Mapping of a conformational epitope on the cashew allergen Ana o 2: a discontinuous large subunit epitope dependent upon homologous or heterologous small subunit association.
The 11S globulins are members of the cupin protein superfamily and represent an important class of tree nut allergens for which a number of linear epitopes have been mapped. However, specific conformational epitopes for these allergens have yet to be described. We have recently reported a cashew Ana o 2 conformational epitope defined by murine mAb 2B5 and competitively inhibited by a subset of patient IgE antibodies. The 2B5 epitope appears to reside on the large (acidic) subunit, is dependent upon small (basic) subunit association for expression, and is highly susceptible to denaturation. Here we fine map the epitope using a combination of recombinant chimeric cashew Ana o 2-soybean Gly m 6 chimeras, deletion and point mutations, molecular modeling, and electron microscopy of 2B5-Ana o 2 immune complexes. Key residues appear confined to a 24 amino acid segment near the N-terminus of the large subunit peptide, a portion of which makes direct contact with the small subunit. These data provide an explanation for both the small subunit dependence and the structurally labile nature of the epitope.
Xia
Lixin
L
Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4295, USA.
Willison
LeAnna N
LN
Porter
Lauren
L
Robotham
Jason M
JM
Teuber
Suzanne S
SS
Sathe
Shridhar K
SK
Roux
Kenneth H
KH
D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D052179:Antigens, Plant; D018604:Epitope Mapping / Q000379:methods*; D006801:Humans; D016056:Immunodominant Epitopes / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid
D000485:Allergens; C478880:Ana o 2 allergen, cashew; D000911:Antibodies, Monoclonal; D052179:Antigens, Plant; D016056:Immunodominant Epitopes; D010940:Plant Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins