PMID: 21516097

Authors:

Holdom MD, Davies AM, Nettleship JE, Bagby SC, Dhaliwal B, Girardi E, Hunt J, Gould HJ, Beavil AJ, McDonnell JM, Owens RJ, Sutton BJ

Title:

Conformational changes in IgE contribute to its uniquely slow dissociation rate from receptor FcvarepsilonRI.

Journal:

Nat Struct Mol Biol. 2011 May;18(5):571-6. Epub 2011 Apr 24.

Abstract:

Among antibody classes, IgE has a uniquely slow dissociation rate from, and high affinity for, its cell surface receptor FcvarepsilonRI. We show the structural basis for these key determinants of the ability of IgE to mediate allergic hypersensitivity through the 3.4-A-resolution crystal structure of human IgE-Fc (consisting of the Cvarepsilon2, Cvarepsilon3 and Cvarepsilon4 domains) bound to the extracellular domains of the FcvarepsilonRI alpha chain. Comparison with the structure of free IgE-Fc (reported here at a resolution of 1.9 A) shows that the antibody, which has a compact, bent structure before receptor engagement, becomes even more acutely bent in the complex. Thermodynamic analysis indicates that the interaction is entropically driven, which explains how the noncontacting Cvarepsilon2 domains, in place of the flexible hinge region of IgG antibodies, contribute together with the conformational changes to the unique binding properties of IgE.