CDNA CLONING AND EXPRESSION OF TIMOTHY GRASS (PHLEUM-PRATENSE) POLLENPROFILIN IN ESCHERICHIA-COLI - COMPARISON WITH BIRCH POLLEN PROFILIN

Profilin, an actin-binding protein,was previously described as a ubiqu itous allergen which is responsible for crossreactivities in about 20% of pollen and food allergic patients. A complete cDNA clone coding fo r timothy grass (Phleum pratense) pollen profilin was isolated using a llergic patients IgE. The deduced amino acid sequence of timothy grass profilin shares a sequence identity of 79% with birch profilin and ot her plant profilins and a lower average sequence identity of 35% with other eukaryotic profilins. The high degree of homology among differen t plant profilins at the DNA and protein level explains the extensive cross-reactivities observed in profilin allergic patients. Recombinant timothy grass pollen profilin was expressed in Escherichia coli as a B-galactosidase fusion protein and shown to bind IgE from profilin all ergic patients similar to recombinant birch profilin. Slight differenc es regarding the IgE-binding capacity of birch and timothy grass profi lin indicate that not all IgE-epitopes of the two profilins are conser ved. It is speculated that profilin allergic patients were initially s ensitized against a certain profilin and then cross-react with the hom ologous proteins. (C) 1994 Academic Press, Inc.