Par j 1 and Par j 2, the major allergens from Parietaria judaica pollen, have similar immunoglobulin E epitopes.
BACKGROUND
Parietaria judaica is the main cause of allergy in Mediterranean countries. The major allergens from P. judaica pollen, Par j 1 and Par j 2, have amino acid sequence identity of 45% and contain eight cysteine residues involved in disulphide bonds that compact the structure.


OBJECTIVE
The aim of the study was to identify IgE-binding epitopes on Par j 1 and Par j 2, the major allergens from P. judaica pollen and correlate them with the three-dimensional structure of the proteins.


METHODS
Overlapping peptides representing the complete length of Par j 1 and Par j 2 were synthesized on a cellulose-derivatized membrane. Sera from 17 P. judaica-allergenic patients were used to identify IgE-binding epitopes. Homology modelling of the three dimensional structure of both allergens was generated using the Swiss-Model software on the basis of previously reported crystal structures.


RESULTS
Five and eight IgE-binding epitopes were identified on Par j 1 and Par j 2 allergens, respectively. Both proteins belonged to the non-specific lipid transfer proteins (ns-LTP) family and therefore a three-dimensional model of both allergens was constructed on the basis of the maize ns-LTP crystal structure. Par j 1 and Par j 2 allergens have three similar allergenic epitopes with high homology and identical conformation.


CONCLUSIONS
Three similar IgE-epitopes of major allergens from P. judaica have been described. They could be good candidates for designing of IgE haptens as therapeutic agents with reduced anaphylactic side-effects or for developing hypoallergenic variants of these major allergens.
Asturias
J A
JA
Bial-Arístegui, Research and Development Department, Bilbao, Spain. la.lp@bial.es
Gómez-Bayón
N
N
Eseverri
J L
JL
Martínez
A
A
D000485:Allergens / Q000235:genetics / Q000276:immunology*; D052179:Antigens, Plant; D001665:Binding Sites; D000939:Epitopes / Q000032:analysis*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007073:Immunoglobulin E / Q000276:immunology*; D008969:Molecular Sequence Data; D032403:Parietaria; D010449:Peptide Mapping; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology*; D011058:Pollen; D016415:Sequence Alignment; D017385:Sequence Homology
D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; C103299:Par j 2.0101; C083860:Par j I protein, Parietaria judaica; D010940:Plant Proteins; D007073:Immunoglobulin E