1
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Serebryany E, Martin RW, Takahashi GR. The Functional Significance of High Cysteine Content in Eye Lens γ-Crystallins. Biomolecules 2024; 14:594. [PMID: 38786000 PMCID: PMC11118217 DOI: 10.3390/biom14050594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
Cataract disease is strongly associated with progressively accumulating oxidative damage to the extremely long-lived crystallin proteins of the lens. Cysteine oxidation affects crystallin folding, interactions, and light-scattering aggregation especially strongly due to the formation of disulfide bridges. Minimizing crystallin aggregation is crucial for lifelong lens transparency, so one might expect the ubiquitous lens crystallin superfamilies (α and βγ) to contain little cysteine. Yet, the Cys content of γ-crystallins is well above the average for human proteins. We review literature relevant to this longstanding puzzle and take advantage of expanding genomic databases and improved machine learning tools for protein structure prediction to investigate it further. We observe remarkably low Cys conservation in the βγ-crystallin superfamily; however, in γ-crystallin, the spatial positioning of Cys residues is clearly fine-tuned by evolution. We propose that the requirements of long-term lens transparency and high lens optical power impose competing evolutionary pressures on lens βγ-crystallins, leading to distinct adaptations: high Cys content in γ-crystallins but low in βB-crystallins. Aquatic species need more powerful lenses than terrestrial ones, which explains the high methionine content of many fish γ- (and even β-) crystallins. Finally, we discuss synergies between sulfur-containing and aromatic residues in crystallins and suggest future experimental directions.
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Affiliation(s)
- Eugene Serebryany
- Department of Physiology & Biophysics, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
- Laufer Center for Physical & Quantitative Biology, Stony Brook University, SUNY, Stony Brook, NY 11794, USA
| | - Rachel W. Martin
- Department of Chemistry, UCI Irvine, Irvine, CA 92697-2025, USA
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
| | - Gemma R. Takahashi
- Department of Molecular Biology & Biochemistry, UCI Irvine, Irvine, CA 92697-3900, USA
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2
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Savanagouder M, Mukku RP, Kiran U, Yeruva CV, Nagarajan N, Sharma Y, Raghunand TR. Dissecting the Ca 2+ dependence of DesA1 function in Mycobacterium tuberculosis. FEBS Lett 2024. [PMID: 38697952 DOI: 10.1002/1873-3468.14896] [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: 05/02/2023] [Revised: 11/04/2023] [Accepted: 02/28/2024] [Indexed: 05/05/2024]
Abstract
Mycobacterium tuberculosis (M. tb) has a complex cell wall, composed largely of mycolic acids, that are crucial to its structural maintenance. The M. tb desaturase A1 (DesA1) is an essential Ca2+-binding protein that catalyses a key step in mycolic acid biosynthesis. To investigate the structural and functional significance of Ca2+ binding, we introduced mutations at key residues in its Ca2+-binding βγ-crystallin motif to generate DesA1F303A, E304Q, and F303A-E304Q. Complementation of a conditional ΔdesA1 strain of Mycobacterium smegmatis, with the Ca2+ non-binders F303A or F303A-E304Q, failed to rescue its growth phenotype; these complements also exhibited enhanced cell wall permeability. Our findings highlight the criticality of Ca2+ in DesA1 function, and its implicit role in the maintenance of mycobacterial cellular integrity.
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Affiliation(s)
| | | | - Uday Kiran
- CSIR - Centre for Cellular and Molecular Biology, Hyderabad, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | | | | | - Yogendra Sharma
- CSIR - Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Tirumalai R Raghunand
- CSIR - Centre for Cellular and Molecular Biology, Hyderabad, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
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3
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Zhang Y, Ren L, Wu W, Liu J, Tian Q, Yao K, Yu Y, Hu L, Chen X. Cataract-causing variant Q70P damages structural stability of βB1-crystallin and increases its tendency to form insoluble aggregates. Int J Biol Macromol 2023; 242:124722. [PMID: 37148932 DOI: 10.1016/j.ijbiomac.2023.124722] [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: 11/16/2022] [Revised: 04/28/2023] [Accepted: 04/30/2023] [Indexed: 05/08/2023]
Abstract
Congenital cataract is the primary cause of childhood blindness worldwide. As the predominant structural protein, βB1-crystallin plays an important role in maintaining lens transparency and cellular homeostasis. Numerous cataract-causing mutations of βB1-crystallin have been identified with unclear pathogenic mechanism. We previously identified the mutation Q70P (Q to P at residue position 70) of βB1-crystallin linked to congenital cataract in a Chinese family. In this work, we investigated the potential molecular mechanism of βB1-Q70P in the congenital cataract at the molecular, protein, and cellular levels. We purified recombinant βB1 wild-type (WT) and Q70P proteins and compared their structural characteristics and biophysical properties by spectroscopic experiments under physiological temperature and environmental stresses (ultraviolet irradiation, heat stress, oxidative stress). Notably, βB1-Q70P significantly changed the structures of βB1-crystallin and exhibited lower solubility at physiological temperature. Meanwhile, βB1-Q70P was prone to aggregation in eukaryotic and prokaryotic cells, and was more sensitive to environmental stresses, along with impaired cellular viability. Furthermore, the molecular dynamics simulation indicated that the mutation Q70P damaged secondary structures and hydrogen bond network of βB1-crystallin, which were essential for the first Greek-key motif. This study delineated the pathological mechanism of βB1-Q70P and provided novel insights into treatment and prevention strategies for cataract-associated βB1 mutations.
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Affiliation(s)
- 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
| | - Ling Ren
- 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
| | - Jian Liu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Eye Center of Zhejiang Hospital, Zhejiang University School of Medicine, 12 Lingyin Road, Hangzhou 310012, 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
| | - Yibo Yu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China.
| | - Lidan Hu
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang Province 310052, China.
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310020, China.
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4
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Ren L, Hu L, Zhang Y, Liu J, Xu W, Wu W, Xu J, Chen X, Yao K, Yu Y. Cataract-Causing S93R Mutant Destabilized Structural Conformation of βB1 Crystallin Linking With Aggregates Formation and Cellular Viability. Front Mol Biosci 2022; 9:844719. [PMID: 35359596 PMCID: PMC8964140 DOI: 10.3389/fmolb.2022.844719] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/22/2022] [Indexed: 12/14/2022] Open
Abstract
Cataract, opacity of the eye lens, is the leading cause of visual impairment worldwide. The crucial pathogenic factors that cause cataract are misfolding and aggregation of crystallin protein. βB1‐crystallin, which is the most abundant water‐soluble protein in mammalian lens, is essential for lens transparency. A previous study identified the missense mutation βB1‐S93R being responsible for congenital cataract. However, the exact pathogenic mechanism causing cataract remains unclear. The S93 residue, which is located at the first Greek‐key motif of βB1‐crystallin, is highly conserved, and its substitution to Arginine severely impaired hydrogen bonds and structural conformation, which were evaluated via Molecular Dynamic Simulation. The βB1‐S93R was also found to be prone to aggregation in both human cell lines and Escherichia coli. Then, we isolated the βB1‐S93R variant from inclusion bodies by protein renaturation. The βB1-S93R mutation exposed more hydrophobic residues, and the looser structural mutation was prone to aggregation. Furthermore, the S93R mutation reduced the structural stability of βB1-crystallin when incubated at physiological temperature and made it more sensitive to environmental stress, such as UV irradiation or oxidative stress. We also constructed a βB1-S93R cellular model and discovered that βB1-S93R was more sensitive to environmental stress, causing not only aggregate formation but also cellular apoptosis and impaired cellular viability. All of the results indicated that lower solubility and structural stability, sensitivity to environmental stress, vulnerability to aggregation, and impaired cellular viability of βB1-S93R might be involved in cataract development.
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Affiliation(s)
- Ling Ren
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lidan Hu
- National Clinical Research Center for Child Health, The Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ying Zhang
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Liu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Eye Center of Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wanyue Xu
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Wu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Xiangjun Chen, ; Ke Yao, ; Yibo Yu,
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Xiangjun Chen, ; Ke Yao, ; Yibo Yu,
| | - Yibo Yu
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Xiangjun Chen, ; Ke Yao, ; Yibo Yu,
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5
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Patel S, Hosur RV. Replica exchange molecular dynamics simulations reveal self-association sites in M-crystallin caused by mutations provide insights of cataract. Sci Rep 2021; 11:23270. [PMID: 34857812 PMCID: PMC8639718 DOI: 10.1038/s41598-021-02728-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 11/09/2021] [Indexed: 11/09/2022] Open
Abstract
Crystallins are ubiquitous, however, prevalence is seen in eye lens. Eye lens crystallins are long-lived and structural intactness is required for maintaining lens transparency and protein solubility. Mutations in crystallins often lead to cataract. In this study, we performed mutations at specific sites of M-crystallin, a close homologue of eye lens crystallin and studied by using replica exchange molecular dynamics simulation with generalized Born implicit solvent model. Mutations were made on the Ca2+ binding residues (K34D and S77D) and in the hydrophobic core (W45R) which is known to cause congenital cataract in homologous γD-crystallin. The chosen mutations caused large motion of the N-terminal Greek key, concomitantly broke the interlocking Greek keys interactions and perturbed the compact core resulting in several folded and partially unfolded states. Partially unfolded states exposed large hydrophobic patches that could act as precursors for self-aggregation. Accumulation of such aggregates is the potential cause of cataract in homologous eye lens crystallins.
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Affiliation(s)
- Sunita Patel
- UM-DAE Centre for Excellence in Basic Sciences, Mumbai University Campus, Vidyanagari, Mumbai, 400098, India.
| | - Ramakrishna V. Hosur
- grid.452882.1UM-DAE Centre for Excellence in Basic Sciences, Mumbai University Campus, Vidyanagari, Mumbai, 400098 India
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6
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Rocha MA, Sprague-Piercy MA, Kwok AO, Roskamp KW, Martin RW. Chemical Properties Determine Solubility and Stability in βγ-Crystallins of the Eye Lens. Chembiochem 2021; 22:1329-1346. [PMID: 33569867 PMCID: PMC8052307 DOI: 10.1002/cbic.202000739] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Indexed: 11/10/2022]
Abstract
βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.
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Affiliation(s)
- Megan A. Rocha
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Marc A. Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| | - Ashley O. Kwok
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
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7
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Guilhen C, Lima WC, Ifrid E, Crespo-Yañez X, Lamrabet O, Cosson P. A New Family of Bacteriolytic Proteins in Dictyostelium discoideum. Front Cell Infect Microbiol 2021; 10:617310. [PMID: 33614529 PMCID: PMC7886984 DOI: 10.3389/fcimb.2020.617310] [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: 10/14/2020] [Accepted: 12/17/2020] [Indexed: 11/17/2022] Open
Abstract
Phagocytic cells ingest and destroy bacteria efficiently and in doing so ensure the defense of the human body against infections. Phagocytic Dictyostelium discoideum amoebae represent a powerful model system to study the intracellular mechanisms ensuring destruction of ingested bacteria in phagosomes. Here, we discovered the presence of a bacteriolytic activity against Klebsiella pneumoniae in cellular extracts from D. discoideum. The bacteriolytic activity was detected only at a very acidic pH mimicking the conditions found in D. discoideum phagosomes. It was also strongly decreased in extracts of kil1 KO cells that were previously described to kill inefficiently internalized bacteria, suggesting that the activity observed in vitro is involved in killing of bacteria in phagosomes. We purified a fraction enriched in bacteriolytic activity where only 16 proteins were detected and focused on four proteins selectively enriched in this fraction. Three of them belong to a poorly characterized family of D. discoideum proteins exhibiting a DUF3430 domain of unknown function and were named BadA (Bacteriolytic D. discoideum A), BadB, and BadC. We overexpressed the BadA protein in cells, and the bacteriolytic activity increased concomitantly in cell extracts. Conversely, depletion of BadA from cell extracts decreased significantly their bacteriolytic activity. Finally, in cells overexpressing BadA, bacterial killing was faster than in parental cells. Together these results identify BadA as a D. discoideum protein required for cellular bactericidal activity. They also define a new strategy to identify and characterize bactericidal proteins in D. discoideum cells.
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Affiliation(s)
- Cyril Guilhen
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Wanessa C Lima
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Estelle Ifrid
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Xenia Crespo-Yañez
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Otmane Lamrabet
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Pierre Cosson
- Department of Cell Physiology and Metabolism, Faculty of Medicine, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
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8
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Yang X, Xu J, Fu C, Jia Z, Yao K, Chen X. The cataract-related S39C variant increases γS-crystallin sensitivity to environmental stress by destroying the intermolecular disulfide cross-links. Biochem Biophys Res Commun 2020; 526:459-465. [DOI: 10.1016/j.bbrc.2020.03.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 03/11/2020] [Indexed: 02/06/2023]
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9
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Roskamp KW, Paulson CN, Brubaker WD, Martin RW. Function and Aggregation in Structural Eye Lens Crystallins. Acc Chem Res 2020; 53:863-874. [PMID: 32271004 DOI: 10.1021/acs.accounts.0c00014] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Crystallins are transparent, refractive proteins that contribute to the focusing power of the vertebrate eye lens. These proteins are extremely soluble and resist aggregation for decades, even under crowded conditions. Crystallins have evolved to avoid strong interprotein interactions and have unusual hydration properties. Crystallin aggregation resulting from mutation, damage, or aging can lead to cataract, a disease state characterized by opacity of the lens.Different aggregation mechanisms can occur, following multiple pathways and leading to aggregates with varied morphologies. Studies of variant proteins found in individuals with childhood-onset cataract have provided insight into the molecular factors underlying crystallin stability and solubility. Modulation of exposed hydrophobic surface is critical, as is preventing specific intermolecular interactions that could provide nucleation sites for aggregation. Biophysical measurements and structural biology techniques are beginning to provide a detailed picture of how crystallins crowd into the lens, providing high refractivity while avoiding excessively tight binding that would lead to aggregation.Despite the central biological importance of refractivity, relatively few experimental measurements have been made for lens crystallins. Our work and that of others have shown that hydration is important to the high refractive index of crystallin proteins, as are interactions between pairs of aromatic residues and potentially other specific structural features.This Account describes our efforts to understand both the functional and disease states of vertebrate eye lens crystallins, particularly the γ-crystallins. We use a variety of biophysical techniques, notably NMR spectroscopy, to investigate crystallin stability and solubility. In the first section, we describe efforts to understand the relative stability and aggregation propensity of different γS-crystallin variants. The second section focuses on interactions of these proteins with the holdase chaperone αB-crystallin. The third, fourth, and fifth sections explore different modes of aggregation available to crystallin proteins, and the final section highlights the importance of refractive index and the sometimes conflicting demands of selection for refractivity and solubility.
