Lipopolysaccharide binding of the mite allergen Der f 2

Authors

  • Saori Ichikawa,

    1. Department of Material and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1, Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan
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  • Toshiro Takai,

    1. Atopy (Allergy) Research Center, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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  • Tomoe Yashiki,

    1. Department of Material and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1, Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan
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  • Seizo Takahashi,

    1. Department of Material and Biological Sciences, Faculty of Science, Japan Women’s University, 2-8-1, Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan
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  • Ko Okumura,

    1. Atopy (Allergy) Research Center, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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  • Hideoki Ogawa,

    1. Atopy (Allergy) Research Center, Juntendo University School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
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  • Daisuke Kohda,

    1. Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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  • Hideki Hatanaka

    Corresponding author
    1. Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
    2. Graduate School of Systems Life Sciences, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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  • Communicated by: Toshio Hakoshima

* hideki@dbcls.jp

Abstract

Lipid-binding properties and/or involvement with host defense are often found in allergen proteins, implying that these intrinsic biological functions likely contribute to the allergenicity of allergens. The group 2 major mite allergens, Der f 2 and Der p 2, show structural homology with MD-2, the lipopolysaccharide (LPS)-binding component of the Toll-like receptor (TLR) 4 signalling complex. Elucidation of the ligand-binding properties of group 2 mite allergens and identification of interaction sites by structural studies are important to explore the relationship between allergenicity and biological function. Here, we report a ligand-fishing approach in which His-tagged Der f 2 was incubated with sonicated stable isotope-labelled Escherichia coli as a potential ligand source, followed by isolation of Der f 2-bound material by a HisTrap column and NMR analysis. We found that Der f 2 binds to LPS with a nanomolar affinity and, using fluorescence and gel filtration assays that LPS binds to Der f 2 in a molar ratio of 1 : 1. We mapped the LPS-binding interface of Der f 2 by NMR perturbation studies, which suggested that LPS binds Der f 2 between the two large β-sheets, similar to its binding to MD-2, the LPS-binding component of the innate immunity receptor TLR4.

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