1
|
Goswami V, Das SM, Deep S. Quercetin-Loaded Nanocarriers as Effective Inhibitors for Copper Metal Ion-Induced γD-Crystallin Aggregation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:16093-16102. [PMID: 39046313 DOI: 10.1021/acs.langmuir.4c00933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Cataract is one of the leading causes of blindness worldwide. Till date, the only solution for cataracts is surgery, which is a resource-intensive solution. A much simpler solution is to find a potential drug that could inhibit aggregation. It is well established that nonamyloid aggregates of eye lens protein result in cataract. γD-Crystallin, a thermodynamically stable protein, is one of the most abundant proteins in the core of the eye lens and is found to aggregate under stress conditions, leading to the cataract. It has also been found that in cataractous lens, the concentration of metals like copper is elevated significantly as compared to healthy eye lens, suggesting their role in inducing aggregation. In our present study, aggregation of γD-Crystallin was carried out in the presence of Cu (II). Using techniques like turbidity assay, CD spectroscopy, ANS binding assay, and microscopic studies like TEM, it could be confirmed that protein aggregates in the presence of Cu (II) and the nature of aggregates is amorphous. Various polyphenols were tested to suppress aggregation of the protein. Quercetin was observed to be the most efficient. To overcome the problems associated with the delivery of polyphenols, such as solubility and bioavailability, quercetin was encapsulated in two types of nanocarriers. Their characterization was done using TEM, DLS, and other techniques. The potency of quercetin-loaded CS-TPP/CS-PLGA NPs as inhibitors of γD-Crystallin aggregation was confirmed by various experiments.
Collapse
Affiliation(s)
- Vishakha Goswami
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sony Moni Das
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shashank Deep
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| |
Collapse
|
2
|
Guseman AJ, González JJ, Yang D, Gronenborn AM. Cumulative asparagine to aspartate deamidation fails to perturb γD-crystallin structure and stability. Protein Sci 2024; 33:e5120. [PMID: 39022918 PMCID: PMC11255865 DOI: 10.1002/pro.5120] [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: 01/30/2024] [Revised: 06/05/2024] [Accepted: 07/07/2024] [Indexed: 07/20/2024]
Abstract
Deamidation frequently is invoked as an important driver of crystallin aggregation and cataract formation. Here, we characterized the structural and biophysical consequences of cumulative Asn to Asp changes in γD-crystallin. Using NMR spectroscopy, we demonstrate that N- or C-terminal domain-confined or fully Asn to Asp changed γD-crystallin exhibits essentially the same 1H-15N HSQC spectrum as the wild-type protein, implying that the overall structure is retained. Only a very small thermodynamic destabilization for the overall Asn to Asp γD-crystallin variants was noted by chaotropic unfolding, and assessment of the colloidal stability, by measuring diffusion interaction parameters, yielded no substantive differences in association propensities. Furthermore, using molecular dynamics simulations, no significant changes in dynamics for proteins with Asn to Asp or iso-Asp changes were detected. Our combined results demonstrate that substitution of all Asn by Asp residues, reflecting an extreme case of deamidation, did not affect the structure and biophysical properties of γD-crystallin. This suggests that these changes alone cannot be the major determinant in driving cataract formation.
Collapse
Affiliation(s)
- Alex J. Guseman
- Department of Structural BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Jeremy J. González
- Department of Structural BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Darian Yang
- Department of Structural BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Angela M. Gronenborn
- Department of Structural BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| |
Collapse
|
3
|
Ghosh D, Biswas A, Radhakrishna M. Advanced computational approaches to understand protein aggregation. BIOPHYSICS REVIEWS 2024; 5:021302. [PMID: 38681860 PMCID: PMC11045254 DOI: 10.1063/5.0180691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 03/18/2024] [Indexed: 05/01/2024]
Abstract
Protein aggregation is a widespread phenomenon implicated in debilitating diseases like Alzheimer's, Parkinson's, and cataracts, presenting complex hurdles for the field of molecular biology. In this review, we explore the evolving realm of computational methods and bioinformatics tools that have revolutionized our comprehension of protein aggregation. Beginning with a discussion of the multifaceted challenges associated with understanding this process and emphasizing the critical need for precise predictive tools, we highlight how computational techniques have become indispensable for understanding protein aggregation. We focus on molecular simulations, notably molecular dynamics (MD) simulations, spanning from atomistic to coarse-grained levels, which have emerged as pivotal tools in unraveling the complex dynamics governing protein aggregation in diseases such as cataracts, Alzheimer's, and Parkinson's. MD simulations provide microscopic insights into protein interactions and the subtleties of aggregation pathways, with advanced techniques like replica exchange molecular dynamics, Metadynamics (MetaD), and umbrella sampling enhancing our understanding by probing intricate energy landscapes and transition states. We delve into specific applications of MD simulations, elucidating the chaperone mechanism underlying cataract formation using Markov state modeling and the intricate pathways and interactions driving the toxic aggregate formation in Alzheimer's and Parkinson's disease. Transitioning we highlight how computational techniques, including bioinformatics, sequence analysis, structural data, machine learning algorithms, and artificial intelligence have become indispensable for predicting protein aggregation propensity and locating aggregation-prone regions within protein sequences. Throughout our exploration, we underscore the symbiotic relationship between computational approaches and empirical data, which has paved the way for potential therapeutic strategies against protein aggregation-related diseases. In conclusion, this review offers a comprehensive overview of advanced computational methodologies and bioinformatics tools that have catalyzed breakthroughs in unraveling the molecular basis of protein aggregation, with significant implications for clinical interventions, standing at the intersection of computational biology and experimental research.
Collapse
Affiliation(s)
- Deepshikha Ghosh
- Department of Biological Sciences and Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat 382355, India
| | - Anushka Biswas
- Department of Chemical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat 382355, India
| | | |
Collapse
|
4
|
Kacirani A, Uralcan B, Domingues TS, Haji-Akbari A. Effect of Pressure on the Conformational Landscape of Human γD-Crystallin from Replica Exchange Molecular Dynamics Simulations. J Phys Chem B 2024; 128:4931-4942. [PMID: 38685567 DOI: 10.1021/acs.jpcb.4c00178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Human γD-crystallin belongs to a crucial family of proteins known as crystallins located in the fiber cells of the human lens. Since crystallins do not undergo any turnover after birth, they need to possess remarkable thermodynamic stability. However, their sporadic misfolding and aggregation, triggered by environmental perturbations or genetic mutations, constitute the molecular basis of cataracts, which is the primary cause of blindness in the globe according to the World Health Organization. Here, we investigate the impact of high pressure on the conformational landscape of wild-type HγD-crystallin using replica exchange molecular dynamics simulations augmented with principal component analysis. We find pressure to have a modest impact on global measures of protein stability, such as root-mean-square displacement and radius of gyration. Upon projecting our trajectories along the first two principal components from principal component analysis, however, we observe the emergence of distinct free energy basins at high pressures. By screening local order parameters previously shown or hypothesized as markers of HγD-crystallin stability, we establish correlations between a tyrosine-tyrosine aromatic contact within the N-terminal domain and the protein's end-to-end distance with projections along the first and second principal components, respectively. Furthermore, we observe the simultaneous contraction of the hydrophobic core and its intrusion by water molecules. This exploration sheds light on the intricate responses of HγD-crystallin to elevated pressures, offering insights into potential mechanisms underlying its stability and susceptibility to environmental perturbations, crucial for understanding cataract formation.
Collapse
Affiliation(s)
- Arlind Kacirani
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, United States
| | - Betül Uralcan
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
- Department of Chemical Engineering, Boğaziçi University, Istanbul 34342, Turkey
| | - Tiago S Domingues
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
- Graduate Program in Applied Mathematics, Yale University, New Haven, Connecticut 06520, United States
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Hill JA, Nyathi Y, Horrell S, von Stetten D, Axford D, Owen RL, Beddard GS, Pearson AR, Ginn HM, Yorke BA. An ultraviolet-driven rescue pathway for oxidative stress to eye lens protein human gamma-D crystallin. Commun Chem 2024; 7:81. [PMID: 38600176 PMCID: PMC11006947 DOI: 10.1038/s42004-024-01163-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/27/2024] [Indexed: 04/12/2024] Open
Abstract
Human gamma-D crystallin (HGD) is a major constituent of the eye lens. Aggregation of HGD contributes to cataract formation, the leading cause of blindness worldwide. It is unique in its longevity, maintaining its folded and soluble state for 50-60 years. One outstanding question is the structural basis of this longevity despite oxidative aging and environmental stressors including ultraviolet radiation (UV). Here we present crystallographic structures evidencing a UV-induced crystallin redox switch mechanism. The room-temperature serial synchrotron crystallographic (SSX) structure of freshly prepared crystallin mutant (R36S) shows no post-translational modifications. After aging for nine months in the absence of light, a thiol-adduct (dithiothreitol) modifying surface cysteines is observed by low-dose SSX. This is shown to be UV-labile in an acutely light-exposed structure. This suggests a mechanism by which a major source of crystallin damage, UV, may also act as a rescuing factor in a finely balanced redox system.
Collapse
Affiliation(s)
- Jake A Hill
- School of Chemistry and Biosciences, University of Bradford, Richmond Road, Bradford, BD7 1DP, United Kingdom
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Yvonne Nyathi
- Faculty of Biological Sciences, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
| | - Sam Horrell
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - David von Stetten
- European Molecular Biology Laboratory, Notkestraße 85, 22607, Hamburg, Germany
| | - Danny Axford
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Robin L Owen
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Godfrey S Beddard
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh, EH9 3FJ, United Kingdom
| | - Arwen R Pearson
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany
| | - Helen M Ginn
- HARBOR, Institute for Nanostructure and Solid State Physics, Hamburg, 22761, Germany.
