The impact of hydrogen peroxide on structure, stability and functional properties of human R12C mutant αA-crystallin: the imperative insights into pathomechanism of the associated congenital cataract incidence

The oxidative stress in eye lens which occurs during inflammation and under chronic hyperglycemia has been already indicated in the pathogenesis of cataract disorders. The aim of this study was to examine structural and functional properties of R12C mutant αA-Crystallin (αA-Cry) in the presence of hydrogen peroxide. The study was done using different spectroscopic techniques and gel mobility shift assay. According to results of our study, H2O2 oxidation strongly compromises the chaperone function of the R12C mutant but not of wild-type αA-Cry. Also, it affects the structural properties of both wild-type and mutant proteins, albeit to different degree. The H2O2 exposure promotes extensive disulfide mediated oligomerization of the R12C mutant but not of the wild-type as revealed by gel mobility shift assay and dynamic light scattering. Moreover, in the presence of hydrogen peroxide, the mutant protein demonstrates severe conformational and protease instability and increased amyloidogenic propensity. The obtained results suggest that incubation of R12C mutant recombinant αA-Cry with hydrogen peroxide accelerates the molecular events which have been already implicated in the pathomechanism of cataract development. Taken together these results suggest that individuals carrying the R12C mutation are at an increased risk to develop early-onset cataract under condition of oxidative stress.