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Santhoshkumar P, Sharma KK. Substrate Protein Interactions and Methylglyoxal Modifications Reduce the Aggregation Propensity of Human Alpha-A-Crystallin G98R Mutant. Front Mol Biosci 2022; 9:875205. [PMID: 35463950 PMCID: PMC9019814 DOI: 10.3389/fmolb.2022.875205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 03/22/2022] [Indexed: 11/17/2022] Open
Abstract
The G98R mutation in αA-crystallin is associated with presenile cataract development in humans. Previous studies have indicated that mutant proteins altered structure, decreased stability, increased oligomeric size, loss of chaperone-like activity, and susceptibility to proteolysis could be contributing factors to cataract formation. To evaluate the effect of substrate protein interactions with the mutant protein on cataract formation, we have performed chaperone assays with alcohol dehydrogenase (ADH), citrate synthase (CS), and βB2-crystallin (βB2), and analyzed the reaction mixtures by multi-angle light scattering (MALS) analysis. It appears that αAG98R protein initially gets stabilized upon interaction with substrate proteins. Analysis of the chaperone-client protein complexes revealed that wild-type αA-crystallin interacts with substrate proteins to form compact complexes leading to a slight increase in oligomeric mass, whereas αAG98R forms less compact and high molecular weight complexes with the substrate, and the resulting complexes continue to increase in size over time. As a result, the soluble complexes formed initially by the mutant protein begin to scatter light and precipitate. We found that the stability and chaperone activity of the αAG98R can be improved by modifying the protein with low concentrations (50 µM) of methylglyoxal (MGO). Incubation of αAG98R protein (1 mg/ml) under aseptic conditions for 30 days at 37°C resulted in precipitation of the mutant protein. In contrast, mutant protein incubations carried out with 50 µM MGO remained soluble and transparent. SDS-PAGE analysis showed gradual autolysis of the mutant protein in the absence of MGO. The average molar mass of the mutant protein oligomers changed from 7,258 ± 12 kDa to 3,950 ± 08 kDa within 60 min of incubation with MGO. There was no further significant change in the molar mass of mutant protein when tested on day 7 of MGO treatment. Our data suggest that the initial stabilization of αAG98R by substrate proteins could delay congenital cataracts' appearance, and the uncontrolled long-term interaction amongst mutant subunits and substrate proteins could be the rationale behind presenile cataracts formation. The results also demonstrate the potential benefit of low concentrations of MGO in stabilizing mutant chaperone protein(s).
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Affiliation(s)
- Puttur Santhoshkumar
- Department of Ophthalmology, University of Missouri, Columbia, MO, United States
| | - Krishna K. Sharma
- Department of Ophthalmology, University of Missouri, Columbia, MO, United States
- Department of Biochemistry, University of Missouri, Columbia, MO, United States
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Santhoshkumar P, Karmakar S, Sharma KK. Structural and functional consequences of chaperone site deletion in αA-crystallin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1529-38. [PMID: 27524665 DOI: 10.1016/j.bbapap.2016.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/05/2016] [Accepted: 08/09/2016] [Indexed: 01/29/2023]
Abstract
The chaperone-like activity of αA-crystallin has an important role in maintaining lens transparency. Previously we identified residues 70-88 as a chaperone site in αA-crystallin. In this study, we deleted the chaperone site residues to generate αAΔ70-76 and αAΔ70-88 mutants and investigated if there are additional substrate-binding sites in αA-crystallin. Both mutant proteins when expressed in E. coli formed inclusion bodies, and on solubilizing and refolding, they exhibited similar structural properties, with a 2- to 3-fold increase in molar mass compared to the molar mass of wild-type protein. The deletion mutants were less stable than the wild-type αA-crystallin. Functionally αAΔ70-88 was completely inactive as a chaperone, while αAΔ70-76 demonstrated a 40-50% reduction in anti-aggregation activity against alcohol dehydrogenase (ADH). Deletion of residues 70-88 abolished the ADH binding sites in αA-crystallin at physiological temperature. At 45°C, cryptic ADH binding site(s) became exposed, which contributed subtly to the chaperone-like activity of αAΔ70-88. Both of the deletion mutants were completely inactive in suppressing aggregation of βL-crystallin at 53°C. The mutants completely lost the anti-apoptotic property that αA-crystallin exhibits while they protected ARPE-19 (a human retinal pigment epithelial cell line) and primary human primary lens epithelial (HLE) cells from oxidative stress. Our studies demonstrate that residues 70-88 in αA-crystallin act as a primary substrate binding site and account for the bulk of the total chaperone activity. The β3 and β4 strands in αA-crystallin comprising 70-88 residues play an important role in maintenance of the structure and in preventing aggregation of denaturing proteins.
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Affiliation(s)
- Puttur Santhoshkumar
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, United States.
| | - Srabani Karmakar
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, United States
| | - Krishna K Sharma
- Department of Ophthalmology, University of Missouri School of Medicine, Columbia, MO 65212, United States; Department of Biochemistry, University of Missouri School of Medicine, Columbia, MO 65212, United States.
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Nandi SK, Rehna EAA, Panda AK, Shiburaj S, Dharmalingam K, Biswas A. A S52P mutation in the ‘α-crystallin domain’ ofMycobacterium lepraeHSP18 reduces its oligomeric size and chaperone function. FEBS J 2013; 280:5994-6009. [DOI: 10.1111/febs.12519] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/28/2013] [Accepted: 09/04/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Sandip K. Nandi
- School of Basic Sciences; Indian Institute of Technology Bhubaneswar; Orissa India
| | - Elengikal A. A. Rehna
- Department of Genetic Engineering; School of Biotechnology; Madurai Kamraj University; Tamilnadu India
| | - Alok K. Panda
- School of Basic Sciences; Indian Institute of Technology Bhubaneswar; Orissa India
| | - Sugathan Shiburaj
- Jawaharlal Nehru Tropical Botanic Garden and Research Institute; Palode Thiruvananthapuram Kerala India
| | - Kuppamuthu Dharmalingam
- Department of Genetic Engineering; School of Biotechnology; Madurai Kamraj University; Tamilnadu India
| | - Ashis Biswas
- School of Basic Sciences; Indian Institute of Technology Bhubaneswar; Orissa India
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Kannan R, Santhoshkumar P, Mooney BP, Sharma KK. Identification of subunit-subunit interaction sites in αA-WT crystallin and mutant αA-G98R crystallin using isotope-labeled cross-linker and mass spectrometry. PLoS One 2013; 8:e65610. [PMID: 23755258 PMCID: PMC3673982 DOI: 10.1371/journal.pone.0065610] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 04/30/2013] [Indexed: 12/03/2022] Open
Abstract
Cataract is characterized by progressive protein aggregation and loss of vision. α-Crystallins are the major proteins in the lens responsible for maintaining transparency. They exist in the lens as highly polydisperse oligomers with variable numbers of subunits, and mutations in α-crystallin are associated with some forms of cataract in humans. Because the stability of proteins is dependent on optimal subunit interactions, the structural transformations and aggregation of mutant proteins that underlie cataract formation can be understood best by identifying the residue-specific inter- and intra-subunit interactions. Chemical crosslinking combined with mass spectrometry is increasingly used to provide structural insights into intra- and inter-protein interactions. We used isotope-labeled cross-linker in combination with LC-MS/MS to determine the subunit–subunit interaction sites in cataract-causing mutant αA-G98R crystallin. Peptides cross-linked by isotope-labeled (heavy and light forms) cross-linkers appear as doublets in mass spectra, thus facilitating the identification of cross-linker–containing peptides. In this study, we cross-linked wild-type (αA-WT) and mutant (αA-G98R) crystallins using the homobifunctional amine-reactive, isotope-labeled (d0 and d4) cross-linker–BS2G (bis[sulfosuccinimidyl]glutarate). Tryptic in-solution digest of cross-linked complexes generates a wide array of peptide mixtures. Cross-linked peptides were enriched using strong cation exchange (SCX) chromatography followed by both MS and MS/MS to identify the cross-linked sites. We identified a distinct intermolecular interaction site between K88 — K99 in the β5 strand of the mutant αA-G98R crystallin that is not found in wild-type αA-crystallin. This interaction could explain the conformational instability and aggregation nature of the mutant protein that results from incorrect folding and assembly.
