Abstract
Purpose: :
To explore the nature of subunit exchange of α–crystallin and the effects of congenital cataract crystallin mutations.
Methods: :
Fluorescence resonance energy transfer (FRET) was measured and analyzed, using a fluorescent dye IANDANS–labeled W9F αA–crystallin as the acceptor probe and Trp in other crystallins (wild–type [WT] and R116C αA, WT and R120G αB, WT and Q155* ßB2) as the donor probe.
Results: :
The transfer efficiency, Föster distance, and average distance between two probes were obtained. A greater transfer efficiency was found for αA–αB than for αA–αA. R116C and R120G mutations decreased efficiency and increased distance between two probes for αA– and αB–crystallins, which arise from conformational changes. No transfer was observed between αA and either WT ßB2 or Q155* mutant.
Conclusions: :
The mechanism of subunit exchange is likely the reestablishing of equilibrium among various sizes of oligomers.
Keywords: protein structure/function • cataract • proteins encoded by disease genes