Abstract
Abstract: :
Purpose: To determine the effect of deamidation on the structure and association of betaB1 crystallin. Aggregation of crystallin proteins in the vertebrate lens is a factor in congenital and age–related cataract. Deamidation is a prevalent modification, but the effect of specific sites of deamidation on crystallin stability in vivo is not known. Methods: Using mass spectrometry, a previously unreported deamidation in betaB1 crystallin was identified at Gln146. Static and quasi–elastic laser light scattering, circular dichroism, and heat aggregation studies were used to explore the structure and associative properties of recombinantly expressed wild type (Wt) betaB1 and the deamidated betaB1 mutant, Q146E. Results: Dimer formation occurred for Wt betaB1 and Q146E, in a concentration–dependent manner, but only Q146E showed formation of higher–ordered oligomers at the concentrations studied. Deamidation at Gln146 led to an increased tendency of betaB1 to aggregate upon heating. Conclusions: We conclude that deamidation creates unique effects depending upon where the deamidation is introduced in the crystallin structure.
Keywords: crystallins • protein modifications–post translational • protein structure/function