- Center for Free-Electron Laser Science, CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
| | - Briony A Yorke
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom.
| |
Collapse
|
7
|
Boateng AK, Joseph R, Srivastava OP. Dysregulation of Autophagy Occurs During Congenital Cataract Development in βA3ΔG91 Mice. Invest Ophthalmol Vis Sci 2024; 65:4. [PMID: 38558092 PMCID: PMC10996937 DOI: 10.1167/iovs.65.4.4] [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: 07/25/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
Purpose To examine lens phenotypic characteristics in βA3ΔG91 mice and determine if βA3ΔG91 affects autophagy in the lens. Methods We generated a βA3ΔG91 mouse model using CRISPR/Cas9 methodology. Comparative phenotypic and biochemical characterizations of lenses from postnatal day 0 (P0), P15, and 1-month-old βA3ΔG91 and wild-type (WT) mice were performed. The methodologies used included non-invasive slit-lamp examination, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot, and immunohistochemical (IHC) analyses to determine the levels of autophagy-related genes and proteins. Transmission electron microscopy (TEM) analysis of lenses was performed to assess organelle degradation and the presence of autophagic vesicles. TUNEL staining was used to determine apoptosis in the lens. Results Relative to WT lenses, 1-month-old βA3ΔG91 mice developed congenital nuclear cataract and microphthalmia and showed an early loss of endoplasmic reticulum (ER) in the cortex and attenuation of nuclei degradation. This observation was confirmed by TEM analysis, as was the presence of autophagic vesicles in βA3ΔG91 lenses. Comparative IHC and RT-qPCR analyses showed relatively higher levels of autophagy markers (ubiquitinated proteins and p62, LC3, and LAMP2 proteins) in βA3ΔG91 lenses compared to WT lenses. Additionally, βA3ΔG91 lenses showed relatively greater numbers of apoptotic cells and higher levels of cleaved caspase-3 and caspase-9. Conclusions The deletion of G91 in βA3ΔG91 mice leads to higher levels of expression of autophagy-related proteins and their transcripts relative to WT lenses. Taken together, G91 deletion in βA3/A1-crystallin is associated with autophagy disruption, attenuation of nuclei degradation, and cellular apoptosis in the lens, which might be congenital cataract causative factors.
Collapse
Affiliation(s)
- Akosua K. Boateng
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Roy Joseph
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Om P. Srivastava
- Department of Optometry and Vision Science, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| |
Collapse
|
8
|
Ghosh D, Agarwal M, Radhakrishna M. Molecular Insights into the Inhibitory Role of α-Crystallin against γD-Crystallin Aggregation. J Chem Theory Comput 2024; 20:1740-1752. [PMID: 38078935 DOI: 10.1021/acs.jctc.3c00774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Cataracts, a major cause of global blindness, contribute significantly to the overall prevalence of blindness. The opacification of the lens, resulting in cataract formation, primarily occurs due to the aggregation of crystallin proteins within the eye lens. Despite the high concentration of these crystallins, they remarkably maintain the lens transparency and refractive index. α-Crystallins (α-crys), acting as chaperones, play a crucial role in preventing crystallin aggregation, although the exact molecular mechanism remains uncertain. In this study, we employed a combination of molecular docking, all-atom molecular dynamics simulations, and advanced free energy calculations to investigate the interaction between γD-crystallin (γD-crys), a major structural protein of the eye lens, and α-crystallin proteins. Our findings demonstrate that α-crys exhibits an enhanced affinity for the NTD2 and CTD4 regions of γD-crys. The NTD2 and CTD4 regions form the interface between the N-terminal domain (NTD) and the C-terminal domain (CTD) of the γD-crys protein. By binding to the interface region between the NTD and CTD of the protein, α-crys effectively inhibits the formation of domain-swapped aggregates and mitigates protein aggregation. Analysis of the Markov state models using molecular dynamics trajectories confirms that minimum free energy conformations correspond to the binding of the α-crystallin domain (ACD) of α-crys to NTD2 and CTD4 that form the interdomain interface.
Collapse
Affiliation(s)
- Deepshikha Ghosh
- Department of Biological Sciences and Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat 382355, India
| | - Manish Agarwal
- Computer Services Centre, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, Delhi 110016, India
| | - Mithun Radhakrishna
- Department of Chemical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat 382355, India
- Center for Biomedical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat 382355, India
| |
Collapse
|
9
|
Lin N, Zhang Y, Song X, Xu J, Luo C, Tian Q, Yao K, Wu W, Chen X, Hu L. Cataract-causing mutations S78F and S78P of γD-crystallin decrease protein conformational stability and drive aggregation. Int J Biol Macromol 2023; 253:126910. [PMID: 37739288 DOI: 10.1016/j.ijbiomac.2023.126910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/28/2023] [Accepted: 09/13/2023] [Indexed: 09/24/2023]
Abstract
Congenital cataract is the leading cause of childhood blindness, which primarily results from genetic factors. γD-crystallin is the most abundant γ-crystallin and is essential for maintaining lens transparency and refractivity. Numerous mutations in γD-crystallin have been reported with unclear pathogenic mechanism. Two different cataract-causing mutations Ser78Phe and Ser78Pro in γD-crystallin were previously identified at the same conserved Ser78 residue. In this work, firstly, we purified the mutants and characterized for the structural change using fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and size-exclusion chromatography (SEC). Both mutants were prone to form insoluble precipitates when expressed in Escherichia coli strain BL21 (DE3) cells. Compared with wild-type (WT), both mutations caused structural disruption, increased hydrophobic exposure, decreased solubility, and reduced thermal stability. Next, we investigated the aggregation of the mutants at the cellular level. Overexpression the mutants in HLE-B3 and HEK 293T cells could induce aggresome formations. The environmental stresses (including heat, ultraviolet irradiation and oxidative stress) promoted the formation of aggregates. Moreover, the intracellular S78F and S78P aggregates could be reversed by lanosterol. Molecular dynamic simulation indicated that both mutations disrupted the structural integrity of Greek-key motif 2. Hence, our results reveal the vital role of conserved Ser78 in maintaining the structural stability, which can offer new insights into the mechanism of cataract formation.
Collapse
Affiliation(s)
- Ningqin Lin
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang Province, China; Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Ying Zhang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Xiaohui Song
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Chenqi Luo
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Qing Tian
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China.
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China.
| | - Lidan Hu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang Province, China.
| |
Collapse
|
10
|
Posadas Y, Sánchez-López C, Quintanar L. Copper binding and protein aggregation: a journey from the brain to the human lens. RSC Chem Biol 2023; 4:974-985. [PMID: 38033729 PMCID: PMC10685798 DOI: 10.1039/d3cb00145h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/11/2023] [Indexed: 12/02/2023] Open
Abstract
Metal ions have been implicated in several proteinopathies associated to degenerative and neurodegenerative diseases. While the molecular mechanisms for protein aggregation are still under investigation, recent findings from Cryo-EM point out to polymorphisms in aggregates obtained from patients, as compared to those formed in vitro, suggesting that several factors may impact aggregation in vivo. One of these factors could be the direct binding of metal ions to the proteins engaged in aggregate formation. In this opinion article, three case studies are discussed to address the question of how metal ion binding to a peptide or protein may impact its conformation, folding, and aggregation, and how this may be relevant in understanding the polymorphic nature of the aggregates related to disease. Specifically, the impact of Cu2+ ions in the amyloid aggregation of amyloid-β and amylin (or IAPP- islet amyloid polypeptide) are discussed and then contrasted to the case of Cu2+-induced non-amyloid aggregation of human lens γ-crystallin proteins. For the intrinsically disordered peptides amyloid-β and IAPP, the impact of Cu2+ ion binding is highly dependent on the relative location of the metal binding site and the hydrophobic regions involved in β-sheet folding and amyloid formation. Further structural studies of how Cu2+ binding impacts amyloid aggregation pathways and the molecular structure of the final amyloid fibril, both, in vitro and in vivo, will certainly shed light into the molecular origins of the polymorphisms observed in diseased tissue. Finally, contrasting these cases to that of Cu2+-induced non-amyloid aggregation of γ-crystallins, it is evident that, although the impact in aggregation - and the nature of the aggregate - may differ in each system, at the molecular level there is a competition between metal ion coordination and the stability of β-sheet structures. Considering the importance of the β-sheet fold in biology, it is fundamental to understand the energetics and molecular details behind such competition. This opinion article aims to highlight future research directions in the field that can help tackle the important question of how metal ion binding may impact protein folding and aggregation and how this relates to disease.
Collapse
Affiliation(s)
- Yanahi Posadas
- Center for Research in Aging, Center for Research and Advanced Studies (Cinvestav) Mexico City 14330 Mexico
| | - Carolina Sánchez-López
- Center for Research in Aging, Center for Research and Advanced Studies (Cinvestav) Mexico City 14330 Mexico
| | - Liliana Quintanar
- Center for Research in Aging, Center for Research and Advanced Studies (Cinvestav) Mexico City 14330 Mexico
- Department of Chemistry, Center for Research and Advanced Studies (Cinvestav) Mexico City 07350 Mexico
| |
Collapse
|
11
|
Fedorov D, Roas-Escalona N, Tolmachev D, Harmat AL, Scacchi A, Sammalkorpi M, Aranko AS, Linder MB. Triblock Proteins with Weakly Dimerizing Terminal Blocks and an Intrinsically Disordered Region for Rational Design of Condensate Properties. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2306817. [PMID: 37964343 DOI: 10.1002/smll.202306817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/20/2023] [Indexed: 11/16/2023]
Abstract
Condensates are molecular assemblies that are formed through liquid-liquid phase separation and play important roles in many biological processes. The rational design of condensate formation and their properties is central to applications, such as biosynthetic materials, synthetic biology, and for understanding cell biology. Protein engineering is used to make a triblock structure with varying terminal blocks of folded proteins on both sides of an intrinsically disordered mid-region. Dissociation constants are determined in the range of micromolar to millimolar for a set of proteins suitable for use as terminal blocks. Varying the weak dimerization of terminal blocks leads to an adjustable tendency for condensate formation while keeping the intrinsically disordered region constant. The dissociation constants of the terminal domains correlate directly with the tendency to undergo liquid-liquid phase separation. Differences in physical properties, such as diffusion rate are not directly correlated with the strength of dimerization but can be understood from the properties and interplay of the constituent blocks. The work demonstrates the importance of weak interactions in condensate formation and shows a principle for protein design that will help in fabricating functional condensates in a predictable and rational way.