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Affiliation(s)
- Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Carolyn N. Paulson
- Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - William D. Brubaker
- SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025, 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
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10
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Honisch C, Donadello V, Hussain R, Peterle D, De Filippis V, Arrigoni G, Gatto C, Giurgola L, Siligardi G, Ruzza P. Application of Circular Dichroism and Fluorescence Spectroscopies To Assess Photostability of Water-Soluble Porcine Lens Proteins. ACS OMEGA 2020; 5:4293-4301. [PMID: 32149259 PMCID: PMC7057709 DOI: 10.1021/acsomega.9b04234] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/04/2020] [Indexed: 06/10/2023]
Abstract
The eye lens is mainly composed of the highly ordered water-soluble (WS) proteins named crystallins. The aggregation and insolubilization of these proteins lead to progressive lens opacification until cataract onset. Although this is a well-known disease, the mechanism of eye lens protein aggregation is not well understood; however, one of the recognized causes of proteins modification is related to the exposure to UV light. For this reason, the spectroscopic properties of WS lens proteins and their stability to UV irradiation have been evaluated by different biophysical methods including synchrotron radiation circular dichroism, fluorescence, and circular dichroism spectroscopies. Moreover, dynamic light scattering, gel electrophoresis, transmission electron microscopy, and protein digestion followed by tandem LC-MS/MS analysis were used to study the morphological and structural changes in protein aggregates induced by exposure to UV light. Our results clearly indicated that the exposure to UV radiation modified the protein conformation, inducing a loss of ordered structure and aggregation. Furthermore, we confirmed that these changes were attributable to the generation of reactive oxygen species due to the irradiation of the protein sample. This approach, involving the photodenaturation of proteins, provides a benchmark in high-throughput screening of small molecules suitable to prevent protein denaturation and aggregation.
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Affiliation(s)
- Claudia Honisch
- Institute
of Biomolecular Chemistry of CNR, Padua
Unit, 35131 Padova, Italy
- Department
of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Viola Donadello
- Institute
of Biomolecular Chemistry of CNR, Padua
Unit, 35131 Padova, Italy
| | - Rohanah Hussain
- Diamond
Light Source Ltd., Harwell Science and
Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Daniele Peterle
- Department
of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Vincenzo De Filippis
- Department
of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Giorgio Arrigoni
- Department
of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Proteomics
Center, University of Padova and Azienda
Ospedaliera di Padova, 35129 Padova, Italy
| | - Claudio Gatto
- Alchilife
Srl, R&D, Viale Austria
14, 35020 Ponte
San Nicolò (PD), Italy
| | - Laura Giurgola
- Alchilife
Srl, R&D, Viale Austria
14, 35020 Ponte
San Nicolò (PD), Italy
| | - Giuliano Siligardi
- Diamond
Light Source Ltd., Harwell Science and
Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Paolo Ruzza
- Institute
of Biomolecular Chemistry of CNR, Padua
Unit, 35131 Padova, Italy
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11
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Abstract
The crystallins (α, β and γ), major constituent proteins of eye lens fiber cells play their critical role in maintaining the transparency and refractive index of the lens. Under different stress factors and with aging, β- and γ-crystallins start to unfold partially leading to their aggregation. Protein aggregation in lens basically enhances light scattering and causes the vision problem, commonly known as cataract. α-crystallin as a molecular chaperone forms complexes with its substrates (β- and γ-crystallins) to prevent such aggregation. In this chapter, the structural features of β- and γ-crystallins have been discussed. Detailed structural information linked with the high stability of γC-, γD- and γS-crystallins have been incorporated. The nature of homologous and heterologous interactions among crystallins has been deciphered, which are involved in their molecular association and complex formation.
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Affiliation(s)
- Kalyan Sundar Ghosh
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India.
| | - Priyanka Chauhan
- Department of Chemistry, National Institute of Technology Hamirpur, Hamirpur, 177005, Himachal Pradesh, India
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12
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Krishnan B, Srivastava SS, Sankeshi V, Garg R, Srivastava S, Sankaranarayanan R, Sharma Y. βγ-Crystallination Endows a Novel Bacterial Glycoside Hydrolase 64 with Ca 2+-Dependent Activity Modulation. J Bacteriol 2019; 201:e00392-19. [PMID: 31527113 PMCID: PMC6832075 DOI: 10.1128/jb.00392-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 09/05/2019] [Indexed: 01/10/2023] Open
Abstract
The prokaryotic βγ-crystallins are a large group of uncharacterized domains with Ca2+-binding motifs. We have observed that a vast number of these domains are found appended to other domains, in particular, the carbohydrate-active enzyme (CAZy) domains. To elucidate the functional significance of these prospective Ca2+ sensors in bacteria and this widespread domain association, we have studied one typical example from Clostridium beijerinckii, a bacterium known for its ability to produce acetone, butanol, and ethanol through fermentation of several carbohydrates. This novel glycoside hydrolase of family 64 (GH64), which we named glucanallin, is composed of a βγ-crystallin domain, a GH64 domain, and a carbohydrate-binding module 56 (CBM56). The substrates of GH64, β-1,3-glucans, are the targets for industrial biofuel production due to their plenitude. We have examined the Ca2+-binding properties of this protein, assayed its enzymatic activity, and analyzed the structural features of the β-1,3-glucanase domain through its high-resolution crystal structure. The reaction products resulting from the enzyme reaction of glucanallin reinforce the mixed nature of GH64 enzymes, in contrast to the prevailing notion of them being an exotype. Upon disabling Ca2+ binding and comparing different domain combinations, we demonstrate that the βγ-crystallin domain in glucanallin acts as a Ca2+ sensor and enhances the glycolytic activity of glucanallin through Ca2+ binding. We also compare the structural peculiarities of this new member of the GH64 family to two previously studied members.IMPORTANCE We have biochemically and structurally characterized a novel glucanase from the less studied GH64 family in a bacterium significant for fermentation of carbohydrates into biofuels. This enzyme displays a peculiar property of being distally modulated by Ca2+ via assistance from a neighboring βγ-crystallin domain, likely through changes in the domain interface. In addition, this enzyme is found to be optimized for functioning in an acidic environment, which is in line with the possibility of its involvement in biofuel production. Multiple occurrences of a similar domain architecture suggest that such a "βγ-crystallination"-mediated Ca2+ sensitivity may be widespread among bacterial proteins.
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Affiliation(s)
- Bal Krishnan
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
- Indian Institute of Science Education and Research Berhampur, Odisha, India
| | | | - Venu Sankeshi
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Rupsi Garg
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | | | | | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
- Indian Institute of Science Education and Research Berhampur, Odisha, India
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13
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Abundant Perithecial Protein (APP) from Neurospora is a primitive functional analog of ocular crystallins. Biochem Biophys Res Commun 2019; 516:796-800. [PMID: 31255285 DOI: 10.1016/j.bbrc.2019.06.102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 06/18/2019] [Indexed: 11/21/2022]
Abstract
The eye arose during the Cambrian explosion from pre-existing proteins that would have been recruited for the formation of the specialized components of this organ, such as the transparent lens. Proteins suitable for the role of lens crystallins would need to possess unusual physical properties and the study of such earliest analogs of ocular crystallins would add to our understanding of the nature of recruitment of proteins as lens/corneal crystallins. We show that the Abundant Perithecial Protein (APP) of the fungi Neurospora and Sordaria fulfils the criteria for an early crystallin analog. The perithecia in these fungal species are phototropic, and APP accumulates at a high concentration in the neck of the pitcher-shaped perithecium. Spores are formed at the base of the perithecium, and light contributes to their maturation. The hydrodynamic properties of APP appear to exclude dimer formation or aggregation at high protein concentrations. APP is also deficient in Ca2+ binding, a property seen in its close homolog, the calcium-binding cell adhesion molecule (DdCAD-1) from Dictyostelium discoidum. Comparable to crystallins, APP occurs in high concentrations and seems to have dispensed with Ca2+ binding in exchange for greater stability. These crystallin-like attributes of APP lead us to demonstrate that it is a primitive form of ocular crystallins.
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Patel S, Krishnan B, Hosur RV, Chary KVR. Mechanistic Insights from Replica Exchange Molecular Dynamics Simulations into Mutation Induced Disordered-to-Ordered Transition in Hahellin, a βγ-Crystallin. J Phys Chem B 2019; 123:5086-5098. [DOI: 10.1021/acs.jpcb.9b03845] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Sunita Patel
- UM-DAE Centre for Excellence in Basic Sciences, Mumbai University Campus, Mumbai 400098, India
- Tata Institute of Fundamental Research, Hyderabad 500107, India
| | - Bal Krishnan
- Indian Institute of Science Education and Research, Berhampur, 760010, India
| | - Ramakrishna V. Hosur
- UM-DAE Centre for Excellence in Basic Sciences, Mumbai University Campus, Mumbai 400098, India
- Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Kandala V. R. Chary
- Tata Institute of Fundamental Research, Hyderabad 500107, India
- Tata Institute of Fundamental Research, Mumbai 400005, India
- Indian Institute of Science Education and Research, Berhampur, 760010, India
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15
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Zhang K, Zhao WJ, Yao K, Yan YB. Dissimilarity in the Contributions of the N-Terminal Domain Hydrophobic Core to the Structural Stability of Lens β/γ-Crystallins. Biochemistry 2019; 58:2499-2508. [PMID: 31037943 DOI: 10.1021/acs.biochem.8b01164] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Vertebrate lens β/γ-crystallins share a conserved tertiary structure consisting of four Greek-key motifs divided into two globular domains. Numerous inherited mutations in β/γ-crystallins have been linked to cataractogenesis. In this research, the folding mechanism underlying cataracts caused by the I21N mutation in βB2 was investigated by comparing the effect of mutagenesis on the structural features and stability of four β/γ-crystallins, βB1, βB2, γC, and γD. Our results showed that the four β/γ-crystallins differ greatly in solubility and stability against various stresses. The I21N mutation greatly impaired βB2 solubility and native structure as well as its stability against denaturation induced by guanidine hydrochloride, heat treatment, and ultraviolet irradiation. However, the deleterious effects were much weaker for mutations at the corresponding sites in βB1, γC, and γD. Molecular dynamics simulations indicated that the introduction of a nonnative hydrogen bond contributed to twisting Greek-key motif I outward, which might direct the misfolding of the I21N mutant of βB2. Meanwhile, partial hydration of the hydrophobic interior of the domain induced by the mutation destabilized βB1, γC, and γD. Our findings highlight the importance of nonnative hydrogen bond formation and hydrophobic core hydration in crystallin misfolding caused by inherited mutations.
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Affiliation(s)
- Kai Zhang
- Eye Center of the Second Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310009 , China
| | - Wei-Jie Zhao
- State Key Laboratory of Membrane Biology, School of Life Sciences , Tsinghua University , Beijing 100084 , China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, School of Medicine , Zhejiang University , Hangzhou 310009 , China
| | - Yong-Bin Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences , Tsinghua University , Beijing 100084 , China
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16
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Cerminati S, Paoletti L, Aguirre A, Peirú S, Menzella HG, Castelli ME. Industrial uses of phospholipases: current state and future applications. Appl Microbiol Biotechnol 2019; 103:2571-2582. [DOI: 10.1007/s00253-019-09658-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/18/2019] [Accepted: 01/23/2019] [Indexed: 12/18/2022]
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17
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Purification and Functional Characterization of the C-Terminal Domain of the β-Actin-Binding Protein AIM1 In Vitro. Molecules 2018; 23:molecules23123281. [PMID: 30544954 PMCID: PMC6320856 DOI: 10.3390/molecules23123281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 11/26/2018] [Accepted: 12/06/2018] [Indexed: 11/23/2022] Open
Abstract
The protein absent in melanoma 1 (AIM1) is a member of the βγ-crystal lens superfamily that is associated with the development of multiple cancers. The binding of AIM1 to β-actin affects the migration and invasion of prostate cancer epithelial cells. The C-terminus of AIM1 is required for the β-actin interaction. However, the characteristics of AIM1 in vitro and the interaction mode between AIM1 and β-actin remain unknown. We describe novel methods to prepare pure recombinant AIM1 and identify possible binding modes between AIM1 and β-actin; we also obtain the crystal of the first two βγ-crystallin domains of AIM1 (g1g2) for future structural biology research. We first express and purify AIM1 after cloning the sequence into a modified pET-28a_psp expression vector. Next, we define the minimum unit formed by the βγ-crystallin domain repeats that bound to β-actin and perform its physiological function. Finally, we made the structural model of the AIM1 g1g2 that can be used to guide future biomedical investigations and prostate cancer research.
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18
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Swaroop Srivastava S, Raman R, Kiran U, Garg R, Chadalawada S, Pawar AD, Sankaranarayanan R, Sharma Y. Interface interactions between βγ-crystallin domain and Ig-like domain render Ca 2+ -binding site inoperative in abundant perithecial protein of Neurospora crassa. Mol Microbiol 2018; 110:955-972. [PMID: 30216631 DOI: 10.1111/mmi.14130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2018] [Indexed: 11/30/2022]
Abstract
We describe a set of proteins in which a βγ-crystallin domain pairs with an Ig-like domain, and which are confined to microbes, like bacteria, slime molds and fungi. DdCAD-1 (Ca2+ -dependent cell adhesion molecule-1) and abundant perithecial protein (APP) represent this class of molecules. Using the crystal structure of APP-NTD (N-terminal domain of APP), we describe its mode of Ca2+ binding and provide a generalized theme for correct identification of the Ca2+ -binding site within this class of molecules. As a common feature, one of the two Ca2+ -binding sites is non-functional in the βγ-crystallin domains of these proteins. While APP-NTD binds Ca2+ with a micromolar affinity which is comparable to DdCAD-1, APP surprisingly does not bind Ca2+ . Crystal structures of APP and Ca2+ -bound APP-NTD reveal that the interface interactions in APP render its Ca2+ -binding site inoperative. Thus, heterodomain association provides a novel mode of Ca2+ -binding regulation in APP. Breaking the interface interactions (mutating Asp30Ala, Leu132Ala and Ile135Ala) or separation from the Ig-like domain removes the constraints upon the required conformational transition and enables the βγ-crystallin domain to bind Ca2+ . In mechanistic detail, our work demonstrates an interdomain interface adapted to distinct functional niches in APP and its homolog DdCAD-1.
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Affiliation(s)
| | - Rajeev Raman
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Uday Kiran
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Rupsi Garg
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Swathi Chadalawada
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Asmita D Pawar
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Rajan Sankaranarayanan
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Yogendra Sharma
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
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19
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Cerminati S, Paoletti L, Peirú S, Menzella HG, Castelli ME. The βγ-crystallin domain of Lysinibacillus sphaericus phosphatidylinositol phospholipase C plays a central role in protein stability. Appl Microbiol Biotechnol 2018; 102:6997-7005. [DOI: 10.1007/s00253-018-9136-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/25/2018] [Accepted: 05/23/2018] [Indexed: 10/14/2022]
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20
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Cvekl A, Zhao Y, McGreal R, Xie Q, Gu X, Zheng D. Evolutionary Origins of Pax6 Control of Crystallin Genes. Genome Biol Evol 2018; 9:2075-2092. [PMID: 28903537 PMCID: PMC5737492 DOI: 10.1093/gbe/evx153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 12/19/2022] Open
Abstract
The birth of novel genes, including their cell-specific transcriptional control, is a major source of evolutionary innovation. The lens-preferred proteins, crystallins (vertebrates: α- and β/γ-crystallins), provide a gateway to study eye evolution. Diversity of crystallins was thought to originate from convergent evolution through multiple, independent formation of Pax6/PaxB-binding sites within the promoters of genes able to act as crystallins. Here, we propose that αB-crystallin arose from a duplication of small heat shock protein (Hspb1-like) gene accompanied by Pax6-site and heat shock element (HSE) formation, followed by another duplication to generate the αA-crystallin gene in which HSE was converted into another Pax6-binding site. The founding β/γ-crystallin gene arose from the ancestral Hspb1-like gene promoter inserted into a Ca2+-binding protein coding region, early in the cephalochordate/tunicate lineage. Likewise, an ancestral aldehyde dehydrogenase (Aldh) gene, through multiple gene duplications, expanded into a multigene family, with specific genes expressed in invertebrate lenses (Ω-crystallin/Aldh1a9) and both vertebrate lenses (η-crystallin/Aldh1a7 and Aldh3a1) and corneas (Aldh3a1). Collectively, the present data reconstruct the evolution of diverse crystallin gene families.
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Affiliation(s)
- Ales Cvekl
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Rebecca McGreal
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Qing Xie
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York.,Department of Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - Xun Gu
- Program in Bioinformatics and Computational Biology, Department of Genetics, Development, and Cell Biology, Iowa State University
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York.,Department of Neurology, Albert Einstein College of Medicine, Bronx, New York.,Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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21
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Gao M, Yang F, Zhang L, Su Z, Huang Y. Exploring the sequence-structure-function relationship for the intrinsically disordered βγ-crystallin Hahellin. J Biomol Struct Dyn 2017; 36:1171-1181. [PMID: 28393629 DOI: 10.1080/07391102.2017.1316519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
βγ-Crystallins are a superfamily of proteins containing crystallin-type Greek key motifs. Some βγ-crystallin domains have been shown to bind Ca2+. Hahellin is a newly identified intrinsically disordered βγ-crystallin domain from Hahella chejuensis. It folds into a typical βγ-crystallin structure upon Ca2+ binding and acts as a Ca2+-regulated conformational switch. Besides Hahellin, another two putative βγ-crystallins from Caulobacter crescentus and Yersinia pestis are shown to be partially disordered in their apo-form and undergo large conformational changes upon Ca2+ binding, although whether they acquire a βγ-crystallin fold is not known. The extent of conformational disorder/order of a protein is determined by its amino acid sequence. To date how this sequence-structure relationship is reflected in the βγ-crystallin superfamily has not been investigated. In this work, we comparatively studied the sequence and structure of Hahellin with those of Protein S, an ordered βγ-crystallin, via various computational biophysical techniques. We found that several factors, including presence of a C-terminal disorder prone region, high content of energetic frustrations, and low contact density, may promote the formation of the disordered state of apo-Hahellin. We also analyzed the disorder propensities for other putative disordered βγ-crystallin domains. This study provides new clues for further understanding the sequence-structure-function relationship of βγ-crystallins.
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Affiliation(s)
- Meng Gao
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Fei Yang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Lei Zhang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Zhengding Su
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Yongqi Huang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
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22
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Srivastava SS, Jamkhindikar AA, Raman R, Jobby MK, Chadalawada S, Sankaranarayanan R, Sharma Y. A Transition Metal-Binding, Trimeric βγ-Crystallin from Methane-Producing Thermophilic Archaea, Methanosaeta thermophila. Biochemistry 2017; 56:1299-1310. [DOI: 10.1021/acs.biochem.6b00985] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Rajeev Raman
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Maroor K. Jobby
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Swathi Chadalawada
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Rajan Sankaranarayanan
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
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23
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Yeruva VC, Savanagouder M, Khandelwal R, Kulkarni A, Sharma Y, Raghunand TR. The Mycobacterium tuberculosis desaturase DesA1 (Rv0824c) is a Ca2+ binding protein. Biochem Biophys Res Commun 2016; 480:29-35. [DOI: 10.1016/j.bbrc.2016.10.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 10/25/2022]
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24
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Biophysical chemistry of the ageing eye lens. Biophys Rev 2015; 7:353-368. [PMID: 28510099 DOI: 10.1007/s12551-015-0176-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/23/2015] [Indexed: 12/24/2022] Open
Abstract
This review examines both recent and historical literature related to the biophysical chemistry of the proteins in the ageing eye, with a particular focus on cataract development. The lens is a vital component of the eye, acting as an optical focusing device to form clear images on the retina. The lens maintains the necessary high transparency and refractive index by expressing crystallin proteins in high concentration and eliminating all large cellular structures that may cause light scattering. This has the consequence of eliminating lens fibre cell metabolism and results in mature lens fibre cells having no mechanism for protein expression and a complete absence of protein recycling or turnover. As a result, the crystallins are some of the oldest proteins in the human body. Lack of protein repair or recycling means the lens tends to accumulate damage with age in the form of protein post-translational modifications. The crystallins can be subject to a wide range of age-related changes, including isomerisation, deamidation and racemisation. Many of these modification are highly correlated with cataract formation and represent a biochemical mechanism for age-related blindness.
