibility upon complex formation during heating. Solvent accessibility was determined by measuring hydrogen/deuterium exchange levels of backbone amides by high-resolution mass spectrometry. Deuterium levels in wild type βB2-crystallin increased 50-60% in both domains following complex formation with αA-crystallin. This increased solvent accessibility indicated a general loosening along the backbone amides. Peptides with the greatest deuterium increases were located at the buried monomer-monomer interface, suggesting that the βB2 dimer was disrupted. The only region where the deuterium levels decreased was in βB2 peptide 123-139, containing an outside loop, and may be a potential site of interaction with αA. Mimicking deamidation at the βB2 dimer interface prevented complex formation with αA. When temperatures were lowered, an αA/βB2 Q70E/Q162E complex formed with similar solvent accessibilities as αA/WT βB2. Deamidation did not disrupt specific αA/βB2 interactions but favored aggregation before complex formation with αA. We conclude that deamidation contributes to cataract formation through destabilization of crystallins before they can be rescued by α-crystallin.
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Affiliation(s)
- Kirsten J Lampi
- Oregon Health and Science University, Integrative Biosciences, 611 SW Campus Dr., Portland, OR 97239, USA.
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31
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Cataract-causing defect of a mutant γ-crystallin proceeds through an aggregation pathway which bypasses recognition by the α-crystallin chaperone. PLoS One 2012; 7:e37256. [PMID: 22655036 PMCID: PMC3360035 DOI: 10.1371/journal.pone.0037256] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Accepted: 04/18/2012] [Indexed: 11/19/2022] Open
Abstract
Background The transparency of the eye lens depends upon maintenance of the native state of the γ- and β-crystallins, which is aided by the abundant chaperones αA- and αB-crystallin. Mature onset cataract, the leading cause of blindness worldwide, involves the polymerization of covalently damaged or partially unfolded crystallins into light-scattering aggregates. A number of single amino acid substitutions and truncations of γ-crystallins result in congenital cataract in both humans and mice, though in many cases the coupling between the protein alterations and the accumulation of aggregates is poorly defined. Methodology/Principal Findings We have studied the aggregation properties and chaperone interactions of human γD-crystallin carrying substitutions of two buried core mutants, I90F and V75D, which cause congenital cataract in mice. The in vitro aggregation pathway competing with productive refolding was not altered by either substitution. Furthermore, this aggregation pathway for both mutant proteins–originating from a partially folded intermediate–was efficiently suppressed by αB-crystallin. Thus the cataract pathology was unlikely to be associated with a direct folding defect. The native state of wild-type human γD-crystallin exhibited no tendency to aggregate under physiological conditions. However both I90F and V75D native-like proteins exhibited slow (days) aggregation to high molecular weight aggregates under physiological conditions. The perturbed conformation of I90F was recognized and bound by both αA and αB chaperones. In contrast, the aggregation derived from the perturbed state of V75D was not suppressed by either chaperone, and the aggregating species were not bound by the chaperone. Conclusions/Significance The cataract phenotype of I90F in mice may be due to premature saturation of the finite α- crystallin pool. The V75D aggregation pathway and its escape from chaperone surveillance and aggregation suppression can account for the congenital cataract pathology of this mutant. Failure of chaperone recognition may be an important source of pathology for many other protein folding defects.
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32
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Truscott RJW, Mizdrak J, Friedrich MG, Hooi MY, Lyons B, Jamie JF, Davies MJ, Wilmarth PA, David LL. Is protein methylation in the human lens a result of non-enzymatic methylation by S-adenosylmethionine? Exp Eye Res 2012; 99:48-54. [PMID: 22542751 DOI: 10.1016/j.exer.2012.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 04/05/2012] [Accepted: 04/05/2012] [Indexed: 01/02/2023]
Abstract
Since crystallins in the human lens do not turnover, they are susceptible to modification by reactive molecules over time. Methylation is a major post-translational lens modification, however the source of the methyl group is not known and the extent of modification across all crystallins has yet to be determined. Sites of methylation in human lens proteins were determined using HPLC/mass spectrometry following digestion with trypsin. The overall extent of protein methylation increased with age, and there was little difference in the extent of modification between soluble and insoluble crystallins. Several different cysteine and histidine residues in crystallins from adult lenses were found to be methylated with one cysteine (Cys 110 in γD crystallin) at a level approaching 70%, however, methylation of crystallins was not detected in fetal or newborn lenses. S-adenosylmethionine (SAM) was quantified at significant (10-50 μM) levels in lenses, and in model experiments SAM reacted readily with N-α-tBoc-cysteine and N-α-tBoc-histidine, as well as βA3-crystallin. The pattern of lens protein methylation seen in the human lens was consistent with non-enzymatic alkylation. The in vitro data shows that SAM can act directly to methylate lens proteins and SAM was present in significant concentrations in human lens. Thus, non-enzymatic methylation of crystallins by SAM offers a possible explanation for this major human lens modification.
