alpha-Crystallin acting as a molecular chaperonin against photodamage by UV irradiation.
alpha-Crystallin, a major protein of the eye lens, is known to have chaperone activity in preventing heat-induced aggregation of enzymes and other crystallins. In this study, we investigate the ability of alpha-crystallin to inhibit UV-light-induced aggregation of other lens proteins and the effect of exposure of alpha-crystallin to UV irradiation on its chaperone activity. The chaperone activities of alpha-crystallin preincubated at different temperatures were found to be different and could be correlated with its change in quaternary structure as determined by the fluorescence probe ANS (8-anilo-1-naphthalene sulfonate). alpha-Crystallin can inhibit the aggregation of gamma-crystallin from UV irradiation at room temperature, and the preheated alpha-crystallins provide more protection than the native one. Upon irradiation by UV light, alpha-crystallin gradually lost its ability to protect beta-crystallin against thermal aggregation. The loss of the chaperone efficacy of alpha-crystallin to protect other lens proteins may shed light on human cataract formation induced by long-term exposure to UV irradiation.
Lee
J S
JS
Department of Ophthalmology, Chang-Gung Memorial Hospital, Taipei, Taiwan.
Liao
J H
JH
Wu
S H
SH
Chiou
S H
SH
D000817:Anilino Naphthalenesulfonates / Q000032:analysis; D000818:Animals; D003459:Crystallins / Q000187:drug effects / Q000378:metabolism* / Q000494:pharmacology / Q000528:radiation effects; D005456:Fluorescent Dyes; D006361:Heating / Q000009:adverse effects; D006801:Humans; D018832:Molecular Chaperones / Q000378:metabolism* / Q000494:pharmacology / Q000528:radiation effects; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects / Q000528:radiation effects; D013552:Swine; D014466:Ultraviolet Rays / Q000009:adverse effects*
D000817:Anilino Naphthalenesulfonates; D003459:Crystallins; D005456:Fluorescent Dyes; D018832:Molecular Chaperones; C027132:1-anilino-8-naphthalenesulfonate