NMR structure and IgE epitopes of Blo t 21, a major dust mite allergen from Blomia tropicalis.
Blo t 21 is a paralogue of the group 5 allergen, Blo t 5, a major allergen from the dust mite Blomia tropicalis. Blo t 21 has moderate sequence identity (40.7%) to Blo t 5 and low to moderate cross-reactivity to Blo t 5. In B. tropicalis, the most prevalent and allergenic allergens are in the order of Blo t 21, Blo t 5, and Blo t 7. Here, we determined the NMR solution structure of Blo t 21, which represents the first structure of the group 21 dust mite allergen. The structure of Blo t 21 closely resembles the structures of Blo t 5 and Der p 5, comprising three anti-parallel α-helices arranged in a helical bundle. Using site-directed mutagenesis and specific IgE binding ELISA, Blo t 21 was found to contain both conserved and unique charged IgE epitope residues at the L2 loop region and on helix α3. Cross-inhibition assays confirmed that Blo t 21 has a low to moderate cross-reactivity with Blo t 5 and Der p 5 and represents a novel group of major allergen in B. tropicalis. In addition to group 5 allergens, Blo t 21 has also a low to moderate cross-reactivity with group 21 allergens from Dermatophagoides mites, confirming that B. tropicalis is a major and distinct source of dust mite allergens.
Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore.
Kang Wei
KW
Tan
Tan Ching
TC
Ong
Yun Feng
YF
Gao
Yuen Sung
YS
Tiong
Kang Ning
KN
Wong
Fook Tim
FT
Chew
Yu Keung
YK
Mok
D000485:Allergens / Q000737:chemistry* / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000737:chemistry / Q000276:immunology; D060829:Arthropod Proteins / Q000737:chemistry / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology; D007073:Immunoglobulin E / Q000737:chemistry* / Q000276:immunology; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D039981:Pyroglyphidae / Q000737:chemistry* / Q000276:immunology; D040681:Structural Homology, Protein
D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451239:Dermatophagoides pteronyssinus antigen p 5; D000939:Epitopes; C094701:allergen Blo t 5; D007073:Immunoglobulin E