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33
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Moreau KL, King JA. Protein misfolding and aggregation in cataract disease and prospects for prevention. Trends Mol Med 2012; 18:273-82. [PMID: 22520268 DOI: 10.1016/j.molmed.2012.03.005] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 03/01/2012] [Accepted: 03/14/2012] [Indexed: 11/16/2022]
Abstract
The transparency of the eye lens depends on maintaining the native tertiary structures and solubility of the lens crystallin proteins over a lifetime. Cataract, the leading cause of blindness worldwide, is caused by protein aggregation within the protected lens environment. With age, covalent protein damage accumulates through pathways thought to include UV radiation, oxidation, deamidation, and truncations. Experiments suggest that the resulting protein destabilization leads to partially unfolded, aggregation-prone intermediates and the formation of insoluble, light-scattering protein aggregates. These aggregates either include or overwhelm the protein chaperone content of the lens. Here, we review the causes of cataract and nonsurgical methods being investigated to inhibit or delay cataract development, including natural product-based therapies, modulators of oxidation, and protein aggregation inhibitors.
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Affiliation(s)
- Kate L Moreau
- Massachusetts Institute of Technology, Department of Biology, 77 Massachusetts Avenue, 68-330, Cambridge, MA 02139, USA
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34
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Jha SK, Deepalakshmi PD, Udgaonkar JB. Characterization of deamidation of barstar using electrospray ionization quadrupole time-of-flight mass spectrometry, which stabilizes an equilibrium unfolding intermediate. Protein Sci 2012; 21:633-46. [PMID: 22431291 DOI: 10.1002/pro.2047] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 02/01/2012] [Accepted: 02/13/2012] [Indexed: 11/09/2022]
Abstract
Deamidation of asparaginyl residues is a common posttranslational modification in proteins and has been studied extensively because of its important biological effects, such as those on enzymatic activity, protein folding, and proteolytic degradation. However, characterization of the sites of deamidation of a protein has been a difficult analytical problem. In this study, mass spectrometry has been used as an analytical tool to characterize the deamidation of barstar, an RNAse inhibitor. Upon incubation of the protein at alkaline pH for 5 h, intact mass analysis of barstar, using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI QToF MS), indicated an increase in the mass of +2 Da, suggesting possible deamidation of the protein. The sites of deamidation have been identified using the conventional bottom-up approach using a capillary liquid chromatography connected on line to an ESI QToF mass spectrometer and top down approach by direct infusion of the intact protein and fragmenting inside MS. These chemical modifications are shown to lead to stabilization of an unfolding intermediate, which can be observed in equilibrium unfolding studies.
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Affiliation(s)
- Santosh Kumar Jha
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
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35
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Takata T, Smith JP, Arbogast B, David LL, Lampi KJ. Solvent accessibility of betaB2-crystallin and local structural changes due to deamidation at the dimer interface. Exp Eye Res 2010; 91:336-46. [PMID: 20639133 PMCID: PMC2926248 DOI: 10.1016/j.exer.2010.05.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Revised: 05/24/2010] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
In the lens of the eye the ordered arrangement of the major proteins, the crystallins, contributes to lens transparency. Members of the beta/gamma-crystallin family share common beta-sheet rich domains and hydrophobic regions at the monomer-monomer or domain-domain interfaces. Disruption of these interfaces, due to post-translational modifications, such as deamidation, decreases the stability of the crystallins. Previous experiments have failed to define the structural changes associated with this decreased stability. Using hydrogen/deuterium exchange with mass spectrometry (HDMS), deamidation-induced local structural changes in betaB2-crystallin were identified. Deamidation was mimicked by replacing glutamines with glutamic acids at homologous residues 70 and 162 in the monomer-monomer interface of the betaB2-crystallin dimer. The exchange-in of deuterium was determined from 15 s to 24 h and the global and local changes in solvent accessibility were measured. In the wild type betaB2-crystallin (WT), only about 20% of the backbone amide hydrogen was exchanged, suggesting an overall low accessibility of betaB2-crystallin in solution. This is consistent with a tightly packed domain structure observed in the crystal structure. Deuterium levels were initially greater in N-terminal domain (N-td) peptides than in homologous peptides in the C-terminal domain (C-td). The more rapid incorporation suggests a greater solvent accessibility of the N-td. In the betaB2-crystallin crystal structure, interface Gln are oriented towards their opposite domain. When deamidation was mimicked at Gln70 in the N-td, deuterium levels increased at the interface peptide in the C-td. A similar effect in the N-td was not observed when deamidation was mimicked at the homologous residue, Gln162, in the C-td. This difference in the mutants can be explained by deamidation at Gln70 disrupting the more compact C-td and increasing the solvent accessibility in the C-td interface peptides. When deamidation was mimicked at both interface Gln, deuterium incorporation increased in the C-td, similar to deamidation at Gln70 alone. In addition, deuterium incorporation was decreased in the N-td in an outside loop peptide adjacent to the mutation site. This decreased accessibility may be due to newly exposed charge groups facilitating ionic interactions or to peptides becoming more buried when other regions became more exposed. The highly sensitive HDMS methods used here detected local structural changes in solution that had not been previously identified and provide a mechanism for the associated decrease in stability due to deamidation. Changes in accessibility due to deamidation at the interface led to structural perturbations elsewhere in the protein. The cumulative effects of multiple deamidation sites perturbing the structure both locally and distant from the site of deamidation may contribute to aggregation and precipitation during aging and cataractogenesis in the lens.
