Structure, Chaperone Activity, and Aggregation of Wild-Type and R12C Mutant αB-Crystallins in the Presence of Thermal Stress and Calcium Ion - Implications for Role of Calcium in Cataract Pathogenesis.
The current study was performed with the aim to evaluate the chaperoning ability, structural features, and aggregation propensity of wild-type and R12C mutant αB-crystallins (αB-Cry) under thermal stress and in the presence of calcium ion. The results of different spectroscopic analyses suggest that wild-type and mutant αB-Cry have dissimilar secondary and tertiary structures. Moreover, αB-Cry indicates slightly improved chaperone activity upon the R12C mutation. Thermal stress and calcium, respectively, enhance and reduce the extent of solvent-exposed hydrophobic surfaces accompanying formation of ordered and non-ordered aggregate entities in both proteins. Compared to the wild-type protein, the R12C mutant counterpart shows significant resistance against thermal and calcium-induced aggregation. In addition, in the presence of calcium, significant structural variation was accompanied by reduction in the solvent-exposed hydrophobic patches and attenuation of chaperone activity in both proteins. Additionally, gel mobility shift assay indicates the intrinsic propensity of R12C mutant αB-Cry for disulfide bridge-mediated protein dimerization. Overall, the results of this study are of high significance for understanding the molecular details of different factors that are involved in the pathomechanism of cataract disorders.
Shiraz University, Protein Chemistry Laboratory (PCL), Department of Biology, Shiraz, 71345, Iran. ryousefi@shirazu.ac.ir.
M Ragerdi
MR
Kashani
R
R
Yousefi
M
M
Akbarian
M M
MM
Alavianmehr
Y
Y
Ghasemi
D019943:Amino Acid Substitution; D002118:Calcium / Q000378:metabolism; D002386:Cataract / Q000235:genetics* / Q000473:pathology*; D006358:Hot Temperature; D006801:Humans; D017354:Point Mutation; D038203:alpha-Crystallin B Chain / Q000235:genetics* / Q000378:metabolism*
D038203:alpha-Crystallin B Chain; D002118:Calcium