Collapse
Affiliation(s)
- Dmitrii Fedorov
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - Nelmary Roas-Escalona
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - Dmitry Tolmachev
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - Adam L Harmat
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - Alberto Scacchi
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Department of Applied Physics, Aalto University, P.O. Box 11000, Aalto, FI-00076, Finland
| | - Maria Sammalkorpi
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - A Sesilja Aranko
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| | - Markus B Linder
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, Aalto, FI-00076, Finland
| |
Collapse
|
12
|
Ghosh D, Sojitra KA, Biswas A, Agarwal M, Radhakrishna M. Effect of mutations on the folding and stability of γD-crystallin protein. J Biomol Struct Dyn 2023:1-15. [PMID: 37830785 DOI: 10.1080/07391102.2023.2266768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/25/2023] [Indexed: 10/14/2023]
Abstract
Interprotein interactions between the partially unfolded states of γD-crystallin (γD-crys) protein are known to cause cataracts. Therefore, understanding the unfolding pathways of native γD-crys is extremely crucial to delineate their aggregation mechanism. In this study, we have performed extensive all-atom Molecular Dynamics simulations with explicit solvent to understand the role of the critical residues that drive the stability of the motifs and domains of γD-crys in its wild type and mutant forms. Our findings show that while the individual motifs of wild type are not stable in the native form, the individual domains remain structurally stable at 425K. This enhanced stability of the domain was attributed to the hydrophobic interactions between the motifs. Single and double point mutations of the domains with negatively charged aspartic and glutamic acid amino acid residues (I3E, W42D, W42E, I3D/W42D, I3E/W42E, and L92D/W157D) decreases the structural stability, leading to unfolding of individual domains of γD-crys. We believe that our study sheds light on the weakest links of γD-crys, along with the role of interactions stabilizing the domains. Further, this study bolsters and provides a better understanding of the domain swapping mechanism of aggregation of γD-crys.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Deepshikha Ghosh
- Department of Biological Sciences and Engineering, Indian Institute of Technology (IIT), Gandhinagar, Palaj, Gujarat, India
| | - Kandarp Ashokbhai Sojitra
- Replace with:Department of Chemical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat, India
| | - Anushka Biswas
- Replace with:Department of Chemical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat, India
| | - Manish Agarwal
- Computer Services Centre, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, Delhi
| | - Mithun Radhakrishna
- Replace with:Department of Chemical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat, India
- Center for Biomedical Engineering, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gujarat, India
| |
Collapse
|
13
|
Brudar S, Hribar-Lee B. The mechanism of self-association of human γ-D crystallin from molecular dynamics simulations. J Mol Liq 2023; 386:122461. [PMID: 38390392 PMCID: PMC10883480 DOI: 10.1016/j.molliq.2023.122461] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The aggregation of human γ-D crystallin is associated with the age-onset cataract formation. Here, we extensively investigated the self-association mechanism of human γ-D crystallin through molecular dynamics computer simulations. By mutating the protein surface we found that electrostatic interactions between charged amino acids play a crucial role in its self-association. We have confirmed the two-fold role of arginine molecules. If they are located as residues on the protein surface they can initiate protein contacts and contribute to their stickiness with noteworthy hydrophobic interactions through stacking of their methylene groups. But if they are added as free arginine in the protein solution they can also stabilize it, by associating with the protein surface and also with themselves to form effective inter-protein spacers that obstruct protein aggregation.
Collapse
Affiliation(s)
- Sandi Brudar
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, Ljubljana, SI-1000, Slovenia
| | - Barbara Hribar-Lee
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, Ljubljana, SI-1000, Slovenia
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
Yadav N, Palkhede JD, Kim SY. Anti-Glucotoxicity Effect of Phytoconstituents via Inhibiting MGO-AGEs Formation and Breaking MGO-AGEs. Int J Mol Sci 2023; 24:ijms24087672. [PMID: 37108833 PMCID: PMC10141761 DOI: 10.3390/ijms24087672] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/16/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
The therapeutic benefits of phytochemicals in the treatment of various illnesses and disorders are well documented. They show significant promise for the discovery and creation of novel medications for treating a variety of human diseases. Numerous phytoconstituents have shown antibiotic, antioxidant, and wound-healing effects in the conventional system. Traditional medicines based on alkaloids, phenolics, tannins, saponins, terpenes, steroids, flavonoids, glycosides, and phytosterols have been in use for a long time and are crucial as alternative treatments. These phytochemical elements are crucial for scavenging free radicals, capturing reactive carbonyl species, changing protein glycation sites, inactivating carbohydrate hydrolases, fighting pathological conditions, and accelerating the healing of wounds. In this review, 221 research papers have been reviewed. This research sought to provide an update on the types and methods of formation of methylglyoxal-advanced glycation end products (MGO-AGEs) and molecular pathways induced by AGEs during the progression of the chronic complications of diabetes and associated diseases as well as to discuss the role of phytoconstituents in MGO scavenging and AGEs breaking. The development and commercialization of functional foods using these natural compounds can provide potential health benefits.
Collapse
Affiliation(s)
- Neera Yadav
- College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
- School of Medicine, Kyung Hee University, Dongdaemun-gu, Seoul 02447, Republic of Korea
| | - Jyoti Dnyaneshwar Palkhede
- Department of Chemistry, College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| | - Sun-Yeou Kim
- College of Pharmacy, Gachon University, #191, Hambakmoero, Yeonsu-gu, Incheon 21936, Republic of Korea
| |
Collapse
|
16
|
Palomino-Vizcaino G, Schuth N, Domínguez-Calva JA, Rodríguez-Meza O, Martínez-Jurado E, Serebryany E, King JA, Kroll T, Costas M, Quintanar L. Copper Reductase Activity and Free Radical Chemistry by Cataract-Associated Human Lens γ-Crystallins. J Am Chem Soc 2023; 145:6781-6797. [PMID: 36918380 DOI: 10.1021/jacs.2c13397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Cataracts are caused by high-molecular-weight aggregates of human eye lens proteins that scatter light, causing lens opacity. Metal ions have emerged as important potential players in the etiology of cataract disease, as human lens γ-crystallins are susceptible to metal-induced aggregation. Here, the interaction of Cu2+ ions with γD-, γC-, and γS-crystallins, the three most abundant γ-crystallins in the lens, has been evaluated. Cu2+ ions induced non-amyloid aggregation in all three proteins. Solution turbidimetry, sodium dodecyl sulfate poly(acrylamide) gel electrophoresis (SDS-PAGE), circular dichroism, and differential scanning calorimetry showed that the mechanism for Cu-induced aggregation involves: (i) loss of β-sheet structure in the N-terminal domain; (ii) decreased thermal and kinetic stability; (iii) formation of metal-bridged species; and (iv) formation of disulfide-bridged dimers. Isothermal titration calorimetry (ITC) revealed distinct Cu2+ binding affinities in the γ-crystallins. Electron paramagnetic resonance (EPR) revealed two distinct Cu2+ binding sites in each protein. Spin quantitation demonstrated the reduction of γ-crystallin-bound Cu2+ ions to Cu+ under aerobic conditions, while X-ray absorption spectroscopy (XAS) confirmed the presence of linear or trigonal Cu+ binding sites in γ-crystallins. Our EPR and XAS studies revealed that γ-crystallins' Cu2+ reductase activity yields a protein-based free radical that is likely a Tyr-based species in human γD-crystallin. This unique free radical chemistry carried out by distinct redox-active Cu sites in human lens γ-crystallins likely contributes to the mechanism of copper-induced aggregation. In the context of an aging human lens, γ-crystallins could act not only as structural proteins but also as key players for metal and redox homeostasis.
Collapse
Affiliation(s)
- Giovanni Palomino-Vizcaino
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Nils Schuth
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - José A Domínguez-Calva
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Oscar Rodríguez-Meza
- Laboratorio de Biofisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico
| | - Eduardo Martínez-Jurado
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| | - Eugene Serebryany
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Miguel Costas
- Laboratorio de Biofisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City 07360, Mexico
| |
Collapse
|
17
|
Diessner EM, Freites JA, Tobias DJ, Butts CT. Network Hamiltonian Models for Unstructured Protein Aggregates, with Application to γD-Crystallin. J Phys Chem B 2023; 127:685-697. [PMID: 36637342 PMCID: PMC10437096 DOI: 10.1021/acs.jpcb.2c07672] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Network Hamiltonian models (NHMs) are a framework for topological coarse-graining of protein-protein interactions, in which each node corresponds to a protein, and edges are drawn between nodes representing proteins that are noncovalently bound. Here, this framework is applied to aggregates of γD-crystallin, a structural protein of the eye lens implicated in cataract disease. The NHMs in this study are generated from atomistic simulations of equilibrium distributions of wild-type and the cataract-causing variant W42R in solution, performed by Wong, E. K.; Prytkova, V.; Freites, J. A.; Butts, C. T.; Tobias, D. J. Molecular Mechanism of Aggregation of the Cataract-Related γD-Crystallin W42R Variant from Multiscale Atomistic Simulations. Biochemistry2019, 58 (35), 3691-3699. Network models are shown to successfully reproduce the aggregate size and structure observed in the atomistic simulation, and provide information about the transient protein-protein interactions therein. The system size is scaled from the original 375 monomers to a system of 10000 monomers, revealing a lowering of the upper tail of the aggregate size distribution of the W42R variant. Extrapolation to higher and lower concentrations is also performed. These results provide an example of the utility of NHMs for coarse-grained simulation of protein systems, as well as their ability to scale to large system sizes and high concentrations, reducing computational costs while retaining topological information about the system.
Collapse
Affiliation(s)
- Elizabeth M Diessner
- Department of Chemistry, University of California, Irvine, California92697, United States
| | - J Alfredo Freites
- Department of Chemistry, University of California, Irvine, California92697, United States
| | - Douglas J Tobias
- Department of Chemistry, University of California, Irvine, California92697, United States
| | - Carter T Butts
- Departments of Sociology, Statistics, Computer Science, and EECS, University of California, Irvine, California92697, United States
| |
Collapse
|
18
|
Strofaldi A, Quinn MK, Seddon AM, McManus JJ. Polymorphic protein phase transitions driven by surface anisotropy. J Chem Phys 2023; 158:014905. [PMID: 36610968 DOI: 10.1063/5.0125452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Phase transitions of proteins are strongly influenced by surface chemical modifications or mutations. Human γD-crystallin (HGD) single-mutants have been extensively studied because they are associated with the onset of juvenile cataract. However, they have also provided a rich library of molecules to examine how specific inter-protein interactions direct protein assembly, providing new insights and valuable experimental data for coarse-grained patchy-particle models. Here, we demonstrate that the addition of new inter-protein interactions by mutagenesis is additive and increases the number and variety of condensed phases formed by proteins. When double mutations incorporating two specific single point mutations are made, the properties of both single mutations are retained in addition to the formation of a new condensed phase. We find that the HGD double-mutant P23VC110M self-assembles into spherical particles with retrograde solubility, orthorhombic crystals, and needle/plate shape crystals, while retaining the ability to undergo liquid-liquid phase separation. This rich polymorphism is only partially predicted by the experimental data on the constituent single mutants. We also report a previously un-characterized amorphous protein particle, with unique properties that differ from those of protein spherulites, protein particulates previously described. The particles we observe are amorphous, reversible with temperature, tens of microns in size, and perfectly spherical. When they are grown on pristine surfaces, they appear to form by homogeneous nucleation, making them unique, and we believe a new form of protein condensate. This work highlights the challenges in predicting protein behavior, which has frustrated rational assembly and crystallization but also provides rich data to develop new coarse-grained models to explain the observed polymorphism.
Collapse
Affiliation(s)
| | - Michelle K Quinn
- Department of Chemistry Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Annela M Seddon
- HH Wills Physics Laboratory, School of Physics, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Jennifer J McManus
- HH Wills Physics Laboratory, School of Physics, University of Bristol, Bristol BS8 1TL, United Kingdom
| |
Collapse
|
19
|
Islam S, Do M, Frank BS, Hom GL, Wheeler S, Fujioka H, Wang B, Minocha G, Sell DR, Fan X, Lampi KJ, Monnier VM. α-Crystallin chaperone mimetic drugs inhibit lens γ-crystallin aggregation: potential role for cataract prevention. J Biol Chem 2022; 298:102417. [PMID: 36037967 PMCID: PMC9525908 DOI: 10.1016/j.jbc.2022.102417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/29/2022] Open
Abstract
Γ-Crystallins play a major role in age-related lens transparency. Their destabilization by mutations and physical chemical insults are associated with cataract formation. Therefore, drugs that increase their stability should have anticataract properties. To this end, we screened 2560 Federal Drug Agency–approved drugs and natural compounds for their ability to suppress or worsen H2O2 and/or heat-mediated aggregation of bovine γ-crystallins. The top two drugs, closantel (C), an antihelminthic drug, and gambogic acid (G), a xanthonoid, attenuated thermal-induced protein unfolding and aggregation as shown by turbidimetry fluorescence spectroscopy dynamic light scattering and electron microscopy of human or mouse recombinant crystallins. Furthermore, binding studies using fluorescence inhibition and hydrophobic pocket–binding molecule bis-8-anilino-1-naphthalene sulfonic acid revealed static binding of C and G to hydrophobic sites with medium-to-low affinity. Molecular docking to HγD and other γ-crystallins revealed two binding sites, one in the “NC pocket” (residues 50–150) of HγD and one spanning the “NC tail” (residues 56–61 to 168–174 in the C-terminal domain). Multiple binding sites overlap with those of the protective mini αA-crystallin chaperone MAC peptide. Mechanistic studies using bis-8-anilino-1-naphthalene sulfonic acid as a proxy drug showed that it bound to MAC sites, improved Tm of both H2O2 oxidized and native human gamma D, and suppressed turbidity of oxidized HγD, most likely by trapping exposed hydrophobic sites. The extent to which these drugs act as α-crystallin mimetics and reduce cataract progression remains to be demonstrated. This study provides initial insights into binding properties of C and G to γ-crystallins.
Collapse
Affiliation(s)
- Sidra Islam
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Michael Do
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Brett S Frank
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Grant L Hom
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Samuel Wheeler
- Dept of Integrative Biosciences, Oregon Health & Sciences University, Portland, OR 97239
| | - Hisashi Fujioka
- Cryo-EM Core Facility, School of Medicine, Case Western Reserve University, Case Western Reserve University, Cleveland, OH 44016
| | - Benlian Wang
- Center for Proteomics and Bioinformatics, Dept of Nutrition, Case Western Reserve University, Cleveland, OH 44106
| | - Geeta Minocha
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - David R Sell
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106
| | - Xingjun Fan
- Dept of Cell Biology and Anatomy, Augusta University, Georgia, GA 30912
| | - Kirsten J Lampi
- Dept of Integrative Biosciences, Oregon Health & Sciences University, Portland, OR 97239
| | - Vincent M Monnier
- Dept of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106; Dept of Biochemistry, Case Western Reserve University, Cleveland OH 44106.
| |
Collapse
|
20
|
Serebryany E, Chowdhury S, Woods CN, Thorn DC, Watson NE, McClelland AA, Klevit RE, Shakhnovich EI. A native chemical chaperone in the human eye lens. eLife 2022; 11:76923. [PMID: 35723573 PMCID: PMC9246369 DOI: 10.7554/elife.76923] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/13/2022] [Indexed: 12/02/2022] Open
Abstract
Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol’s molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol’s primary target was not the native, unfolded, or final aggregated states of the protein; rather, we propose that it was the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.
Collapse
Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Sourav Chowdhury
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Christopher N Woods
- Department of Biochemistry, University of Washington, Seattle, United States
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Nicki E Watson
- Center for Nanoscale Systems, Harvard University, Cambridge, United States
| | | | - Rachel E Klevit
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| |
Collapse
|
21
|
Li H, Yu Y, Ruan M, Jiao F, Chen H, Gao J, Weng Y, Bao Y. The mechanism for thermal-enhanced chaperone-like activity of α-crystallin against UV irradiation-induced aggregation of γD-crystallin. Biophys J 2022; 121:2233-2250. [PMID: 35619565 DOI: 10.1016/j.bpj.2022.05.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/11/2022] [Accepted: 05/20/2022] [Indexed: 11/18/2022] Open
Abstract
Exposure to solar UV irradiation damages γ-crystallin, leading to cataract formation via aggregation. α-Crystallin, as a small heat-shock protein (sHsps), efficiently suppresses this irreversible aggregation by selectively binding the denatured γ-crystallin monomer. In this study, liquid chromatography tandem mass spectrometry (LC-MS) was used to evaluate UV-325 nm irradiation-induced photodamage of human γD-crystallin in the presence of bovine α-crystallin, atomic force microscope (AFM) and dynamic light scattering (DLS) techniques were used to detect the quaternary structure changes of α-crystallin oligomer, and Fourier transform infrared (FTIR) spectroscopy and temperature-jump (T-jump) nanosecond time-resolved IR absorbance difference spectroscopy were used to probe the secondary structure changes of bovine α-crystallin. We find that the thermal-induced subunit dissociation of α-crystallin oligomer involves the breaking of hydrogen bonds at the dimeric interface, leading to three different spectral components at varied temperature regions as resolved from temperature-dependent IR spectra. Under UV-325 nm irradiation, unfolded γD-crystallin binds to the dissociated α-crystallin subunit to form αγ-complex, then follows the reassociation of αγ-complex to the partially dissociated α-crystallin oligomer. This prevents the aggregation of denatured γD-crystallin. The formation of the γD-bound α-crystallin oligomer is further confirmed by AFM and DLS analysis, which reveals an obvious size expansion in the reassociated αγ-oligomers. In addition, UV-325 nm irradiation causes a peptide bond cleavage of γD-crystallin at Ala158 in presence of α-crystallin. Our results suggest a very effective protection mechanism for subunits dissociated from α-crystallin oligomers against UV irradiation-induced aggregation of γD-crystallin, at an expense of a loss of a short C-terminal peptide in γD-crystallin.
Collapse
Affiliation(s)
- Hao Li
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; College of Chemical Biology and Biotechnology, Beijing University Shenzhen Graduate School, Shenzhen, China; Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yingying Yu
- Department of Ophthalmology, Peking University People's Hospital, Eye Diseases and Optometry Institute, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, College of Optometry, Peking University Health Science Center, Beijing, China
| | - Meixia Ruan
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Fang Jiao
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Hailong Chen
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jiali Gao
- College of Chemical Biology and Biotechnology, Beijing University Shenzhen Graduate School, Shenzhen, China; Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Yuxiang Weng
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Yongzhen Bao
- Department of Ophthalmology, Peking University People's Hospital, Eye Diseases and Optometry Institute, Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, College of Optometry, Peking University Health Science Center, Beijing, China.
| |
Collapse
|
22
|
Hsueh SS, Wang SS(S, Chen SH, Wang CL, Wu W(J, Lin TH. Insights to Human γD-Crystallin Unfolding by NMR Spectroscopy and Molecular Dynamics Simulations. Int J Mol Sci 2022; 23:ijms23031591. [PMID: 35163513 PMCID: PMC8836049 DOI: 10.3390/ijms23031591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/13/2022] [Accepted: 01/19/2022] [Indexed: 11/16/2022] Open
Abstract
Human γD-crystallin (HGDC) is an abundant lens protein residing in the nucleus of the human lens. Aggregation of this and other structural proteins within the lens leads to the development of cataract. Much has been explored on the stability and aggregation of HGDC and where detailed investigation at the atomic resolution was needed, the X-ray structure was used as an initial starting conformer for molecular modeling. In this study, we implemented NMR-solution HGDC structures as starting conformers for molecular dynamics simulations to provide the missing pieces of the puzzle on the very early stages of HGDC unfolding leading up to the domain swap theories proposed by past studies. The high-resolution details of the conformational dynamics also revealed additional insights to possible early intervention for cataractogenesis.