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Affiliation(s)
- Takumi Takata
- Oregon Health and Science University, Integrative Biosciences, 611 SW Campus Drive, Portland, OR 97239, USA
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36
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Acosta-Sampson L, King J. Partially folded aggregation intermediates of human gammaD-, gammaC-, and gammaS-crystallin are recognized and bound by human alphaB-crystallin chaperone. J Mol Biol 2010; 401:134-52. [PMID: 20621668 DOI: 10.1016/j.jmb.2010.05.067] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 05/20/2010] [Accepted: 05/26/2010] [Indexed: 11/16/2022]
Abstract
Human gamma-crystallins are long-lived, unusually stable proteins of the eye lens exhibiting duplicated, double Greek key domains. The lens also contains high concentrations of the small heat shock chaperone alpha-crystallin, which suppresses aggregation of model substrates in vitro. Mature-onset cataract is believed to represent an aggregated state of partially unfolded and covalently damaged crystallins. Nonetheless, the lack of cell or tissue culture for anucleate lens fibers and the insoluble state of cataract proteins have made it difficult to identify the conformation of the human gamma-crystallin substrate species recognized by human alpha-crystallin. The three major human lens monomeric gamma-crystallins, gammaD, gammaC, and gammaS, all refold in vitro in the absence of chaperones, on dilution from denaturant into buffer. However, off-pathway aggregation of the partially folded intermediates competes with productive refolding. Incubation with human alphaB-crystallin chaperone during refolding suppressed the aggregation pathways of the three human gamma-crystallin proteins. The chaperone did not dissociate or refold the aggregated chains under these conditions. The alphaB-crystallin oligomers formed long-lived stable complexes with their gammaD-crystallin substrates. Using alpha-crystallin chaperone variants lacking tryptophans, we obtained fluorescence spectra of the chaperone-substrate complex. Binding of substrate gamma-crystallins with two or three of the four buried tryptophans replaced by phenylalanines showed that the bound substrate remained in a partially folded state with neither domain native-like. These in vitro results provide support for protein unfolding/protein aggregation models for cataract, with alpha-crystallin suppressing aggregation of damaged or unfolded proteins through early adulthood but becoming saturated with advancing age.