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Affiliation(s)
- Rama Kannan
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
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Clark AR, Lubsen NH, Slingsby C. sHSP in the eye lens: Crystallin mutations, cataract and proteostasis. Int J Biochem Cell Biol 2012; 44:1687-97. [DOI: 10.1016/j.biocel.2012.02.015] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/23/2012] [Indexed: 01/25/2023]
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Raju I, Oonthonpan L, Abraham EC. Mutations in human αA-crystallin/sHSP affect subunit exchange interaction with αB-crystallin. PLoS One 2012; 7:e31421. [PMID: 22347476 PMCID: PMC3275625 DOI: 10.1371/journal.pone.0031421] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/07/2012] [Indexed: 11/18/2022] Open
Abstract
Background Mutation in αA-crystallin contributes to the development of congenital cataract in humans. Heterooligomerization of αA-crystallin and αB-crystallin is essential for maintaining transparency in the eye lens. The effect of congenital cataract causing mutants of αA-crystallin on subunit exchange and interaction with αB-crystallin is unknown. In the present study, interaction of the mutants of αA-crystallin with αB-crystallin was studied both in vitro and in situ by the fluorescence resonance energy transfer (FRET) technique. Methodology/Principal Findings In vitro FRET technique was used to demonstrate the rates of subunit exchange of αB-wt with the following αA-crystallin mutants: R12C, R21L, R21W, R49C, R54C, and R116C. The subunit exchange rates (k values) of R21W and R116C with αB-wt decreased drastically as compared to αA-wt interacting with αB-wt. Moderately decreased k values were seen with R12C, R49C and R54C while R21L showed nearly normal k value. The interaction of αA- mutants with αB-wt was also assessed by in situ FRET. YFP-tagged αA mutants were co-expressed with CFP-tagged αB-wt in HeLa cells and the spectral signals were captured with a confocal microscope before and after acceptor laser photobleaching. The interaction of R21W and R116C with αB-wt was decreased nearly 50% as compared to αA-wt while the rest of the mutants showed slightly decreased interaction. Thus, there is good agreement between the in vitro and in situ FRET data. Conclusions/Significance Structural changes occurring in these mutants, as reported earlier, could be the underlying cause for the decreased interaction with αB may contribute to development of congenital cataract.
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Affiliation(s)
- Ilangovan Raju
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Lalita Oonthonpan
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Edathara C. Abraham
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
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Validandi V, Reddy VS, Srinivas PNBS, Mueller NH, Bhagyalaxmi SG, Padma T, Petrash JM, Reddy GB. Temperature-dependent structural and functional properties of a mutant (F71L) αA-crystallin: molecular basis for early onset of age-related cataract. FEBS Lett 2011; 585:3884-9. [PMID: 22085609 DOI: 10.1016/j.febslet.2011.10.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 10/15/2011] [Accepted: 10/25/2011] [Indexed: 11/20/2022]
Abstract
Previously we identified a novel mutation (F71L) in the αA-crystallin gene associated with early onset of age-related cataract. However, it is not known how the missense substitution translates into reduced chaperone-like activity (CLA), and how the structural and functional changes lead to early onset of the disease. Herein, we show that under native conditions the F71L-mutant is not significantly different from wild-type with regard to secondary and tertiary structural organization, hydrophobicity and the apparent molecular mass of oligomer but has substantial differences in structural and functional properties following a heat treatment. Wild-type αA-crystallin demonstrated increased CLA, whereas the F71L-mutant substantially lost its CLA upon heat treatment. Further, unlike the wild-type αA-subunit, F71L-subunit did not protect the αB-subunit in hetero-oligomeric complex from heat-induced aggregation. Moreover, hetero-oligomer containing F71L and αB in 3:1 ratio had significantly lower CLA upon thermal treatment compared to its unheated control. These results indicate that α-crystallin complexes containing F71L-αA subunits are less stable and have reduced CLA. Therefore, F71L may lead to earlier onset of cataract due to interaction with several environmental factors (e.g., temperature in this case) along with the aging process.
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Affiliation(s)
- Vakdevi Validandi
- Biochemistry Division, National Institute of Nutrition, Hyderabad, India
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Huang B, He W. Molecular characteristics of inherited congenital cataracts. Eur J Med Genet 2010; 53:347-57. [PMID: 20624502 DOI: 10.1016/j.ejmg.2010.07.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Accepted: 07/04/2010] [Indexed: 01/20/2023]
Abstract
Congenital cataracts are a major cause of induced blindness in children, and inherited cataracts are the major cause of congenital cataracts. Inherited congenital cataracts have been associated with mutations in specific genes, including those of crystallins, gap junction proteins, membrane transport and channel proteins, the cytoskeleton, and growth and transcription factors. Locating and identifying the genes and mutations involved in cataractogenesis are essential to gaining an understanding of the molecular defects and pathophysiologic characteristics of inherited congenital cataracts. In this review, we summarize the current research in this field.
