GATEWAY™ technology and E. coli recombinant system produce a properly folded and functional recombinant allergen of the lipid transfer protein of apple (Mal d 3)

The lipid transfer protein of apple fruit, Mal d 3, has been produced as a soluble recombinant protein in transformed Escherichia coli cells using the GATEWAY™ technology. Circular dichroism spectra showing the protein essentially consists of α-helices indicate that the rMal d 3 is properly folded. The 1H NMR spectra also indicates a correct fold for the recombinant allergen. The reactivity of rMal d 3 towards IgE from apple allergic patients and in vitro degranulation activity measured on transformed rat basophil leukemia cells expressing the human FcεRI α-subunit of rMal d 3 is similar to those of the native allergen purified from apple fruits. The expression of active rMal d 3 in E. coli is readily feasible and offers an interesting alternative to the production of recombinant allergen in the yeast Pichia pastoris. This expression in E. coli open the way to the modification of Mal d 3 by site-directed mutagenesis for immunotherapy purposes.