Collapse
Affiliation(s)
- Shu-Shun Hsueh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan; (S.-S.H.); (S.-S.W.); (S.-H.C.)
| | - S.-S. (Steven) Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan; (S.-S.H.); (S.-S.W.); (S.-H.C.)
| | - Shu-Han Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan; (S.-S.H.); (S.-S.W.); (S.-H.C.)
| | - Chia-Lin Wang
- Laboratory of Nuclear Magnetic Resonance, Medical Research Department, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
| | - W. (Josephine) Wu
- Department of Optometry, Yuanpei University of Medical Technology, Hsinchu City 30015, Taiwan
- Correspondence: (J.W.W.); (T.-H.L.); Tel.: +886-3-538-1183 (ext. 8608) (W.W.); +886-2-28712121 (ext. 2703) (T.-H.L.)
| | - Ta-Hsien Lin
- Laboratory of Nuclear Magnetic Resonance, Medical Research Department, Taipei Veterans General Hospital, Taipei 11217, Taiwan;
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
- Correspondence: (J.W.W.); (T.-H.L.); Tel.: +886-3-538-1183 (ext. 8608) (W.W.); +886-2-28712121 (ext. 2703) (T.-H.L.)
| |
Collapse
|
23
|
Aguayo-Ortiz R, Guzmán-Ocampo DC, Dominguez L. Insights into the binding of morin to human γD-crystallin. Biophys Chem 2021; 282:106750. [PMID: 34999344 DOI: 10.1016/j.bpc.2021.106750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/19/2021] [Accepted: 12/21/2021] [Indexed: 11/28/2022]
Abstract
Crystallin aggregation in the eye lens is one of the leading causes of cataract formation. The increase in the human γD-crystallin (HγDC) aggregation propensity has been associated with the oligomerization of its partially folded and fully unfolded structure. A recent study demonstrated that the binding of flavonoid morin (MOR) to HγDC inhibits the fibrillation of this protein. In this work, we carry out an exhaustive search for the possible binding site of MOR on HγDC by combining an ensemble docking approach with the Wrap 'N' Shake protocol. In agreement with previous results, we found a potential MOR-binding site in the cleft formed between the N-terminal and C-terminal domains of HγDC. MOR preference for the cleft residues was observed even with the interface-opened intermediate conformers of HγDC. In addition, metadynamics simulations were carried out to corroborate the stabilizing activity of MOR on HγDC structure and to identify the structural regions implicated during the unfolding inhibition. Overall, this study provides relevant insights into the identification of new HγDC aggregation inhibitors.
Collapse
Affiliation(s)
- Rodrigo Aguayo-Ortiz
- Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Dulce C Guzmán-Ocampo
- Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Laura Dominguez
- Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico.
| |
Collapse
|
24
|
Strofaldi A, Khan AR, McManus JJ. Surface Exposed Free Cysteine Suppresses Crystallization of Human γD-Crystallin. J Mol Biol 2021; 433:167252. [PMID: 34537240 DOI: 10.1016/j.jmb.2021.167252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 11/28/2022]
Abstract
Human γD-crystallin (HGD) has remarkable stability against condensation in the human lens, sometimes over a whole lifetime. The native protein has a surface exposed free cysteine that forms dimers (Benedek, 1997; Ramkumar et al., 1864)1,2 without specific biological function and leads to further protein association and/or aggregation, which creates a paradox for understanding its stability. Previous work has demonstrated that chemical modification of the protein at the free cysteine (C110), increases the temperature at which liquid-liquid phase separation occurs (LLPS), lowers protein solubility and suggests an important role for this amino acid in maintaining its long-term resistance to condensation. Here we demonstrate that mutation of the cysteine does not alter the structure or solubility (liquidus) line for the protein, but dramatically increases the protein crystal nucleation rate following LLPS, suggesting that the free cysteine has a vital role in suppressing crystallization in the human lens.
Collapse
Affiliation(s)
- Alessandro Strofaldi
- Department of Chemistry, Maynooth University, Maynooth, Co. Kildare, Ireland; H. H Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Amir R Khan
- Division of Newborn Medicine, Boston Children's Hospital, Boston, USA; School of Biochemistry, Trinity College Dublin, Ireland
| | - Jennifer J McManus
- H. H Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom.
| |
Collapse
|
25
|
Meric G, Naik S, Hunter AK, Robinson AS, Roberts CJ. Challenges for design of aggregation-resistant variants of granulocyte colony-stimulating factor. Biophys Chem 2021; 277:106630. [PMID: 34119805 DOI: 10.1016/j.bpc.2021.106630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/14/2021] [Accepted: 05/31/2021] [Indexed: 01/15/2023]
Abstract
Non-native protein aggregation is a long-standing issue in pharmaceutical biotechnology. A rational design approach was used in order to identify variants of recombinant human granulocyte colony-stimulating factor (rhG-CSF) with lower aggregation propensity at solution conditions that are typical of commercial formulation. The approach used aggregation-prone-region (APR) predictors to select single amino acid substitutions that were predicted to decrease intrinsic aggregation propensity (IAP). The results of static light scattering temperature-ramps and chemical unfolding experiments demonstrated that none of the selected variants exhibited improved aggregation resistance, and the apparent conformational stability of each variant was lower than that of WT. Aggregation studies under partly denaturing conditions suggested that the IAP of at least one variant remained unaltered. Overall, this study highlights a general challenge in designing aggregation resistance for proteins, due to the need to accurately predict both APRs and conformational stability.
Collapse
Affiliation(s)
- Gulsum Meric
- Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States.
| | - Subhashchandra Naik
- Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States.
| | - Alan K Hunter
- Biopharmaceuticals Development, R&D, AstraZeneca, Gaithersburg, MD 20878, United States.
| | - Anne S Robinson
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
| | - Christopher J Roberts
- Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716, United States.
| |
Collapse
|
26
|
Serebryany E, Thorn DC, Quintanar L. Redox chemistry of lens crystallins: A system of cysteines. Exp Eye Res 2021; 211:108707. [PMID: 34332989 PMCID: PMC8511183 DOI: 10.1016/j.exer.2021.108707] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/09/2021] [Accepted: 07/23/2021] [Indexed: 11/28/2022]
Abstract
The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the β- and α-crystallins where pertinent.
Collapse
Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, Mexico
| |
Collapse
|
27
|
Zhou H, Li Y, Yang Y, Liu S, Yang Z. Lanosterol reduces the aggregation propensity of ultraviolet-damaged human γD-crystallins: a molecular dynamics study. Phys Chem Chem Phys 2021; 23:13696-13704. [PMID: 34128026 DOI: 10.1039/d1cp00132a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Ultraviolet (UV) radiation-induced oxidation of tryptophan (Trp) to kynurenine (KN) (TRP > KN) in human γD-crystallins (HγD-Crys) promotes the conversion of proteins into partially unfolded species that act as important precursors for sequential large-scale aggregation. Herein, we report that lanosterol shows protective activity to the structure of the TRP > KN mutant HγD-Crys, particularly its N-terminal domain (N-td), by using all-atom molecular dynamics simulations. The Trp68 > KN mutation significantly destabilizes the originally highly stable "Tyr55-Trp68-Tyr62" cluster, thereby causing loop2, where the mutation occurs, to become very flexible. The large fluctuation of loop2 induces cracks, which appear on the protein surface, resulting in the intrusion of water molecules into the hydrophobic core of the N-td. This event eventually triggers the unfolding of the N-td. However, lanosterol can suppress the large fluctuation of loop2 to protect the structural stability of the mutant N-td, thus reducing the aggregation propensity of the TRP > KN mutant HγD-Crys. This structure protective activity of lanosterol arises from its capability to preferentially bind to the hydrophobic regions near loop2. Thus, lanosterol acts as a "water blocker" to prevent the invasion of solvent molecules into the hydrophobic core. These findings provide some valuable insights into the development of potential lanosterol-based drugs for cataract prevention and treatment.
Collapse
Affiliation(s)
- Hong Zhou
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
| | - Youyun Li
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
| | - Ying Yang
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
| | - Shengtang Liu
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
| | - Zaixing Yang
- State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
| |
Collapse
|
28
|
Rocha MA, Sprague-Piercy MA, Kwok AO, Roskamp KW, Martin RW. Chemical Properties Determine Solubility and Stability in βγ-Crystallins of the Eye Lens. Chembiochem 2021; 22:1329-1346. [PMID: 33569867 PMCID: PMC8052307 DOI: 10.1002/cbic.202000739] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Indexed: 11/10/2022]
Abstract
βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.
Collapse
Affiliation(s)
- Megan A. Rocha
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Marc A. Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| | - Ashley O. Kwok
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| |
Collapse
|
29
|
Mondal B, Nagesh J, Reddy G. Double Domain Swapping in Human γC and γD Crystallin Drives Early Stages of Aggregation. J Phys Chem B 2021; 125:1705-1715. [PMID: 33566611 DOI: 10.1021/acs.jpcb.0c07833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human γD (HγD) and γC (HγC) are two-domain crystallin (Crys) proteins expressed in the nucleus of the eye lens. Structural perturbations in the protein often trigger aggregation, which eventually leads to cataract. To decipher the underlying molecular mechanism, it is important to characterize the partially unfolded conformations, which are aggregation-prone. Using a coarse grained protein model and molecular dynamics simulations, we studied the role of on-pathway folding intermediates in the early stages of aggregation. The multidimensional free energy surface revealed at least three different folding pathways with the population of partially structured intermediates. The two dominant pathways confirm sequential folding of the N-terminal [Ntd] and the C-terminal domains [Ctd], while the third, least favored, pathway involves intermediates where both the domains are partially folded. A native-like intermediate (I*), featuring the folded domains and disrupted interdomain contacts, gets populated in all three pathways. I* forms domain swapped dimers by swapping the entire Ntds and Ctds with other monomers. Population of such oligomers can explain the increased resistance to unfolding resulting in hysteresis observed in the folding experiments of HγD Crys. An ensemble of double domain swapped dimers are also formed during refolding, where intermediates consisting of partially folded Ntds and Ctds swap secondary structures with other monomers. The double domain swapping model presented in our study provides structural insights into the early events of aggregation in Crys proteins and identifies the key secondary structural swapping elements, where introducing mutations will aid in regulating the overall aggregation propensity.
