An experimental and modeling-based approach to locate IgE epitopes of plant profilin allergens.
BACKGROUND
Plant profilins are actin-binding proteins that form a well-known panallergen family responsible for cross-sensitization between plant foods and pollens. Melon profilin, Cuc m 2, is the major allergen of this fruit.


OBJECTIVE
We sought to map IgE epitopes on the 3-dimensional structure of Cuc m 2.


METHODS
IgE binding to synthetic peptides spanning the full Cuc m 2 amino acid sequence was assayed by using a serum pool and individual sera from 10 patients with melon allergy with significant specific IgE levels to this allergen. Three-dimensional modeling and potential epitope location were based on analysis of both solvent exposure and electrostatic properties of the Cuc m 2 surface.


RESULTS
Residues included in synthetic peptides that exerted the strongest IgE-binding capacity defined 2 major epitopes (E1, consisting of residues 66-75 and 81-93, and E2, consisting of residues 95-99 and 122-131) that partially overlapped with the actin-binding site of Cuc m 2. Two additional epitopes (E3, including residues 2-10, and E4, including residues 35-45) that should show weaker putative antigen-antibody associations and shared most residues with synthetic peptides with low IgE-binding capacity were predicted on theoretical grounds.


CONCLUSIONS
Strong and weak IgE epitopes have been uncovered in melon profilin, Cuc m 2.


CONCLUSIONS
The different types of IgE epitopes located in the 3-dimensional structure of melon profilin can constitute the molecular basis to explain the sensitization and cross-reactivity exhibited by this panallergen family.
López-Torrejón
Gema
G
Unidad de Bioquímica, Departamento de Biotecnología, E. T. S. Ingenieros Agrónomos, Madrid, Spain.
Díaz-Perales
Araceli
A
Rodríguez
Julia
J
Sánchez-Monge
Rosa
R
Crespo
Jesus F
JF
Salcedo
Gabriel
G
Pacios
Luis F
LF
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000737:chemistry / Q000276:immunology*; D001666:Binding Sites, Antibody; D003429:Cross Reactions / Q000276:immunology; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood* / Q000737:chemistry; D018448:Models, Immunological; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology*; D051304:Profilins / Q000737:chemistry / Q000276:immunology*; D017433:Protein Structure, Secondary; D055672:Static Electricity
D000199:Actins; D000485:Allergens; D052179:Antigens, Plant; C507132:Cuc m 2 allergen, Cucumis melo; D000939:Epitopes; D010940:Plant Proteins; D051304:Profilins; D007073:Immunoglobulin E