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The congenital cataract-linked G61C mutation destabilizes γD-crystallin and promotes non-native aggregation.

Zhang W, Cai HC, Li FF, Xi YB, Ma X, Yan YB - PLoS ONE (2011)

Bottom Line: The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding.The aggregation-prone property of the mutant was not altered by the addition of reductive reagent.These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
γD-crystallin is one of the major structural proteins in human eye lens. The solubility and stability of γD-crystallin play a crucial role in maintaining the optical properties of the lens during the life span of an individual. Previous study has shown that the inherited mutation G61C results in autosomal dominant congenital cataract. In this research, we studied the effects of the G61C mutation on γD-crystallin structure, stability and aggregation via biophysical methods. CD, intrinsic and extrinsic fluorescence spectroscopy indicated that the G61C mutation did not affect the native structure of γD-crystallin. The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding. The mutation mainly affected the transition from the native state to the intermediate but not that from the intermediate to the unfolded or aggregated states. At high temperatures, both proteins were able to form aggregates, and the aggregation of the mutant was much more serious than the wild type protein at the same temperature. At body temperature and acidic conditions, the mutant was more prone to form amyloid-like fibrils. The aggregation-prone property of the mutant was not altered by the addition of reductive reagent. These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation.

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Crystal structure of human γD-crystallin (PDB ID: 1HK0).The position of G61 is highlighted by space filling model. N and C represent the N- and C-terminus of the protein.
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pone-0020564-g001: Crystal structure of human γD-crystallin (PDB ID: 1HK0).The position of G61 is highlighted by space filling model. N and C represent the N- and C-terminus of the protein.

Mentions: In human lens, γC- and γD-crystallins are expressed at the highest level among the γ-crystallins (about 80%) [14]. Consequently, autosomal dominant congenital cataract has also been reported to be caused by many inherited mutations in γD-crystallin [15]–[33]. γD-crystallin is a monomeirc protein composed of four Greek-key β-sheet structure (Figure 1) [34]. The γD-crystallin mutations may result in inherited cataract by different molecular mechanisms including altering the native structure, decreasing the stability of the native protein, promoting aggregation and/or increasing its sensitivity of UV light. Although most mutations in γD-crystallin are associated with the phenotype of nuclear cataract, the actual mechanism may differ from case to case depending on the role of the mutated residue in γD-crystallin structure and stability and the nature of the substituted residue. Recently, a newly characterized congenital mutation G61C in γD-crystallin has been reported to associate with an irregular phenotype of coralliform cataract [35]. In this research, we studied the effects of the mutation G61C on γD-crystallin structure, stability and aggregation, and the results herein suggested that the decrease in γD-crystallin stability against stresses might contributes to the onset of cataract through protein aggregation.


The congenital cataract-linked G61C mutation destabilizes γD-crystallin and promotes non-native aggregation.

Zhang W, Cai HC, Li FF, Xi YB, Ma X, Yan YB - PLoS ONE (2011)

Crystal structure of human γD-crystallin (PDB ID: 1HK0).The position of G61 is highlighted by space filling model. N and C represent the N- and C-terminus of the protein.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105094&req=5

pone-0020564-g001: Crystal structure of human γD-crystallin (PDB ID: 1HK0).The position of G61 is highlighted by space filling model. N and C represent the N- and C-terminus of the protein.
Mentions: In human lens, γC- and γD-crystallins are expressed at the highest level among the γ-crystallins (about 80%) [14]. Consequently, autosomal dominant congenital cataract has also been reported to be caused by many inherited mutations in γD-crystallin [15]–[33]. γD-crystallin is a monomeirc protein composed of four Greek-key β-sheet structure (Figure 1) [34]. The γD-crystallin mutations may result in inherited cataract by different molecular mechanisms including altering the native structure, decreasing the stability of the native protein, promoting aggregation and/or increasing its sensitivity of UV light. Although most mutations in γD-crystallin are associated with the phenotype of nuclear cataract, the actual mechanism may differ from case to case depending on the role of the mutated residue in γD-crystallin structure and stability and the nature of the substituted residue. Recently, a newly characterized congenital mutation G61C in γD-crystallin has been reported to associate with an irregular phenotype of coralliform cataract [35]. In this research, we studied the effects of the mutation G61C on γD-crystallin structure, stability and aggregation, and the results herein suggested that the decrease in γD-crystallin stability against stresses might contributes to the onset of cataract through protein aggregation.

Bottom Line: The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding.The aggregation-prone property of the mutant was not altered by the addition of reductive reagent.These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
γD-crystallin is one of the major structural proteins in human eye lens. The solubility and stability of γD-crystallin play a crucial role in maintaining the optical properties of the lens during the life span of an individual. Previous study has shown that the inherited mutation G61C results in autosomal dominant congenital cataract. In this research, we studied the effects of the G61C mutation on γD-crystallin structure, stability and aggregation via biophysical methods. CD, intrinsic and extrinsic fluorescence spectroscopy indicated that the G61C mutation did not affect the native structure of γD-crystallin. The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding. The mutation mainly affected the transition from the native state to the intermediate but not that from the intermediate to the unfolded or aggregated states. At high temperatures, both proteins were able to form aggregates, and the aggregation of the mutant was much more serious than the wild type protein at the same temperature. At body temperature and acidic conditions, the mutant was more prone to form amyloid-like fibrils. The aggregation-prone property of the mutant was not altered by the addition of reductive reagent. These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation.

Show MeSH
Related in: MedlinePlus