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Affiliation(s)
- Ligia Acosta-Sampson
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 68-330, Cambridge, MA 02139, USA
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37
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Xu J, Wong C, Tan X, Jing H, Zhou G, Song W. Decreasing the homodimer interaction: a common mechanism shared by the deltaG91 mutation and deamidation in betaA3-crystallin. Mol Vis 2010; 16:438-44. [PMID: 20300566 PMCID: PMC2838740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 03/08/2010] [Indexed: 12/02/2022] Open
Abstract
PURPOSE Cataracts can be broadly divided into two types: congenital cataracts and age-related cataracts. DeltaG91 is a previously discovered congenital mutation in betaA3-crystallin that impairs protein solubility. On the other hand, the deamidation of beta-crystallin is a significant feature in aged and cataractous lenses. Several deamidation sites were also identified in betaA3-crystallin. The present study is to compare the functional consequence of DeltaG91 mutation and the deamidation of betaA3-crystallin in terms of folding properties and protein-protein interaction. METHODS Protein secondary structure and hydrophobic properties were investigated by in silica analysis of the wild type and mutants sequences. Full-length betaA3-crystallin was cloned into a mammalian two-hybrid system in order to investigate protein-protein interactions. Deletion and deamidation were introduced by site-directed mutagenesis protocols. Both the Q85 and Q180 deamidation sites were substituted with glutamic acid residues to mimic deamidation. Different combinations of plasmid constructs were transfected in HeLa cells, and changes of protein-protein interactions were analyzed by the luciferase assay. RESULTS Bioinformatics prediction suggested that DeltaG91 mutation alters both the predicted secondary structure and hydrophobic character of betaA3-crystallin, while deamidation only exhibits minimal effects. Mammalian two-hybrid results indicated that both DeltaG91 mutation and Q85/Q180 deamidation could significantly decrease the interaction of the betaA3-crystallin homodimer. CONCLUSION Our results provided evidence that both mutations involved in congenital cataracts and deamidation in aged lenses commonly altered protein-protein interaction between human lens betaA3-crystallins, which may lead to protein insolubilization and contribute to cataracts.
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Affiliation(s)
- Jianzhen Xu
- College of Bioengineering, Henan University of Technology, Zhengzhou, P.R. China
| | - Chiwai Wong
- Center of Integrative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, P.R. China
| | - Xiaorong Tan
- College of Bioengineering, Henan University of Technology, Zhengzhou, P.R. China
| | - Hongjuan Jing
- College of Bioengineering, Henan University of Technology, Zhengzhou, P.R. China
| | - Guangzhou Zhou
- College of Bioengineering, Henan University of Technology, Zhengzhou, P.R. China
| | - Wei Song
- College of Bioengineering, Henan University of Technology, Zhengzhou, P.R. China
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Michiel M, Duprat E, Skouri-Panet F, Lampi JA, Tardieu A, Lampi KJ, Finet S. Aggregation of deamidated human betaB2-crystallin and incomplete rescue by alpha-crystallin chaperone. Exp Eye Res 2010; 90:688-98. [PMID: 20188088 DOI: 10.1016/j.exer.2010.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 02/02/2010] [Accepted: 02/16/2010] [Indexed: 11/16/2022]
Abstract
Aging of the lens is accompanied by extensive deamidation of the lens specific proteins, the crystallins. Deamidated crystallins are increased in the insoluble proteins and may contribute to cataracts. Deamidation has been shown in vitro to alter the structure and decrease the stability of human lens betaB1, betaB2 and betaA3-crystallin. Of particular interest, betaB2 mutants were constructed to mimic the effect of in vivo deamidations at the interacting interface between domains, at Q70 in the N terminal domain and at Q162, its C-terminal homologue. The double mutant was also constructed. We previously reported that deamidation at the critical interface sites decreased stability, while preserving the dimeric 3D structure. In the present study, dynamic light scattering, differential scanning calorimetry and small angle X-ray scattering were used to investigate the effect of deamidation on stability, thermal unfolding and aggregation. The bovine betaLb fraction was used for comparative analysis. The chaperone requirements of the various samples were determined using bovine alpha-crystallins as the chaperone. Deamidation at both interface Gln residues or at Q70, but not Q162, significantly lowered the temperature for unfolding and aggregation, which was rapidly followed by precipitation. This deamidation-induced aggregation and precipitation was not completely prevented by alpha-crystallin chaperone. A potential mechanism for cataract formation in vivo involving accumulation of deamidated beta-crystallin aggregates is discussed.
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Affiliation(s)
- Magalie Michiel
- Protéines, Biochimie Structurale et Fonctionnelle, CNRS-UPMC, case 29, 7 quai St Bernard, 75252 Paris Cedex 5, France
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Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res 2010; 27:544-75. [PMID: 20143256 DOI: 10.1007/s11095-009-0045-6] [Citation(s) in RCA: 732] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 12/27/2009] [Indexed: 12/16/2022]
Abstract
In 1989, Manning, Patel, and Borchardt wrote a review of protein stability (Manning et al., Pharm. Res. 6:903-918, 1989), which has been widely referenced ever since. At the time, recombinant protein therapy was still in its infancy. This review summarizes the advances that have been made since then regarding protein stabilization and formulation. In addition to a discussion of the current understanding of chemical and physical instability, sections are included on stabilization in aqueous solution and the dried state, the use of chemical modification and mutagenesis to improve stability, and the interrelationship between chemical and physical instability.