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25
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Mishra A, Krishnan B, Raman R, Sharma Y. Ca2+ and βγ-crystallins: An affair that did not last? Biochim Biophys Acta Gen Subj 2015; 1860:299-303. [PMID: 26145580 DOI: 10.1016/j.bbagen.2015.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Revised: 06/25/2015] [Accepted: 06/29/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND During the last three decades, lens β- and γ-crystallins have found a huge number of kin from numerous taxonomical sources. Most of these proteins from invertebrates and microbes have been demonstrated or predicted to bind Ca2+ involving a distinct double-clamp motif, which is largely degenerated in lens homologues. SCOPE OF REVIEW The various aspects of transformation of βγ-crystallins from a quintessential Ca2+-binding protein into a primarily structural molecule have been reviewed. MAJOR CONCLUSIONS In lens members of βγ-crystallins, the residues involved in Ca2+ binding have diverged considerably from the classical consensus with consequent reduction in their Ca2+-binding properties. This evolutionary change is congenial to their new role as robust constituents of lens. The exact functions of the residual affinity for Ca2+ are yet to be established. GENERAL SIGNIFICANCE This review highlights the significance of reduction in Ca2+-binding ability of the βγ-crystallins for lens physiology and why this residual affinity may be functionally important. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Amita Mishra
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Bal Krishnan
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Rajeev Raman
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India
| | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India.
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26
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Vendra VPR, Khan I, Chandani S, Muniyandi A, Balasubramanian D. Gamma crystallins of the human eye lens. Biochim Biophys Acta Gen Subj 2015; 1860:333-43. [PMID: 26116913 DOI: 10.1016/j.bbagen.2015.06.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/08/2015] [Accepted: 06/19/2015] [Indexed: 01/12/2023]
Abstract
BACKGROUND Protein crystallins co me in three types (α, β and γ) and are found predominantly in the eye, and particularly in the lens, where they are packed into a compact, plastic, elastic, and transparent globule of proper refractive power range that aids in focusing incoming light on to the retina. Of these, the γ-crystallins are found largely in the nuclear region of the lens at very high concentrations (>400 mg/ml). The connection between their structure and inter-molecular interactions and lens transparency is an issue of particular interest. SCOPE OF REVIEW We review the origin and phylogeny of the gamma crystallins, their special structure involving the use of Greek key supersecondary structural motif, and how they aid in offering the appropriate refractive index gradient, intermolecular short range attractive interactions (aiding in packing them into a transparent ball), the role that several of the constituent amino acid residues play in this process, the thermodynamic and kinetic stability and how even single point mutations can upset this delicate balance and lead to intermolecular aggregation, forming light-scattering particles which compromise transparency. We cite several examples of this, and illustrate this by cloning, expressing, isolating and comparing the properties of the mutant protein S39C of human γS-crystallin (associated with congenital cataract-microcornea), with those of the wild type molecule. In addition, we note that human γ-crystallins are also present in other parts of the eye (e.g., retina), where their functions are yet to be understood. MAJOR CONCLUSIONS There are several 'crucial' residues in and around the Greek key motifs which are essential to maintain the compact architecture of the crystallin molecules. We find that a mutation that replaces even one of these residues can lead to reduction in solubility, formation of light-scattering particles and loss of transparency in the molecular assembly. GENERAL SIGNIFICANCE Such a molecular understanding of the process helps us construct the continuum of genotype-molecular structural phenotype-clinical (pathological) phenotype. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Venkata Pulla Rao Vendra
- Ophthalmic Molecular Genetics Section, National Eye Institute, Building 5635FL, Room 1S24, 5625 Fishers Lane, Rockville, MD 20852, United States.
| | - Ismail Khan
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad 500034 Telangana, India.
| | - Sushil Chandani
- Plot 32, LIC Colony, W Marredpally, Secunderabad 500026, Telangana, India.
| | - Anbukkarasi Muniyandi
- Department of Animal Science, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
| | - Dorairajan Balasubramanian
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad 500034 Telangana, India.
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