Ole e 9, a major olive pollen allergen is a 1,3-β-glucanase -: Isolation, characterization, amino acid sequence, and tissue specificity

Olive pollen allergy is a clinical disorder affecting the human population of Mediterranean areas. A novel major allergen, Ole e 9, has been isolated from olive pollen by gel permeation, hydrophobic affinity, and reverse-phase high performance liquid chromatographies. It is involved in the allergic responses of 65% of patients suffering olive pollinosis. Ole e 9 (molecular mass of 46.4 kDa) displays 1,3-beta -endoglucanase activity (38.9 +/- 5.6 mg of glucose released/min x mu mol of protein at pH 4.5-6.0 using laminarin as substrate). It is the first 1,3-beta -glucanase, a member of the "pathogenesis-related" protein family, detected in pollen tissue. Seven tryptic peptides of the allergen were sequenced by Edman degradation and used for designing primers to clone the cDNA codifying the protein. Specific cDNA for Ole e 9 was synthesized from total RNA and amplified using the polymerase chain reaction. The allergen sequence showed an open reading frame of 460 amino acids comprising a putative signal peptide of 26 residues. It shows 39, 33, and 32% sequence identity including the catalytic residues when compared with 1,3-beta -glucanases from wheat, willow, and Arabidopsis thaliana, respectively. Northern blot analysis showed that Ole e 9 transcript is specifically expressed in the pollen tissue, and highly conserved counterparts were only detected in taxonomically related pollens.