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40
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Gu Z, Ji B, Wan C, He G, Zhang J, Zhang M, Feng G, He L, Gao L. A splice site mutation in CRYBA1/A3 causing autosomal dominant posterior polar cataract in a Chinese pedigree. Mol Vis 2010; 16:154-60. [PMID: 20142846 PMCID: PMC2817011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Accepted: 02/01/2010] [Indexed: 11/04/2022] Open
Abstract
PURPOSE To identify the mutant gene for autosomal dominant posterior polar congenital cataract in a four-generation Chinese pedigree. METHODS The clinical data of patients from the family were recorded by slit-lamp photography. Genomic DNA samples from peripheral blood of the pedigree members were then isolated to map the relevant gene, using microsatellite markers for two-point linkage analysis. Genotype and haplotypes of the pedigree were constructed using Cyrillic software to locate the relevant region. Direct sequencing was performed to screen out the disease-causing mutation. RESULTS The congenital cataract phenotype of the pedigree was labeled as the posterior polar type by using slit-lamp photography. Linkage analysis results indicated a maximum logarithm of odds LOD score of (Z(max)) 2.02 at D17S1800 (theta(max)=0.00). Haplotyping identified a 26-cM region flanked by D17S921 and D17S800 on 17p12-21.2, namely at the betaA1/A3-crystallin (CRYBA1/A3) gene locus. Sequencing revealed a splice site mutation, G-->A, at the first base of intron 3 of CRYBA1/A3, which co-segregated with the affected individuals in the pedigree but which was not found in the unaffected members of the family or in the 50 unrelated controls. CONCLUSIONS Our results demonstrated that a splice site mutation of CRYBA1/A3 was responsible for the autosomal dominant posterior polar congenital cataract in a four-generation Chinese pedigree. The same mutation in this gene had previously been reported to be associated with other phenotype cataracts. This study is the first report relating a mutation of CRYBA1/A3 to posterior polar cataract.
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Affiliation(s)
- Zhensheng Gu
- Department of Ophthalmology, Xinhua Hospital, Medical College of Shanghai Jiao Tong University, Shanghai, China
| | - Baohu Ji
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Chunling Wan
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Guang He
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Juan Zhang
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Ming Zhang
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Guoyin Feng
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Lin He
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China,Institute for Nutritional Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, China,Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Linghan Gao
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
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41
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Hains PG, Truscott RJW. Age-dependent deamidation of lifelong proteins in the human lens. Invest Ophthalmol Vis Sci 2010; 51:3107-14. [PMID: 20053973 DOI: 10.1167/iovs.09-4308] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Deamidation is a common posttranslational modification in human lens crystallins and may be a key factor in the age-related denaturation of such lifelong proteins. The aim of this study was to identify the sites of deamidation in older lenses. METHODS High-performance liquid chromatography/mass spectrometry of tryptic digests was used to identify sites of deamidation in the major human lens crystallins. Older normal and age-matched cataractous lenses were compared with fetal lenses. RESULTS Approximately equal numbers of glutamine and asparagine residues were deamidated in older lenses; however, the extent of deamidation of Asn was three times greater than that of Gln (Asn, 22.6% +/- 3.6%; Gln, 6.6% +/- 1.3%). Individual crystallins differed markedly in their extent of deamidation, and deamidated residues were typically localized within discrete regions of the polypeptides. A large percentage (42%) of the sites of deamidation were characterized by the presence of a basic amino acid one residue removed from the original Gln or Asn. At nine such sites, the extent of Asn deamidation averaged 50% in aged lenses. There were few differences in deamidation between crystallins of aged normal and nuclear cataractous lenses. CONCLUSIONS Equal numbers of Asn and Gln residues are deamidated in crystallins from aged normal and cataractous lenses. Deamidation of Asn/Gln in lifelong proteins, such as those in the lens, may be governed to a significant degree by base-catalyzed processes.
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Affiliation(s)
- Peter G Hains
- Save Sight Institute, University of Sydney, Sydney, NSW, Australia
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42
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Knorre DG, Kudryashova NV, Godovikova TS. Chemical and functional aspects of posttranslational modification of proteins. Acta Naturae 2009; 1:29-51. [PMID: 22649613 PMCID: PMC3347534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This paper reviews the chemical and functional aspects of the posttranslational modifications of proteins, which are achieved by the addition of various groups to the side chain of the amino acid residue backbone of proteins. It describes the main prosthetic groups and the interaction of these groups and the apoenzyme in the process of catalysis, using pyridoxal catalysis as an example. Much attention is paid to the role of posttranslational modification of proteins in the regulation of biochemical processes in live organisms, and especially to the role of protein kinases and their respective phosphotases. Methylation and acetylation reactions and their role in the "histone code", which regulates genome expression on the transcription level, are also reviewed. This paper also describes the modification of proteins by large hydrophobic residues and their role in the function of membrane-associated proteins. Much attention is paid to the glycosylation of proteins, which leads to the formation of glycoproteins. We also describe the main non-enzymatic protein modifications such as glycation, homocysteination, and desamida-tion of amide residues in dibasic acids.
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Affiliation(s)
- D G Knorre
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences
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43
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Sharma KK, Santhoshkumar P. Lens aging: effects of crystallins. Biochim Biophys Acta Gen Subj 2009; 1790:1095-108. [PMID: 19463898 DOI: 10.1016/j.bbagen.2009.05.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 05/01/2009] [Accepted: 05/13/2009] [Indexed: 02/01/2023]
Abstract
The primary function of the eye lens is to focus light on the retina. The major proteins in the lens--alpha, beta, and gamma-crystallins--are constantly subjected to age-related changes such as oxidation, deamidation, truncation, glycation, and methylation. Such age-related modifications are cumulative and affect crystallin structure and function. With time, the modified crystallins aggregate, causing the lens to increasingly scatter light on the retina instead of focusing light on it and causing the lens to lose its transparency gradually and become opaque. Age-related lens opacity, or cataract, is the major cause of blindness worldwide. We review deamidation, and glycation that occur in the lenses during aging keeping in mind the structural and functional changes that these modifications bring about in the proteins. In addition, we review proteolysis and discuss recent observations on how crystallin fragments generated in vivo, through their anti-chaperone activity may cause crystallin aggregation in aging lenses. We also review hyperbaric oxygen treatment induced guinea pig and 'humanized' ascorbate transporting mouse models as suitable options for studies on age-related changes in lens proteins.
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Affiliation(s)
- K Krishna Sharma
- Department of Ophthalmology, University of Missouri-Columbia, 1 Hospital Drive, Columbia, MO 65212, USA.
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44
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Takata T, Woodbury LG, Lampi KJ. Deamidation alters interactions of beta-crystallins in hetero-oligomers. Mol Vis 2009; 15:241-9. [PMID: 19190732 PMCID: PMC2633459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 01/20/2009] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Cataracts are a major cause of blindness worldwide. A potential mechanism for loss of visual acuity may be due to light scattering from disruption of normal protein-protein interactions. During aging, the lens accumulates extensively deamidated crystallins. We have previously reported that deamidation in the betaA3-crystallin (betaA3) dimer decreased the stability of the dimer in vitro. The purpose of the present study was to investigate if deamidation altered the interaction of betaA3 with other beta-crystallin subunits. METHODS Deamidation was mimicked by replacing glutamines, Q85 and Q180, at the predicted interacting interface between betaA3 domains with glutamic acids by site-directed mutagenesis. Human recombinant wild type betaA3 or the doubly deamidated mutant betaA3 Q85E/Q180E (DM betaA3) were mixed with either betaB1- or betaB2-crystallin (betaB1 or betaB2) subunits. After incubation at increasing temperatures, hetero-oligomers were resolved from individual subunits and their molar masses determined by size exclusion chromatography with in line multiangle laser light scattering. Structural changes of hetero-oligomers were analyzed with fluorescence spectroscopy and blue-native PAGE. RESULTS Molar masses of the hetero-oligomer complexes indicated betaA3 formed a polydispersed hetero-tetramer with betaB1 and a mondispersed hetero-dimer with betaB2. Deamidation at the interface in the betaA3 dimer decreased formation of the hetero-oligomer with betaB1 and further decreased formation of the hetero-dimer with betaB2. During thermal-induced denaturation of the deamidated betaA3 dimer, betaB1 but not betaB2 was able to prevent precipitation of betaA3. CONCLUSIONS Deamidation decreased formation of hetero-oligomers between beta-crystallin subunits. An excess accumulation of deamidated beta-crystallins in vivo may disrupt normal protein-protein interactions and diminish the stabilizing effects between them, thus, contributing to the accumulation of insoluble beta-crystallins during aging and cataracts.