Collapse
Affiliation(s)
- Balaka Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, Karnataka, India 560012
| | - Jayashree Nagesh
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, Karnataka, India 560012
| | - Govardhan Reddy
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, Karnataka, India 560012
| |
Collapse
|
30
|
Velasco-Bolom JL, Domínguez L. Exploring the folding process of human βB2-crystallin using multiscale molecular dynamics and the Markov state model. Phys Chem Chem Phys 2021; 22:26753-26763. [PMID: 33205789 DOI: 10.1039/d0cp04136j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Adequate knowledge of protein conformations is crucial for understanding their function and their association properties with other proteins. The cataract disease is correlated with conformational changes in key proteins called crystallins. These changes are due to mutations or post-translational modifications that may lead to protein unfolding, and thus the formation of aggregate states. Human βB2-crystallin (HβB2C) is found in high proportion in the eye lens, and its mutations are related to some cataracts. HβB2C also associates into dimers, tetramers, and other higher-order supramolecular complexes. However, it is the only protein of the βγ-crystallin family that has been found in an extended conformation. Therefore, we hypothesize that the extended conformation is not energetically favourable and that HβB2C may adopt a closed (completely folded) conformation, similar to the other members of the βγ-crystallin family. To corroborate this hypothesis, we performed extensive molecular dynamics simulations of HβB2C in its monomeric and dimeric conformations, using all-atom and coarse-grained scales. We employed Markov state model (MSM) analysis to characterize the conformational and kinetically relevant states in the folding process of monomeric HβB2C. The MSM analysis clearly shows that HβB2C adopts a completely folded structure, and this conformation is the most kinetically and energetically favourable one. In contrast, the extended conformations are kinetically unstable and energetically unfavourable. Our MSM analysis also reveals a key metastable state, which is particularly interesting because it is from this state that the folded state is reached. The folded state is stabilized by the formation of two salt bridges between the residue-pairs E74-R187 and R97-E166 and the two hydrophobic residue-pairs V59-L164 and V72-V151. Furthermore, free energy surface (FES) analysis revealed that the HβB2C dimer with both monomers in a closed conformation (face-en-face dimer) is energetically more stable than the domain-swapped dimer (crystallographic structure). The results presented in this report shed light on the molecular details of the folding mechanism of HβB2C in an aqueous environment and may contribute to interpreting different experimental findings. Finally, a detailed knowledge of HβB2C folding may be key to the rational design of potential molecules to treat cataract disease.
Collapse
Affiliation(s)
- José-Luis Velasco-Bolom
- Facultad de Química, Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico.
| | | |
Collapse
|
31
|
Brudar S, Gujt J, Spohr E, Hribar-Lee B. Studying the mechanism of phase separation in aqueous solutions of globular proteins via molecular dynamics computer simulations. Phys Chem Chem Phys 2021; 23:415-424. [PMID: 33319872 PMCID: PMC8210815 DOI: 10.1039/d0cp05160h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proteins are the most abundant biomacromolecules in living cells, where they perform vital roles in virtually every biological process. To maintain their function, proteins need to remain in a stable (native) state. Inter- and intramolecular interactions in aqueous protein solutions govern the fate of proteins, as they can provoke their unfolding or association into aggregates. The initial steps of protein aggregation are difficult to capture experimentally, therefore we used molecular dynamics simulations in this study. We investigated the initial phase of aggregation of two different lysozymes, hen egg-white (HEWL) and T4 WT* lysozyme and also human lens γ-D crystallin by using atomistic simulations. We monitored the phase stability of their aqueous solutions by calculating time-dependent density fluctuations. We found that all proteins remained in their compact form despite aggregation. With an extensive analysis of intermolecular residue-residue interactions we discovered that arginine is of paramount importance in the initial stage of aggregation of HEWL and γ-D crystallin, meanwhile lysine was found to be the most involved amino acid in forming initial contacts between T4 WT* molecules.
Collapse
Affiliation(s)
- Sandi Brudar
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, SI-1000 Ljubljana, Slovenia.
| | | | | | | |
Collapse
|
32
|
Guseman AJ, Whitley MJ, González JJ, Rathi N, Ambarian M, Gronenborn AM. Assessing the Structures and Interactions of γD-Crystallin Deamidation Variants. Structure 2020; 29:284-291.e3. [PMID: 33264606 DOI: 10.1016/j.str.2020.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 10/12/2020] [Accepted: 11/06/2020] [Indexed: 11/25/2022]
Abstract
Cataracts involve the deposition of the crystallin proteins in the vertebrate eye lens, causing opacification and blindness. They are associated with either genetic mutation or protein damage that accumulates over the lifetime of the organism. Deamidation of Asn residues in several different crystallins has been observed and is frequently invoked as a cause of cataract. Here, we investigated the properties of Asp variants, deamidation products of γD-crystallin, by solution NMR, X-ray crystallography, and other biophysical techniques. No substantive structural or stability changes were noted for all seven Asn to Asp γD-crystallins. Importantly, no changes in diffusion interaction behavior could be detected. Our combined experimental results demonstrate that introduction of single Asp residues on the surface of γD-crystallin by deamidation is unlikely to be the driver of cataract formation in the eye lens.
Collapse
Affiliation(s)
- Alex J Guseman
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
| | - Matthew J Whitley
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
| | - Jeremy J González
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
| | - Nityam Rathi
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
| | - Mikayla Ambarian
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
| | - Angela M Gronenborn
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA.
| |
Collapse
|
33
|
Cataract-Associated New Mutants S175G/H181Q of βΒ2-Crystallin and P24S/S31G of γD-Crystallin Are Involved in Protein Aggregation by Structural Changes. Int J Mol Sci 2020; 21:ijms21186504. [PMID: 32899552 PMCID: PMC7555777 DOI: 10.3390/ijms21186504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/21/2020] [Accepted: 09/01/2020] [Indexed: 12/15/2022] Open
Abstract
β/γ-Crystallins, the main structural protein in human lenses, have highly stable structure for keeping the lens transparent. Their mutations have been linked to cataracts. In this study, we identified 10 new mutations of β/γ-crystallins in lens proteomic dataset of cataract patients using bioinformatics tools. Of these, two double mutants, S175G/H181Q of βΒ2-crystallin and P24S/S31G of γD-crystallin, were found mutations occurred in the largest loop linking the distant β-sheets in the Greek key motif. We selected these double mutants for identifying the properties of these mutations, employing biochemical assay, the identification of protein modifications with nanoUPLC-ESI-TOF tandem MS and examining their structural dynamics with hydrogen/deuterium exchange-mass spectrometry (HDX-MS). We found that both double mutations decrease protein stability and induce the aggregation of β/γ-crystallin, possibly causing cataracts. This finding suggests that both the double mutants can serve as biomarkers of cataracts.
Collapse
|
34
|
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.
Collapse
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
| |
Collapse
|
35
|
Lin M, Jin Y, Chen X, Sui Y, Li Y, Li H, Ni X, Zhao N, Lu Y, Jiang M. Increased hydrophobicity of CRYGD p.(Ala159ProfsTer9): Suspected cause of congenital cataracts in a large Chinese family. Mol Genet Genomic Med 2020; 8:e1436. [PMID: 33460241 PMCID: PMC7549552 DOI: 10.1002/mgg3.1436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 12/05/2022] Open
Abstract
Objective This study aimed to identify the disease‐causing mutation of congenital cataract disease in a large northeastern Chinese family. Materials and Methods The subjects’ peripheral blood was collected, their genomic DNA was extracted, mutation screening of candidate genes was performed using polymerase chain reaction, and the amplified products were sequenced. Recombinant C‐terminal enhanced green fluorescent protein‐tagged wild‐type or mutant CRYGD was expressed in HEK293T cells, and the expression pattern was observed under a fluorescence microscope. The CRYGD protein mutation was analyzed via bioinformatics analysis. Results c.475delG, a novel frameshift mutation in CRYGD, was identified in the affected family members. This mutation causes premature termination of the polypeptide, resulting in truncated p.(Ala159ProfsTer9). According to the bioinformatics analysis results, compared with wild‐type CRYGD, p.(Ala159ProfsTer9) exhibits significantly decreased hydrophilicity. Fluorescence microscopy revealed that p.(Ala159ProfsTer9) aggregates in the cell in the form of granular deposits. Conclusion In this study, the novel frameshift mutation c.475delG, p.(Ala159ProfsTer9) in CRYGD was identified to cause congenital cataracts in a large Chinese family; increased hydrophobicity of p.(Ala159ProfsTer9) protein may be the underlying mechanism.
Collapse
Affiliation(s)
- Meina Lin
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Ying Jin
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Xinren Chen
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yu Sui
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yan Li
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Huan Li
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Xiang Ni
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Ning Zhao
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yongping Lu
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Miao Jiang
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| |
Collapse
|
36
|
Fernández-Silva A, French-Pacheco L, Rivillas-Acevedo L, Amero C. Aggregation pathways of human γ D crystallin induced by metal ions revealed by time dependent methods. PeerJ 2020; 8:e9178. [PMID: 32566392 PMCID: PMC7295030 DOI: 10.7717/peerj.9178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/22/2020] [Indexed: 12/17/2022] Open
Abstract
Cataract formation is a slow accumulative process due to protein aggregates promoted by different factors over time. Zinc and copper ions have been reported to induce the formation of aggregates opaque to light in the human gamma D crystallin (HγD) in a concentration and temperature dependent manner. In order to gain insight into the mechanism of metal-induced aggregation of HγD under conditions that mimic more closely the slow, accumulative process of the disease, we have studied the non-equilibrium process with the minimal metal dose that triggers HγD aggregation. Using a wide variety of biophysics techniques such as turbidimetry, dynamic light scattering, fluorescence, nuclear magnetic resonance and computational methods, we obtained information on the molecular mechanisms for the formation of aggregates. Zn(II) ions bind to different regions at the protein, probably with similar affinities. This binding induces a small conformational rearrangement within and between domains and aggregates via the formation of metal bridges without any detectable unfolded intermediates. In contrast, Cu(II)-induced aggregation includes a lag time, in which the N-terminal domain partially unfolds while the C-terminal domain and parts of the N-terminal domain remain in a native-like conformation. This partially unfolded intermediate is prone to form the high-molecular weight aggregates. Our results clearly show that different external factors can promote protein aggregation following different pathways.
