Nucleotide sequence of cDNA encoding the group II allergen of cocksfoot/orchard grass (Dactylis glomerata), Dac g II.

Abstract

Cocksfoot/orchard grass (Dactylis glomerata) anther cDNA clones encoding the group II allergen Dac g II were previously isolated on the basis of immunoreactivity of human, rabbit, and murine antibodies with a 24-kDa protein expressed as a fusion protein with beta-galactosidase. Nucleotide sequencing reveals an open reading frame predicting expression of a 98-amino-acid (11-kDa) polypeptide exhibiting > 90% homology with the group II allergen of Lolium perenne, Lol p II. In vitro translation of different sized clone fragments generated by polymerase chain amplification confirms eukaryotic expression of a 10-12-kDa polypeptide by SDS-PAGE and the position of a translational stop apparently unrecognized during expression of lambda gt11 in E. coli. The unusual characteristics of the prokaryote-expressed fusion proteins may be exerting conformational alterations in Dac g II, as reflected by previous demonstrations of differences in human IgE immunoreactivity. Northern blot analysis using PCR-generated partial and full-length probes suggests that group II allergens may be encoded by a different family or families of temporally expressed genes from those encoding group I major allergens, although a group I gene may have been the progenitor.