Molecular cloning and expression of Cro s 1: an occupational allergen from saffron pollen (crocus sativus)

Background: the cultivation of saffron is expanding through the southeast of iran, and allergy tosaffron pollen occurs in workers involved in processing this plant. we aimed to clone, sequence andexpress a major allergen involved in saffron pollen allergy, and to compare the recombinant with thenatural allergen.methods: the n-terminal amino acid sequence of cro s 1, an allergen from saffron pollen, wasdetermined after immunoblotting. the cdna encoding for this allergen was cloned by pcr utilizing aprimer based on the n-terminal amino acid sequence. recombinant cro s 1 (rcro s 1) was expressed asa soluble protein in pichia pastoris and purified to homogeneity by gel filtration. inhibition of igebinding to rcro s 1 by pollen extract was analyzed by elisa.results: the allergen cro s 1 was identified from saffron pollen extracts and cloned by pcr. cro s 1cdna defined an acidic polypeptide with homology to pollen proteins from chenopodium album andligastrum vulgaris. the rcro s 1 was expressed in p. pastoris at 28 mg/l. saffron pollen extractinhibited the binding of patient serum ige to rcro s 1.conclusion: we identified and cloned the first crocus sativus pollen allergen. rcro s 1 cdna shows avery high homology with che a 1, the major allergen of lamb's-quarter, chenopodium album,caryophyllales, pollen (97%). cro s 1 is a useful tool for specific diagnosis and structural studies ofoccupational allergy to saffron.