Collapse
Affiliation(s)
- Arline Fernández-Silva
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Leidys French-Pacheco
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico.,Centro de Investigación en Dinámica Celular, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Lina Rivillas-Acevedo
- Centro de Investigación en Dinámica Celular, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| | - Carlos Amero
- Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico
| |
Collapse
|
37
|
Sharma V, Sharma S, Rana S, Ghosh KS. Inhibition of amyloid fibrillation of human γD-crystallin by gold nanoparticles: Studies at molecular level. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 233:118199. [PMID: 32151988 DOI: 10.1016/j.saa.2020.118199] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
The capability of citrate-stabilized gold nanoparticles (AuNps) has been explored for the inhibition of amyloid fibrillation of human γD-crystallin (HGD), a major protein of eye lens. Citrate-capped AuNps were synthesized, characterized and used further for amyloid inhibition. The results from intrinsic and extrinsic (in the presence of Thioflavin T and ANS) fluorescence based assays and CD spectroscopy clearly suggest that AuNps at nanomolar concentrations can act as an effective inhibitor against fibrillation of HGD. Fluorescence microscopic and transmission electron microscopic images also supported this observation. Considering the inhibitory role of AuNps against HGD fibrillation, interactions between HGD and AuNps were studied to decipher the mechanism of amyloid inhibition. The binding and quenching constants were calculated as ~109 M-1 using the data of tryptophan fluorescence quenching of HGD by AuNps. Ground state complexation between the protein and nanoparticles was predicted. AuNps were not found to cause any major conformational changes in the native protein. Entropy-driven complexation process between the protein and nanoparticles indicates the interactions of AuNps with hydrophobic residues of HGD. Therefore, in the presence of AuNps, the exposure of the hydrophobic patches of HGD during its partial unfolding became restricted, which results inhibition in HGD fibrillation.
Collapse
Affiliation(s)
- Vandna Sharma
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Shivani Sharma
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Himachal Pradesh 177005, India.
| |
Collapse
|
38
|
Rana S, Ghosh KS. Inhibition of fibrillation of human γd-crystallin by a flavonoid morin. J Biomol Struct Dyn 2020; 39:4279-4289. [PMID: 32469293 DOI: 10.1080/07391102.2020.1775701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
To inhibit the formation of amyloid fibrils by human γd-crystallin (HGD), a series of four flavonoids (quercertin, rutin, morin and hesperetin) was tested. Only morin had demonstrated significant inhibition of HGD fibrillation. Results from fluorimetric assay techniques (using thioflavin T and ANS), FTIR, circular dichroism and microscopic imaging (fluorescence microscopy and transmission electron microscopy) confirmed HGD fibrillation inhibition by morin. HGD-morin complex formation at ground state resulted tryptophan fluorescence quenching through static mechanism, which was also confirmed by determining the excited-state life time of HGD tryptophan residues. Förster resonance energy transfer occurs from HGD to morin. Synchronous, three-dimensional fluorescence, FTIR and circular dichroism results suggest that major changes in HGD conformation did not occur on binding with morin. The interactions between HGD and morin involve hydrogen bonding and/or van der Waals forces. Docking predictions also support experimental results.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Shiwani Rana
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, Himachal Pradesh, India
| | - Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, Himachal Pradesh, India
| |
Collapse
|
39
|
Breindel L, Yu J, Burz DS, Shekhtman A. Intact ribosomes drive the formation of protein quinary structure. PLoS One 2020; 15:e0232015. [PMID: 32330166 PMCID: PMC7182177 DOI: 10.1371/journal.pone.0232015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/05/2020] [Indexed: 01/19/2023] Open
Abstract
Transient, site-specific, or so-called quinary, interactions are omnipresent in live cells and modulate protein stability and activity. Quinary intreactions are readily detected by in-cell NMR spectroscopy as severe broadening of the NMR signals. Intact ribosome particles were shown to be necessary for the interactions that give rise to the NMR protein signal broadening observed in cell lysates and sufficient to mimic quinary interactions present in the crowded cytosol. Recovery of target protein NMR spectra that were broadened in lysates, in vitro and in the presence of purified ribosomes was achieved by RNase A digestion only after the structure of the ribosome was destabilized by removing magnesium ions from the system. Identifying intact ribosomal particles as the major protein-binding component of quinary interactions and consequent spectral peak broadening will facilitate quantitative characterization of macromolecular crowding effects in live cells and streamline models of metabolic activity.
Collapse
Affiliation(s)
- Leonard Breindel
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, United States of America
| | - Jianchao Yu
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, United States of America
| | - David S. Burz
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, United States of America
| | - Alexander Shekhtman
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, United States of America
| |
Collapse
|
40
|
Aguayo-Ortiz R, Dominguez L. Effects of Mutating Trp42 Residue on γD-Crystallin Stability. J Chem Inf Model 2020; 60:777-785. [PMID: 31747273 DOI: 10.1021/acs.jcim.9b00747] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Oligomerization and aggregation of γD-crystallins (HγDC) in the eye lens is one of the main causes of cataract development. To date, several congenital mutations related to this protein are known to promote the formation of aggregates. Previous studies have demonstrated that mutations in W42 residue of HγDC lead to the generation of partially unfolded intermediates that are more prone to aggregate. To understand the role of W42 in the stability of HγDC, we performed alchemical free-energy calculations and all-atom molecular dynamics simulations of different W42 mutant models. Our results suggest that substitution of W42 by small size and/or polar residues promotes HγDC denaturation due to the entry of water molecules into the hydrophobic core of the N-terminal domain. Similar behavior was observed in the C-terminal domain of HγDC when mutating the W130 residue located in a homologous position. Moreover, the exposure of the hydrophobic core residues could lead to the formation of aggregation-prone partially unfolded species. Overall, this study takes a step toward understanding the role of HγDC in cataract development.
Collapse
Affiliation(s)
- Rodrigo Aguayo-Ortiz
- Facultad de Química, Departamento de Fisicoquímica , Universidad Nacional Autónoma de México , Mexico City 04510 , Mexico.,Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Laura Dominguez
- Facultad de Química, Departamento de Fisicoquímica , Universidad Nacional Autónoma de México , Mexico City 04510 , Mexico
| |
Collapse
|
41
|
Abstract
The crystallins (α, β and γ), major constituent proteins of eye lens fiber cells play their critical role in maintaining the transparency and refractive index of the lens. Under different stress factors and with aging, β- and γ-crystallins start to unfold partially leading to their aggregation. Protein aggregation in lens basically enhances light scattering and causes the vision problem, commonly known as cataract. α-crystallin as a molecular chaperone forms complexes with its substrates (β- and γ-crystallins) to prevent such aggregation. In this chapter, the structural features of β- and γ-crystallins have been discussed. Detailed structural information linked with the high stability of γC-, γD- and γS-crystallins have been incorporated. The nature of homologous and heterologous interactions among crystallins has been deciphered, which are involved in their molecular association and complex formation.
Collapse
Affiliation(s)
- Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India.
| | - Priyanka Chauhan
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India
| |
Collapse
|
42
|
Altan I, Khan AR, James S, Quinn MK, McManus JJ, Charbonneau P. Using Schematic Models to Understand the Microscopic Basis for Inverted Solubility in γD-Crystallin. J Phys Chem B 2019; 123:10061-10072. [PMID: 31557434 DOI: 10.1021/acs.jpcb.9b07774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inverted solubility-melting a crystal by cooling-is observed in a handful of proteins, such as carbomonoxy hemoglobin C and γD-crystallin. In human γD-crystallin, the phenomenon is associated with the mutation of the 23rd residue, a proline, to a threonine, serine, or valine. One proposed microscopic mechanism entails an increase in surface hydrophobicity upon mutagenesis. Recent crystal structures of a double mutant that includes the P23T mutation allow for a more careful investigation of this proposal. Here, we first measure the surface hydrophobicity of various mutant structures of γD-crystallin and discern no notable increase in hydrophobicity upon mutating the 23rd residue. We then investigate the solubility inversion regime with a schematic patchy particle model that includes one of three variants of temperature-dependent patch energies: two of the hydrophobic effect, and one of a more generic nature. We conclude that, while solubility inversion due to the hydrophobic effect may be possible, microscopic evidence to support it in γD-crystallin is weak. More generally, we find that solubility inversion requires a fine balance between patch strengths and their temperature-dependent component, which may explain why inverted solubility is not commonly observed in proteins. We also find that the temperature-dependent interaction has only a negligible impact on liquid-liquid phase boundaries of γD-crystallin, in line with previous experimental observations.
Collapse
Affiliation(s)
| | - Amir R Khan
- School of Biochemistry and Immunology , Trinity College Dublin , Dublin , Ireland
| | - Susan James
- Department of Chemistry , Maynooth University , Maynooth , Ireland
| | - Michelle K Quinn
- Department of Chemistry , Maynooth University , Maynooth , Ireland
| | | | | |
Collapse
|
43
|
Roskamp KW, Kozlyuk N, Sengupta S, Bierma JC, Martin RW. Divalent Cations and the Divergence of βγ-Crystallin Function. Biochemistry 2019; 58:4505-4518. [PMID: 31647219 DOI: 10.1021/acs.biochem.9b00507] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The βγ-crystallin superfamily contains both β- and γ-crystallins of the vertebrate eye lens and the microbial calcium-binding proteins, all of which are characterized by a common double-Greek key domain structure. The vertebrate βγ-crystallins are long-lived structural proteins that refract light onto the retina. In contrast, the microbial βγ-crystallins bind calcium ions. The βγ-crystallin from the tunicate Ciona intestinalis (Ci-βγ) provides a potential link between these two functions. It binds calcium with high affinity and is found in a light-sensitive sensory organ that is highly enriched in metal ions. Thus, Ci-βγ is valuable for investigating the evolution of the βγ-crystallin fold away from calcium binding and toward stability in the apo form as part of the vertebrate lens. Here, we investigate the effect of Ca2+ and other divalent cations on the stability and aggregation propensity of Ci-βγ and human γS-crystallin (HγS). Beyond Ca2+, Ci-βγ is capable of coordinating Mg2+, Sr2+, Co2+, Mn2+, Ni2+, and Zn2+, although only Sr2+ is bound with comparable affinity to its preferred metal ion. The extent to which the tested divalent cations stabilize Ci-βγ structure correlates strongly with ionic radius. In contrast, none of the tested divalent cations improved the stability of HγS, and some of them induced aggregation. Zn2+, Ni2+, and Co2+ induce aggregation by interacting with cysteine residues, whereas Cu2+-mediated aggregation proceeds via a different binding site.
