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A crystallin fold in the interleukin-4-inducing principle of Schistosoma mansoni eggs (IPSE/alpha-1) mediates IgE binding for antigen-independent basophil activation.
J. Biol. Chem. 290, 22111-22126 (2015)
IPSE/alpha-1, the major secretory product of eggs from the parasitic worm Schistosoma mansoni, efficiently triggers basophils to release the immunomodulatory key cytokine interleukin-4. Activation by IPSE/alpha-1 requires the presence of IgE on the basophils, but the detailed molecular mechanism underlying activation is unknown. NMR and crystallographic analysis of IPSEδNLS, a monomeric IPSE/alpha-1 mutant, revealed that IPSE/alpha-1 is a new member of the β&]gamma]-crystallin superfamily. We demonstrate that this molecule is a general immunoglobulin-binding factor with highest affinity for IgE. NMR binding studies of IPSEδNLS with the 180-kDa molecule IgE identified a large positively charged binding surface that includes a flexible loop, which is unique to the IPSE/alpha-1 crystallin fold. Mutational analysis of amino acids in the binding interface showed that residues contributing to IgE binding are important for IgE-dependent activation of basophils. As IPSE/alpha-1 is unable to cross-link IgE, we propose that this molecule, by taking advantage of its unique IgE-binding crystallin fold, activates basophils by a novel, cross-linking-independent mechanism.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Schistosoma Mansoni ; Basophil ; Crystal Structure ; Crystallin ; Interleukin ; Nuclear Magnetic Resonance (nmr)
ISSN (print) / ISBN
0021-9258
e-ISSN
1083-351X
Quellenangaben
Volume: 290,
Issue: 36,
Pages: 22111-22126
Publisher
American Society for Biochemistry and Molecular Biology
Reviewing status
Peer reviewed
Institute(s)
Institute of Structural Biology (STB)