HETEROLOGOUS PROTEIN SECRETION DIRECTED BY A REPRESSIBLE ACID-PHOSPHATASE SYSTEM OF ASPERGILLUS-NIGER

A new expression-secretion system of Aspergillus niger which directs t he secretion of heterologous proteins is described. The promoter and s ignal peptide-encoding region of the phosphate-repressible aphA gene o f A. niger, when fused to the coding region of the human interferon al pha 2 (hIFN alpha 2)-encoding gene (hIFN alpha 2), drives the expressi on of this gene and the secretion of the hIFN alpha 2 protein. Synthes is of hIFN alpha 2 in either A. niger or A. nidulans transformants car rying these constructs was regulated by inorganic phosphate (P-i) pres ent in the medium, so that derepression of heterologous protein expres sion can be attained by lowering P-i concentration.