4gr7
From Proteopedia
The human W42R Gamma D-Crystallin Mutant Structure at 1.7A Resolution
Structural highlights
Disease[CRGD_HUMAN] Defects in CRYGD are a cause of cataract autosomal dominant (ADC) [MIM:604219]. Cataract is an opacification of the crystalline lens of the eye that frequently results in visual impairment or blindness. Opacities vary in morphology, are often confined to a portion of the lens, and may be static or progressive. In general, the more posteriorly located and dense an opacity, the greater the impact on visual function. Cataract is the most common treatable cause of visual disability in childhood.[1] [2] [3] Defects in CRYGD are the cause of cataract congenital non-nuclear polymorphic autosomal dominant (CCP) [MIM:601286]; also known as polymorphic congenital cataract. A congenital cataract characterized by a non-progressive phenotype and partial opacity that has a variable location between the fetal nucleus of the lens and the equator. The fetal nucleus is normal. The opacities are irregular and look similar to a bunch of grapes and may be present simultaneously in different lens layers.[4] [5] Defects in CRYGD are the cause of cataract congenital cerulean type 3 (CCA3) [MIM:608983]; also known as congenital cataract blue dot type 3. A cerulean form of autosomal dominant congenital cataract. Cerulean cataract is characterized by peripheral bluish and white opacifications organized in concentric layers with occasional central lesions arranged radially. The opacities are observed in the superficial layers of the fetal nucleus as well as the adult nucleus of the lens. Involvement is usually bilateral. Visual acuity is only mildly reduced in childhood. In adulthood, the opacifications may progress, making lens extraction necessary. Histologically the lesions are described as fusiform cavities between lens fibers which contain a deeply staining granular material. Although the lesions may take on various colors, a dull blue is the most common appearance and is responsible for the designation cerulean cataract. Defects in CRYGD are the cause of cataract crystalline aculeiform (CACA) [MIM:115700]. A congenital crystalline cataract characterized by fiberglass-like or needle-like crystals projecting in different directions, through or close to the axial region of the lens. The opacity causes a variable degree of vision loss.[6] Function[CRGD_HUMAN] Crystallins are the dominant structural components of the vertebrate eye lens. Publication Abstract from PubMedSome mutants of human gammaD-crystallin are closely linked to congenital cataracts, although the detailed molecular mechanisms of mutant-associated cataract formation are generally not known. Here we report on a recently discovered gammaD-crystallin mutant (W42R) that has been linked to autosomal dominant, congenital cataracts in a Chinese family. The mutant protein is much less soluble and stable than wild-type gammaD-crystallin. We solved the crystal structure of W42R at 1.7 A resolution, which revealed only minor differences from the wild-type structure. Interestingly, the W42R variant is highly susceptible to protease digestion, suggesting the presence of a small population of partially unfolded protein. This partially unfolded species was confirmed and quantified by NMR spectroscopy. Hydrogen/deuterium exchange experiments revealed chemical exchange between the folded and unfolded species. Exposure of wild-type gammaD-crystallin to UV caused damage to the N-terminal domain of the protein, resulting in very similar proteolytic susceptibility as observed for the W42R mutant. Altogether, our combined data allowed us to propose a model for W42R pathogenesis, with the W42R mutant serving as a mimic for photodamaged gammaD-crystallin involved in age-related cataract. The human W42R gammaD-crystallin mutant structure provides a link between congenital and age-related cataracts.,Ji F, Jung J, Koharudin LM, Gronenborn AM J Biol Chem. 2013 Jan 4;288(1):99-109. doi: 10.1074/jbc.M112.416354. Epub 2012, Nov 2. PMID:23124202[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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