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Affiliation(s)
- Takumi Takata
- Department of Integrative Biosciences, School of Dentistry, Oregon Health & Science University, Portland, OR
| | - Luke G. Woodbury
- Department of Biological Sciences, Boise State University, Boise, ID
| | - Kirsten J. Lampi
- Department of Integrative Biosciences, School of Dentistry, Oregon Health & Science University, Portland, OR
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Takata T, Oxford JT, Demeler B, Lampi KJ. Deamidation destabilizes and triggers aggregation of a lens protein, betaA3-crystallin. Protein Sci 2008; 17:1565-75. [PMID: 18567786 DOI: 10.1110/ps.035410.108] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protein aggregation is a hallmark of several neurodegenerative diseases and also of cataracts. The major proteins in the lens of the eye are crystallins, which accumulate throughout life and are extensively modified. Deamidation is the major modification in the lens during aging and cataracts. Among the crystallins, the betaA3-subunit has been found to have multiple sites of deamidation associated with the insoluble proteins in vivo. Several sites were predicted to be exposed on the surface of betaA3 and were investigated in this study. Deamidation was mimicked by site-directed mutagenesis at Q42 and N54 on the N-terminal domain, N133 and N155 on the C-terminal domain, and N120 in the peptide connecting the domains. Deamidation altered the tertiary structure without disrupting the secondary structure or the dimer formation of betaA3. Deamidations in the C-terminal domain and in the connecting peptide decreased stability to a greater extent than deamidations in the N-terminal domain. Deamidation at N54 and N155 also disrupted the association with the betaB1-subunit. Sedimentation velocity experiments integrated with high-resolution analysis detected soluble aggregates at 15%-20% in all deamidated proteins, but not in wild-type betaA3. These aggregates had elevated frictional ratios, suggesting that they were elongated. The detection of aggregates in vitro strongly suggests that deamidation may contribute to protein aggregation in the lens. A potential mechanism may include decreased stability and/or altered interactions with other beta-subunits. Understanding the role of deamidation in the long-lived crystallins has important implications in other aggregation diseases.
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Affiliation(s)
- Takumi Takata
- Department of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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Costello MJ, Johnsen S, Metlapally S, Gilliland KO, Ramamurthy B, Krishna PV, Balasubramanian D. Ultrastructural analysis of damage to nuclear fiber cell membranes in advanced age-related cataracts from India. Exp Eye Res 2008; 87:147-58. [PMID: 18617164 DOI: 10.1016/j.exer.2008.05.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 04/24/2008] [Accepted: 05/18/2008] [Indexed: 11/25/2022]
Abstract
The primary goal was to characterize the structural alterations that occur at the fiber cell interfaces in nuclei of fully opaque cataracts removed by extracapsular cataract surgery in India. The dark yellow to brunescent nuclei, ages 38-78 years, were probably representative of advanced age-related nuclear cataracts. Thick tissue slices were fixed, en bloc stained and embedded for transmission electron microscopy. Stained thin sections contained well-preserved membranes and junctions, although the complex cellular topology often made it necessary to tilt the grid extensively to visualize the membranes. Damage to the fiber cell membranes was noted in all regions of the nucleus. The most important damage occurred within undulating membrane junctions where the loss of membrane segments was common. These membrane breaks were not sites of fusion as membrane edges were detected and cytoplasm appeared to be in contact with extracellular space, which was enlarged in many regions. Dense deposits of protein-like material were frequently observed within the extracellular space and appeared to be similar to protein in the adjacent cytoplasm. The deposits were often 20-50 nm thick, variable in length and located on specific sites on plasma membranes and between clusters of cells or cell processes. In addition, low density regions were seen within the extracellular space, especially within highly undulating membranes where spaces about 100 nm in diameter were observed. The membrane damage was more extensive and extracellular spaces were larger than in aged transparent donor lenses. Because high and low density regions contribute equally to the fluctuations in refractive index, the changes in density due to the observed damage near membranes are likely to produce significant light scattering based on theoretical analysis. The dimensions of the fluctuations in the range 20-100 nm imply that the scattering is probably similar to that of small particles that would increase high-angle scattering visible in the slit lamp. Such damage to membranes would be expected to contribute to the total opacification of the nucleus as the cataract matures. The main sources of the fluctuations appear to be the degradation of membranes and adjacent cytoplasmic proteins, as well as the redistribution of proteins and fragments.
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Affiliation(s)
- M J Costello
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7090, USA.
