Assessment of 3D models for allergen research

Authors

  • Trevor D. Power,

    1. Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    2. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
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  • Ovidiu Ivanciuc,

    1. Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    2. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
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  • Catherine H. Schein,

    1. Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    2. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    3. Department of Microbiology and Immunology, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
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  • Werner Braun

    Corresponding author
    1. Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    2. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 310 University Boulevard, Galveston, Texas 77555-0857
    • Sealy Center for Structural Biology and Molecular Biophysics, Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, Texas 77555-0857
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Abstract

Allergenic proteins must crosslink specific IgE molecules, bound to the surface of mast cells and basophils, to stimulate an immune response. A structural understanding of the allergen–IgE interface is needed to predict cross-reactivities between allergens and to design hypoallergenic proteins. However, there are less than 90 experimentally determined structures available for the approximately 1500 sequences of allergens and isoallergens cataloged in the Structural Database of Allergenic Proteins. To provide reliable structural data for the remaining proteins, we previously produced more than 500 3D models using an automated procedure, with strict controls on template choice and model quality evaluation. Here, we assessed how well the fold and residue surface exposure of 10 of these models correlated with recently published experimental 3D structures determined by X-ray crystallography or NMR. We also discuss the impact of intrinsically disordered regions on the structural comparison and epitope prediction. Overall, for seven allergens with sequence identities to the original templates higher than 27%, the backbone root-mean square deviations were less than 2 Å between the models and the subsequently determined experimental structures for the ordered regions. Further, the surface exposure of the known IgE epitopes on the models of three major allergens, from peanut (Ara h 1), latex (Hev b 2), and soy (Gly m 4), was very similar to the experimentally determined structures. For the three remaining allergens with lower sequence identities to the modeling templates, the 3D folds were correctly identified. However, the accuracy of those models is not sufficient for a reliable epitope mapping. © Proteins 2013. © 2012 Wiley Periodicals, Inc.

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