Download MendeleyA Crystallin Fold in the Interleukin-4-Inducing Principle of Schistosoma Mansoni Eggs (Ipse/Alpha-1) Mediates Ige Binding for Antigen-Independent Basophil Activation
Meyer, N.H., Mayerhofer, H., Tripsianes, K., Barths, D., Blindow, S., Bade, S., Madl, T., Frey, A., Haas, H., Mueller-Dieckmann, J., Sattler, M., Scharmm, G.(2015) J Biol Chem 290: 22111
- PubMed: 26163514
- DOI: https://doi.org/10.1074/jbc.M115.675066
- Primary Citation of Related Structures:
4AKA - PubMed Abstract:
The IL-4-inducing principle from Schistosoma mansoni eggs (IPSE/α-1), the major secretory product of eggs from the parasitic worm S. mansoni, efficiently triggers basophils to release the immunomodulatory key cytokine interleukin-4. Activation by IPSE/α-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/α-1 mutant, revealed that IPSE/α-1 is a new member of the βγ-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/α-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/α-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.
Organizational Affiliation:
From the Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, the Munich Center for Integrated Protein Science and Biomolecular NMR, Department of Chemie, Technische Universität München, 85747 Garching.
