title: The human W42R γD-crystallin mutant structure provides a link between congenital and age-related cataracts.
abstract: Some mutants of human γD-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 γD-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 γD-crystallin. We solved the crystal structure of W42R at 1.7 Å 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 γD-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 γD-crystallin involved in age-related cataract.
authors.affiliation: School of Life Science and Biotechnology, Dalian University of Technology, Lingong Road, Dalian 116024, China.
authors.forename: Fangling
authors.initials: F
authors.lastname: Ji
authors.forename: Jinwon
authors.initials: J
authors.lastname: Jung
authors.forename: Leonardus M I
authors.initials: LM
authors.lastname: Koharudin
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
mesh_terms: D001703:Biophysics / Q000379:methods; D002386:Cataract / Q000151:congenital* / Q000235:genetics* / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D009154:Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014357:Trypsin / Q000737:chemistry; D038222:gamma-Crystallins / Q000737:chemistry* / Q000235:genetics*
chemical_list: C504903:CRYGD protein, human; D038222:gamma-Crystallins; D014357:Trypsin