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Affiliation(s)
- Bingyu Huang
- Medical Genetics Laboratory, Department of Obstetrics and Gynecology, Second Teaching Hospital, Jilin University, 218 Zhiqiang, Changchun, 130041, China.
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Pang M, Su JT, Feng S, Tang ZW, Gu F, Zhang M, Ma X, Yan YB. Effects of congenital cataract mutation R116H on αA-crystallin structure, function and stability. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:948-56. [PMID: 20079887 DOI: 10.1016/j.bbapap.2010.01.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 12/11/2009] [Accepted: 01/07/2010] [Indexed: 10/20/2022]
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de Groot NS, Sabate R, Ventura S. Amyloids in bacterial inclusion bodies. Trends Biochem Sci 2009; 34:408-16. [DOI: 10.1016/j.tibs.2009.03.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 03/31/2009] [Accepted: 03/31/2009] [Indexed: 10/20/2022]
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Andley UP. AlphaA-crystallin R49Cneo mutation influences the architecture of lens fiber cell membranes and causes posterior and nuclear cataracts in mice. BMC Ophthalmol 2009; 9:4. [PMID: 19619312 PMCID: PMC2724435 DOI: 10.1186/1471-2415-9-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 07/20/2009] [Indexed: 01/20/2023] Open
Abstract
Background αA-crystallin (CRYAA/HSPB4), a major component of all vertebrate eye lenses, is a small heat shock protein responsible for maintaining lens transparency. The R49C mutation in the αA-crystallin protein is linked with non-syndromic, hereditary human cataracts in a four-generation Caucasian family. Methods This study describes a mouse cataract model generated by insertion of a neomycin-resistant (neor) gene into an intron of the gene encoding mutant R49C αA-crystallin. Mice carrying the neor gene and wild-type Cryaa were also generated as controls. Heterozygous knock-in mice containing one wild type gene and one mutated gene for αA-crystallin (WT/R49Cneo) and homozygous knock-in mice containing two mutated genes (R49Cneo/R49Cneo) were compared. Results By 3 weeks, WT/R49Cneo mice exhibited large vacuoles in the cortical region 100 μm from the lens surface, and by 3 months posterior and nuclear cataracts had developed. WT/R49Cneo mice demonstrated severe posterior cataracts at 9 months of age, with considerable posterior nuclear migration evident in histological sections. R49Cneo/R49Cneo mice demonstrated nearly complete lens opacities by 5 months of age. In contrast, R49C mice in which the neor gene was deleted by breeding with CreEIIa mice developed lens abnormalities at birth, suggesting that the neor gene may suppress expression of mutant R49C αA-crystallin protein. Conclusion It is apparent that modification of membrane and cell-cell interactions occurs in the presence of the αA-crystallin mutation and rapidly leads to lens cell pathology in vivo.
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Affiliation(s)
- Usha P Andley
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, Missouri, USA.
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de Groot NS, Espargaró A, Morell M, Ventura S. Studies on bacterial inclusion bodies. Future Microbiol 2008; 3:423-35. [DOI: 10.2217/17460913.3.4.423] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The field of protein misfolding and aggregation has become an extremely active area of research in recent years. Of particular interest is the deposition of polypeptides into inclusion bodies inside bacterial cells. One reason for this interest is that protein aggregation constitutes a major bottleneck in protein production and restricts the spectrum of protein-based drugs available for commercialization. Additionally, prokaryotic cells could provide a simple yet powerful system for studying the formation and prevention of toxic aggregates, such as those responsible for a number of degenerative diseases. Here, we review recent work that has challenged our understanding of the structure and physiology of inclusion bodies and provided us with a new view of intracellular protein deposition, which has important implications in microbiology, biomedicine and biotechnology.
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Affiliation(s)
- Natalia S de Groot
- Departament de Bioquímica i Biologia Molecular & Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Alba Espargaró
- Departament de Bioquímica i Biologia Molecular & Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Montserrat Morell
- Departament de Bioquímica i Biologia Molecular & Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Salvador Ventura
- Departament de Bioquímica i Biologia Molecular & Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
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