cDNA cloning and expression of timothy grass (Phleum pratense) pollen profilin in Escherichia coli: comparison with birch pollen profilin.
Profilin, an actin-binding protein, was previously described as a ubiquitous allergen which is responsible for cross-reactivities in about 20% of pollen and food allergic patients. A complete cDNA clone coding for timothy grass (Phelum pratense) pollen profilin was isolated using allergic patients IgE. The deduced amino acid sequence of timothy grass profilin shares a sequence identity of 79% with birch profilin and other plant profilins and a lower average sequence identity of 35% with other eukaryotic profilins. The high degree of homology among different 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 beta-galactosidase fusion protein and shown to bind IgE from profilin allergic patients similar to recombinant birch profilin. Slight differences regarding the IgE-binding capacity of birch and timothy grass profilin indicate that not all IgE-epitopes of the two profilins are conserved. It is speculated that profilin allergic patients were initially sensitized against a certain profilin and then cross-react with the homologous proteins.
Valenta
R
R
Institute of General and Experimental Pathology, University of Vienna, Austria.
Ball
T
T
Vrtala
S
S
Duchêne
M
M
Kraft
D
D
Scheiner
O
O
D000485:Allergens / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003285:Contractile Proteins; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D006109:Poaceae; D011058:Pollen; D051304:Profilins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012995:Solubility; D014197:Trees
D000485:Allergens; D003285:Contractile Proteins; D018076:DNA, Complementary; D008840:Microfilament Proteins; D051304:Profilins; D007073:Immunoglobulin E