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47
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Mafia K, Gupta R, Kirk M, Wilson L, Srivastava OP, Barnes S. UV-A-induced structural and functional changes in human lens deamidated alphaB-crystallin. Mol Vis 2008; 14:234-48. [PMID: 18334940 PMCID: PMC2255029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 01/22/2008] [Indexed: 12/01/2022] Open
Abstract
PURPOSE To determine comparative effects of ultraviolet (UV)-A irradiation on structural and functional properties of wild type (WT) alphaB-crystallin and its three deamidated mutant proteins (alphaB-Asn78Asp, alphaB-Asn146Asp, and alphaB-Asn78/146Asp). METHODS Three deamidated mutants previously generated from recombinant WT alphaB-crystallin, using a site-specific mutagenesis procedure as previously described [32], were used. The WT alphaB-crystallin and its three deamidated species were exposed to UV-A light (320-400 nm) at intensities of 20 or 50 J/cm(2). The UV-A-unexposed and UV-A-exposed preparations were examined for their chaperone activity, and their activities were correlated with the UV-A-induced structural changes. The structural properties studied included dimerization and degradation, intrinsic tryptophan (Trp) fluorescence, ANS (8-anilino-1-naphthalenesulfate)-binding, far ultraviolet circular dichroism (UV-CD) spectral analysis, molecular sizes by dynamic light scattering, and oxidation of Trp and methionine (Met) residues. RESULTS The WT alphaB-crystallin and its three deamidated mutant proteins showed enhanced dimerization to 40 kDa species and partial degradation with increasing doses during UV-A-exposure. Compared to the deamidation of asparagines (Asn) 78 residue to aspartic acid (Asp) or both Asn78 and Asn146 residues to Asp, the deamidation of Asn146 residue to Asp resulted in a greater loss of chaperone activity. The UV-A-induced loss of chaperone activity due to structural changes was studied. The ANS-binding data suggested that the alphaB-Asn146Asp mutant protein had a relatively compact structure and an increase in surface hydrophobic patches compared to WT and two other deamidated proteins. Similarly, UV-A-exposure altered the Trp microenvironment in the deamidated mutant proteins compared to the WT alphaB-crystallin. Far-UV CD spectral analyses showed almost no changes among WT and deamidated species on UV-A-exposure except that the alphaB-Asn146Asp mutant protein showed maximum changes in the random coil structure relative to WT alphaB-crystallin and two other deamidated proteins. The UV-A-exposure also resulted in the aggregation of WT and the three deamidated mutant proteins with species of greater mass compared to the non-UV-A exposed species. Among the four spots recovered after two-dimensional (2D)-gel electrophoresis from WT and the three deamidated species, the Met and Trp residues of alphaB-Asn146Asp mutant showed maximum oxidation after UV-A exposure, which might account for its greater loss in chaperone activity compared to WT alphaB-crystallin and two other deamidated species. CONCLUSIONS After UV-A-exposure, the deamidated alphaB-Asn146Asp mutant protein showed a complete loss of chaperone activity compared to WT alphaB and alphaB-Asn78Asp and alphaB-Asn78/146Asp deamidated species. Apparently, this loss of chaperone activity was due to oxidative changes leading to its greater structural alteration compared to other alphaB-species.
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Affiliation(s)
- Kerri Mafia
- Department of Pharmacology, University of Alabama at Birmingham, Birmingham, AL 35226, USA
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Mills IA, Flaugh SL, Kosinski-Collins MS, King JA. Folding and stability of the isolated Greek key domains of the long-lived human lens proteins gammaD-crystallin and gammaS-crystallin. Protein Sci 2007; 16:2427-44. [PMID: 17905830 PMCID: PMC2211709 DOI: 10.1110/ps.072970207] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The transparency of the eye lens depends on the high solubility and stability of the lens crystallin proteins. The monomeric gamma-crystallins and oligomeric beta-crystallins have paired homologous double Greek key domains, presumably evolved through gene duplication and fusion. Prior investigation of the refolding of human gammaD-crystallin revealed that the C-terminal domain folds first and nucleates the folding of the N-terminal domain. This result suggested that the human N-terminal domain might not be able to fold on its own. We constructed and expressed polypeptide chains corresponding to the isolated N- and C-terminal domains of human gammaD-crystallin, as well as the isolated domains of human gammaS-crystallin. Both circular dichroism and fluorescence spectroscopy indicated that the isolated domains purified from Escherichia coli were folded into native-like monomers. After denaturation, the isolated domains refolded efficiently at pH 7 and 37 degrees C into native-like structures. The in vitro refolding of all four domains revealed two kinetic phases, identifying partially folded intermediates for the Greek key motifs. When subjected to thermal denaturation, the isolated N-terminal domains were less stable than the full-length proteins and less stable than the C-terminal domains, and this was confirmed in equilibrium unfolding/refolding experiments. The decrease in stability of the N-terminal domain of human gammaD-crystallin with respect to the complete protein indicated that the interdomain interface contributes of 4.2 kcal/mol to the overall stability of this very long-lived protein.
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Affiliation(s)
- Ishara A Mills
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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