Dataset Information

The mutation V42M distorts the compact packing of the human gamma-S-crystallin molecule, resulting in congenital cataract.

ABSTRACT:

Background

Human ?S-crystallin is an important component of the human eye lens nucleus and cortex. The mutation V42M in the molecule causes severe congenital cataract in children. We compare the structure of the mutant protein with that of the wild type in order to understand how structural changes in the mutant relate to the mechanism of opacification.

Methods

Both proteins were made using conventional cloning and expression procedures. Secondary and tertiary structural features of the proteins were analyzed using spectral methods. Structural stabilities of the proteins were analyzed using chemical and thermal denaturation methods. Self-aggregation was monitored using extrinsic spectral probes. Molecular modeling was used to compare the structural features of the two proteins.

Results

While the wild type and mutant have the same secondary structure, molecular modeling and fluorescence analysis suggest the mutant to have a more open tertiary structure, with a larger hydrophobic surface. Experiments using extrinsic probes reveal that the mutant readily self-aggregates, with the suggestion that the aggregates might be similar to amyloidogenic fibrils. Chemical denaturation indicates that while the wild type exhibits the classic two-state transition, V42M goes through an intermediate state, and has a distinctly lower stability than the wild type. The temperature of thermal unfolding of the mutant is also distinctly lower. Further, the mutant readily precipitates and scatters light more easily than the wild type.

Conclusion

The replacement of valine in position 42 by the longer and bulkier methionine in human ?S-crystallin perturbs the compact ?-sheet core packing topology in the N-terminal domain of the molecule, exposes nonpolar residues thereby increasing the surface hydrophobicity and weakens the stability of the protein, thus promoting self-aggregation leading to light scattering particles. This set of changes in the properties of the mutant offers a molecular insight into the mechanism of opacification.

SUBMITTER: Vendra VP

PROVIDER: S-EPMC3528740 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Publications

The mutation V42M distorts the compact packing of the human gamma-S-crystallin molecule, resulting in congenital cataract.

Vendra Venkata Pulla Rao VP Chandani Sushil S Balasubramanian Dorairajan D

PloS one 20121221 12

<h4>Background</h4>Human γS-crystallin is an important component of the human eye lens nucleus and cortex. The mutation V42M in the molecule causes severe congenital cataract in children. We compare the structure of the mutant protein with that of the wild type in order to understand how structural changes in the mutant relate to the mechanism of opacification.<h4>Methods</h4>Both proteins were made using conventional cloning and expression procedures. Secondary and tertiary structural features ...[more]

PMID: 23284690

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Project description:PURPOSE: To identify the underlying genetic defect in a north Indian family with seven members in three-generations affected with bilateral congenital cataract. METHODS: Detailed family history and clinical data were recorded. Linkage analysis using fluorescently labeled microsatellite markers for the already known candidate gene loci was performed in combination with mutation screening by bidirectional sequencing. RESULTS: Affected individuals had bilateral congenital cataract. Cataract was of opalescent type with the central nuclear region denser than the periphery. Linkage was excluded for the known cataract candidate gene loci at 1p34-36, 1q21-25 (gap junction protein, alpha 8 [GJA8]), 2q33-36 (crystallin, gamma A [CRYGA], crystallin, gamma B [CRYGB], crystallin, gamma C [CRYGC], crystallin, gamma D [CRYGD], crystallin, beta A2 [CRYBA2]), 3q21-22 (beaded filament structural protein 2, phakinin [BFSP2]), 12q12-14 (aquaporin 0 [AQP0]), 13q11-13 (gap junction protein, alpha 3 [GJA3]), 15q21-22, 16q22-23 (v-maf musculoaponeurotic fibrosarcoma oncogene homolog [MAF], heat shock transcription factor 4 [HSF4]), 17q11-12 (crystallin, beta A1 [CRYBA1]), 17q24, 21q22.3 (crystallin, alpha A [CRYAA]), and 22q11.2 (crystallin, beta B1 [CRYBB1], crystallin, beta B2 [CRYBB2], crystallin, beta B3 [CRYBB3], crystallin, beta A4 [CRYBA4]). Crystallin, alpha B (CRYAB) at chromosome 11q23-24 was excluded by sequence analysis. However, sequencing the candidate gene, crystallin, gamma S (CRYGS), at chromosome 3q26.3-qter showed a heterozygous c.176G-->A change that resulted in the replacement of a structurally highly conserved valine by methionine at codon 42 (p.V42M). This sequence change was not observed in unaffected family members or in the 100 ethnically matched controls. CONCLUSIONS: We report a novel missense mutation, p.V42M, in CRYGS associated with bilateral congenital cataract in a family of Indian origin. This is the third report of a mutation in this exceptional member of the beta-/gamma-crystallin superfamily and further substantiates the genetic and clinical heterogeneity of autosomal dominant cataract.

Dataset Information

The mutation V42M distorts the compact packing of the human gamma-S-crystallin molecule, resulting in congenital cataract.

Background

Methods

Results

Conclusion

Publications

The mutation V42M distorts the compact packing of the human gamma-S-crystallin molecule, resulting in congenital cataract.

Similar Datasets

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