An alternative structural isoform in amyloid-like aggregates formed from thermally denatured human γD-crystallin

TitleAn alternative structural isoform in amyloid-like aggregates formed from thermally denatured human γD-crystallin
Publication TypeJournal Article
Year of Publication2014
AuthorsMoran SD, Zhang TO, Zanni MT
Secondary TitleProtein Science
Volume23
Issue3
Pagination321–331
Date Published03/2014
Abstract

The eye lens protein γD-crystallin contributes to cataract formation in the lens. In vitro experiments show that γD-crystallin has a high propensity to form amyloid fibers when denatured, and that denaturation by acid or UV-B photodamage results in its C-terminal domain forming the β -sheet core of amyloid fibers. Here we show that thermal denaturation results in sheet-like aggregates that contain cross-linked oligomers of the protein, according to transmission electron microscopy and SDS-PAGE. We use two-dimensional infrared (2D IR) spectroscopy to show that these aggregates have an amyloid-like secondary structure with extended β -sheets, and use isotope dilution experiments to show that each protein contributes approximately one β -strand to each β -sheet in the aggregates. Using segmental 13C labeling, we show that the organization of the protein's two domains in thermally-induced aggregates results in a previously unobserved structure in which both the N-terminal and C-terminal domains contribute to β-sheets. We propose a model for the structural organization of the aggregates and attribute the recruitment of the NTD into the fiber structure to intermolecular cross linking.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/pro.2422/full
DOI10.1002/pro.2422
Short TitleProtein Science