HUMAN GAMMA-D CRYSTALLIN R58H MUTANT STRUCTURE AT 1.15 A RESOLUTION
[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.   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.  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.
[CRGD_HUMAN] Crystallins are the dominant structural components of the vertebrate eye lens.
Publication Abstract from PubMed
Several human cataracts have been linked to mutations in the gamma crystallin gene. One of these is the aculeiform cataract, which is caused by an R58H mutation in gammaD crystallin. We have shown previously that this cataract is caused by crystallization of the mutant protein, which is an order of magnitude less soluble than the wild-type. Here, we report the very high-resolution crystal structures of the mutant and wild-type proteins. Both proteins crystallize in the same space group and lattice. Thus, a strict comparison of the protein-protein and protein-water intermolecular interactions in the two crystal lattices is possible. Overall, the differences between the mutant and wild-type structures are small. At position 58, the mutant protein loses the direct ion-pair intermolecular interaction present in the wild-type, due to the differences between histidine and arginine at the atomic level; the interaction in the mutant is mediated by water molecules. Away from the mutation site, the mutant and wild-type lattice structures differ in the identity of side-chains that occupy alternate conformations. Since the interactions in the crystal phase are very similar for the two proteins, we conclude that the reduction in the solubility of the mutant is mainly due to the effect of the R58H mutation in the solution phase. The results presented here are also important as they are the first high-resolution X-ray structures of human gamma crystallins.
High-resolution X-ray crystal structures of human gammaD crystallin (1.25 A) and the R58H mutant (1.15 A) associated with aculeiform cataract.,Basak A, Bateman O, Slingsby C, Pande A, Asherie N, Ogun O, Benedek GB, Pande J J Mol Biol. 2003 May 16;328(5):1137-47. PMID:12729747
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.