The human W42R ?D-crystallin mutant structure provides a link between congenital and age-related cataracts.

ABSTRACT: Some mutants of human ?D-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 ?D-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 ?D-crystallin. We solved the crystal structure of W42R at 1.7 ? 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 ?D-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 ?D-crystallin involved in age-related cataract.

SUBMITTER: Ji F 

PROVIDER: S-EPMC3537076 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature