RT Journal Article
SR Electronic
T1 Cataract-associated deamidations on the surface of γS-crystallin increase protein unfolding and flexibility at distant regions
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 646083
DO 10.1101/646083
A1 Heather M. Forsythe
A1 Calvin Vetter
A1 Kayla Ann Jara
A1 Patrick N. Reardon
A1 Larry L. David
A1 Elisar J. Barbar
A1 Kirsten J. Lampi
YR 2019
UL http://biorxiv.org/content/early/2019/05/22/646083.abstract
AB Deamidation is a major age-related modification in the human lens that is highly prevalent in crystallins isolated from cataractous lenses. However, the mechanism by which deamidation causes proteins to become insoluble is not known, because of only subtle structural changes observed in vitro. We have identified Asn14 and Asn76 of γS-crystallin as highly deamidated in insoluble proteins. These sites are on the surface of the N-terminal domain and were mimicked by replacing the Asn with Asp residues. We used heteronuclear NMR spectroscopy to measure their amide hydrogen exchange and 15N relaxation dynamics to identify regions with significantly increased dynamics compared to wildtype-γS. Changes in dynamics were localized to the C-terminal domain, particularly to helix and surface loops distant from the mutation sites. Thus, a potential mechanism for γS deamidation-induced insolubilization in cataractous lenses is altered dynamics due to local regions of unfolding and increased flexibility.