Determination of the disulfide array of the first inducible antifungal peptide from insects: drosomycin from Drosophila melanogaster.
L Michaut, P Fehlbaum, M Moniatte, A Van Dorsselaer, J M Reichhart, P Bulet
Author Information
L Michaut: Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Réponse Immunitaire et Développement chezles Insectes, Strasbourg, France.
Drosomycin is a 44-residue antifungal peptide with four intramolecular disulfide bridges which have been isolated from immune-challenged Drosophila. To produce adequate amounts of this peptide for 3D-structure analysis, studies on the mode of action and activity spectrum, we expressed a synthetic cDNA in Saccharomyces cerevisiae. For this purpose, we used the mating factor alpha gene and concomitantly overexpressed the KEX2 gene to increase the yield of fully processed drosomycin. Using a combination of Edman degradation and mass spectrometry, we show that drosomycin shares the same array of intramolecular disulfide bridges than plant defensins, in addition to their sequence similarities.
