Cloning, expression and characterization of a novel four EF-hand Ca2+-binding protein from olive pollen with allergenic activity

A novel allergenic member of the family of Ca2+-binding proteins has been c loned from olive tree pollen. The isolated DNA codes for a protein of 171 a mino acid residues, which displays four EF-hand sequence motifs. The encode d protein was overproduced in Escherichia coli and purified. The protein (1 8 795 Da), which binds Ca2+ and IgE antibodies from patients allergic to ol ive pollen, undergoes Ca2+-dependent conformational changes. It is retained on a phenyl-Sepharose column, which indicates the existence of regulatory EF-hand domains. This fact suggests its involvement in Ca2+-dependent signa l transduction events of the pollen grain. This allergen could be considere d as a member of a new subfamily of EF-hand Ca2+ binding proteins since it displays a low amino acid sequence similarity with the so far known protein s. (C) 2000 Federation of European Biochemical Societies.