The mechanism of the interaction of α-crystallin and UV-damaged βL-crystallin

alpha-Crystallin maintains the transparency of the lens by preventing the aggregation of damaged proteins. The aim of our work was to study the chaperone-like activity of native alpha-crystallin in near physiological conditions (temperature, ionic power, pH) using UV-damaged beta(L)-crystallin as the target protein. alpha-Crystallin in concentration depended manner inhibits the aggregation of UV-damaged beta(L)-crystallin. DSC investigation has shown that refolding of denatured UV-damaged beta(L)-crystallin was not observed under incubation with alpha-crystallin. alpha-Crystallin and UV-damaged beta(L)-crystallin form dynamic complexes with masses from 75 to several thousand kDa. The content of UV-damaged beta(L)-crystallin in such complexes increases with the mass of the complex. Complexes containing >10% of UV-damaged beta(L)-crystallin are prone to precipitation whereas those containing <10% of the target protein are relatively stable. Formation of a stable 75 kDa complex is indicative of alpha-crystallin dissociation. We suppose that alpha-crystallin dissociation is the result of an interaction of comparable amounts of the chaperone-like protein and the target protein. In the lens simultaneous damage of such amounts of protein, mainly beta and gamma-crystallins, is impossible. The authors suggest that in the lens rare molecules of the damaged protein interact with undissociated oligomers of alpha-crystallin, and thus preventing aggregation. (C) 2019 Elsevier B.V. All rights reserved.