Purchase this article with an account.
K. J. Lampi, M. Michiel, T. Takata, E. Duprat, F. Skouri-Panet, S. Finet, A. Tardieu; Deamidation Induces Local Structural Changes in BetaB2 and BetaA3-Crystallins That Disrupt Stabilizing Interactions With Other Crystallins. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5801.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine how deamidation-induced changes in beta-crystallin structure alter interactions among crystallins and with the chaperone, alphaA-crystallin.
Deamidation was mimicked by replacing glutamines with glutamic acids located at the monomer-monomer interface of the betaB2 and betaA3-crystallin homodimers. Deamidation-induced local structural changes were identified using hydrogen/deuterium exchange with electrospray ionization source mass spectrometry (HDMS). These changes were then correlated to stability during thermal unfolding and aggregation detected by dynamic light scattering. The chaperone requirement of deamidated betaB2-crystallin was determined using alpha-crystallin. The protective interaction of betaB1 with betaA3 was also determined.
HDMS revealed differences in deuterium incorporation between regions of wild type βB2-crystallin (WT), suggesting that the N-terminal domain (N-td) of βB2 was more accessible in solution than the C-terminal domain (C-td). Introducing glutamates at the interface decreased deuterium incorporation in the N-td and increased deuterium incorporation near the site of mutation in the C-td.Deamidation at both interface Gln residues or at Q70, but not Q162, significantly lowered the temperature for unfolding and aggregation, which was rapidly followed by precipitation. This deamidation-induced aggregation and precipitation was not completely prevented by alpha-crystallin chaperone.Deamidation at the interface in betaA3 disrupted the linker peptide between the domains and altered the interaction sites with betaB1-crystallin.
Local structural changes due to deamidation were identified. These structural changes led to decreased stability and to altered interactions with other crystallins, including the protective chaperone, alpha-crystallin. A potential mechanism for cataract formation in vivo may involve accumulation of deamidated β-crystallin aggregates partially due to disruption of the stabilizing crystallin-crystallin interactions.
This PDF is available to Subscribers Only