title: Lipopolysaccharide binding of the mite allergen Der f 2.
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 beta-sheets, similar to its binding to MD-2, the LPS-binding component of the innate immunity receptor TLR4.
authors.affiliation: Department of Material and Biological Sciences, Faculty of Science, Japan Women's University, Bunkyo-ku, Tokyo 112-8681, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Ichikawa
authors.forename: Toshiro
authors.initials: T
authors.lastname: Takai
authors.forename: Tomoe
authors.initials: T
authors.lastname: Yashiki
authors.forename: Seizo
authors.initials: S
authors.lastname: Takahashi
authors.forename: Ko
authors.initials: K
authors.lastname: Okumura
authors.forename: Hideoki
authors.initials: H
authors.lastname: Ogawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kohda
authors.forename: Hideki
authors.initials: H
authors.lastname: Hatanaka
mesh_terms: D000485:Allergens / Q000378:metabolism*; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000737:chemistry / Q000378:metabolism*; D060829:Arthropod Proteins; D001665:Binding Sites; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000378:metabolism; D008024:Ligands; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451160:Dermatophagoides farinae antigen f 2; D008024:Ligands; D008070:Lipopolysaccharides