Collapse
Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Natalia Kozlyuk
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Suvrajit Sengupta
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Jan C Bierma
- Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
| | - Rachel W Martin
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States.,Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
| |
Collapse
|
44
|
Khan AR, James S, Quinn MK, Altan I, Charbonneau P, McManus JJ. Temperature-Dependent Interactions Explain Normal and Inverted Solubility in a γD-Crystallin Mutant. Biophys J 2019; 117:930-937. [PMID: 31422822 PMCID: PMC6731388 DOI: 10.1016/j.bpj.2019.07.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 11/30/2022] Open
Abstract
Protein crystal production is a major bottleneck in the structural characterization of proteins. To advance beyond large-scale screening, rational strategies for protein crystallization are crucial. Understanding how chemical anisotropy (or patchiness) of the protein surface, due to the variety of amino-acid side chains in contact with solvent, contributes to protein-protein contact formation in the crystal lattice is a major obstacle to predicting and optimizing crystallization. The relative scarcity of sophisticated theoretical models that include sufficient detail to link collective behavior, captured in protein phase diagrams, and molecular-level details, determined from high-resolution structural information, is a further barrier. Here, we present two crystal structures for the P23T + R36S mutant of γD-crystallin, each with opposite solubility behavior: one melts when heated, the other when cooled. When combined with the protein phase diagram and a tailored patchy particle model, we show that a single temperature-dependent interaction is sufficient to stabilize the inverted solubility crystal. This contact, at the P23T substitution site, relates to a genetic cataract and reveals at a molecular level the origin of the lowered and retrograde solubility of the protein. Our results show that the approach employed here may present a productive strategy for the rationalization of protein crystallization.
Collapse
Affiliation(s)
- Amir R Khan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Susan James
- Department of Chemistry, Maynooth University, Maynooth, Ireland
| | | | - Irem Altan
- Department of Chemistry, Duke University, Durham, North Carolina
| | | | | |
Collapse
|
45
|
Structural studies on the individual domains of human γS-crystallin and its G57W mutant unfolds mechanistic insights into childhood cataracts. Biochem Biophys Res Commun 2019; 517:499-506. [DOI: 10.1016/j.bbrc.2019.07.094] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 07/24/2019] [Indexed: 01/21/2023]
|
46
|
Wong EK, Prytkova V, Freites JA, Butts CT, Tobias DJ. Molecular Mechanism of Aggregation of the Cataract-Related γD-Crystallin W42R Variant from Multiscale Atomistic Simulations. Biochemistry 2019; 58:3691-3699. [PMID: 31393108 DOI: 10.1021/acs.biochem.9b00208] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The mechanisms leading to aggregation of the crystallin proteins of the eye lens remain largely unknown. We use atomistic multiscale molecular simulations to model the solution-state conformational dynamics of γD-crystallin and its cataract-related W42R variant at both infinite dilution and physiologically relevant concentrations. We find that the W42R variant assumes a distinct conformation in solution that leaves the Greek key domains of the native fold largely unaltered but lacks the hydrophobic interdomain interface that is key to the stability of wild-type γD-crystallin. At physiologically relevant concentrations, exposed hydrophobic regions in this alternative conformation become primary sites for enhanced interprotein interactions leading to large-scale aggregation.
Collapse
Affiliation(s)
- Eric K Wong
- Department of Chemistry , University of California , Irvine , California 92697 , United States
| | - Vera Prytkova
- Department of Chemistry , University of California , Irvine , California 92697 , United States
| | - J Alfredo Freites
- Department of Chemistry , University of California , Irvine , California 92697 , United States
| | - Carter T Butts
- Departments of Sociology, Electrical Engineering and Computer Science, and Statistics , University of California , Irvine , California 92697 , United States
| | - Douglas J Tobias
- Department of Chemistry , University of California , Irvine , California 92697 , United States
| |
Collapse
|
47
|
Aguayo-Ortiz R, González-Navejas A, Palomino-Vizcaino G, Rodriguez-Meza O, Costas M, Quintanar L, Dominguez L. Thermodynamic Stability of Human γD-Crystallin Mutants Using Alchemical Free-Energy Calculations. J Phys Chem B 2019; 123:5671-5677. [PMID: 31199646 DOI: 10.1021/acs.jpcb.9b01818] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
γD-Crystallin (HγDC) is a key structural protein in the human lens, whose aggregation has been associated with the development of cataracts. Single-point mutations and post-translational modifications destabilize HγDC interactions, forming partially folded intermediates, where hydrophobic residues are exposed and thus triggering its aggregation. In this work, we used alchemical free-energy calculations to predict changes in thermodynamic stability (ΔΔG) of 10 alanine-scanning variants and 12 HγDC mutations associated with the development of congenital cataract. Our results show that W42R is the most destabilizing mutation in HγDC. This has been corroborated through experimental determination of ΔΔG employing differential scanning calorimetry. Calculations of hydration free energies from the HγDC WT and the W42R mutant suggested that the mutant has a higher aggregation propensity. Our combined theoretical and experimental results contribute to understand HγDC destabilization and aggregation mechanisms in age-onset cataracts.
Collapse
Affiliation(s)
| | | | - Giovanni Palomino-Vizcaino
- Departamento de Química , Centro de Investigación y de Estudios Avanzados (Cinvestav) , Mexico City 07360 , Mexico
| | | | | | - Liliana Quintanar
- Departamento de Química , Centro de Investigación y de Estudios Avanzados (Cinvestav) , Mexico City 07360 , Mexico
| | | |
Collapse
|
48
|
Mills-Henry IA, Thol SL, Kosinski-Collins MS, Serebryany E, King JA. Kinetic Stability of Long-Lived Human Lens γ-Crystallins and Their Isolated Double Greek Key Domains. Biophys J 2019; 117:269-280. [PMID: 31266635 DOI: 10.1016/j.bpj.2019.06.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 05/25/2019] [Accepted: 06/05/2019] [Indexed: 12/17/2022] Open
Abstract
The γ-crystallins of the eye lens nucleus are among the longest-lived proteins in the human body. Synthesized in utero, they must remain folded and soluble throughout adulthood to maintain lens transparency and avoid cataracts. γD- and γS-crystallin are two major monomeric crystallins of the human lens. γD-crystallin is concentrated in the oldest lens fiber cells, the lens nucleus, whereas γS-crystallin is concentrated in the younger cells of the lens cortex. The kinetic stability parameters of these two-domain proteins and their isolated domains were determined and compared. Kinetic unfolding experiments monitored by fluorescence spectroscopy in varying concentrations of guanidinium chloride were used to extrapolate unfolding rate constants and half-lives of the crystallins in the absence of the denaturant. Consistent with their long lifespans in the lens, extrapolated half-lives for the initial unfolding step were on the timescale of years. Both proteins' isolated N-terminal domains were less kinetically stable than their respective C-terminal domains at denaturant concentrations predicted to disrupt the domain interface, but at low denaturant concentrations, the relative kinetic stabilities were reversed. Cataract-associated aggregation has been shown to proceed from partially unfolded intermediates in these proteins; their extreme kinetic stability likely evolved to protect the lens from the initiation of aggregation reactions. Our findings indicate that the domain interface is the source of significant kinetic stability. The gene duplication and fusion event that produced the modern two-domain architecture of vertebrate lens crystallins may be the origin of their high kinetic as well as thermodynamic stability.
Collapse
Affiliation(s)
- Ishara A Mills-Henry
- Department of Chemistry and Food Science, Framingham State University, Framingham, Massachusetts
| | | | | | - Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts.
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
| |
Collapse
|
49
|
Simultaneous induction of distinct protein phase separation events in multiple subcellular compartments of a single cell. Exp Cell Res 2019; 379:92-109. [DOI: 10.1016/j.yexcr.2019.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 02/18/2019] [Accepted: 03/05/2019] [Indexed: 01/31/2023]
|
50
|
Quinn MK, James S, McManus JJ. Chemical Modification Alters Protein-Protein Interactions and Can Lead to Lower Protein Solubility. J Phys Chem B 2019; 123:4373-4379. [PMID: 31046277 DOI: 10.1021/acs.jpcb.9b02368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The chemical modification of proteins is at the frontier of developments in biological imaging and biopharmaceutics. With the advent of more sensitive and higher resolution imaging techniques, researchers increasingly rely on the functionalization of proteins to enable these techniques to capture cellular processes. For biopharmaceutical therapies, chemically modified proteins, for example, antibody-drug conjugates (ADCs) offer the possibility of more tailored treatments for the disease with lower toxicities than traditional small molecule therapies. However, relatively little consideration is paid to how chemical modifications impact protein-protein interactions and solution stability. Using human γD-crystallin as a model, we demonstrate that chemical modification of the protein surface alters protein-protein interactions, which can result in lower solubility depending on the chemical nature of the modifier and the position on the protein where the modification is made. Understanding these effects is essential to ensure that modifying proteins effectively occurs with minimum self-association and that studies carried out using labeled proteins accurately reflect those of unmodified proteins.
Collapse
Affiliation(s)
- Michelle K Quinn
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
| | - Susan James
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
| | - Jennifer J McManus
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
| |
Collapse
|