Expression of functional Raphanus sativus antifungal protein in yeast

Rs-AFP2 is a 51 amino acid cysteine-rich peptide isolated from radish (Raphanus sativus) seeds that exhibits potent inhibitory activity against filamentous fungi. A cDNA clone encoding the Rs-AFP2 preprotein was modified by recombinant DNA methods to allow expression in the yeast Saccharomyces cerevisiae. This peptide was expressed in yeast as a fusion protein carrying at its N-terminus the prepro-sequences derived from the precursor of the yeast pheromone mating factor alpha 1. These sequences allow secretion of the biologically active peptide in a correctly processed form. Deletion of the mating factor alpha 1 pro-peptide drastically reduced the expression level of the peptide.