HEN EGG-WHITE LYSOZYME EXPRESSED IN, AND SECRETED FROM, ASPERGILLUS-NIGER IS CORRECTLY PROCESSED AND FOLDED

We transformed Aspergillus niger with the full length cDNA gene encoding hen egg-white lysozyme (HEWL) and its secretion signal sequence. Lysozyme levels up to 12 mg/1 were secreted when expression was controlled by the A. awamori glucoam-ylase (GAM) promoter and 1 mg/1 when controlled by the A. nidulans glyceralde-hyde-3-phosphate dehydrogenase (GPD) promoter. N-terminal sequence analysis of the recombinant protein indicated that the signal peptide was correctly processed by the A. niger secretory apparatus. The specific catalytic activity of the recombinant protein was identical to that of authentic hen lysozyme. The recombinant HEWL was examined by 2D XH-NMR spectrosco-py and shown to have a spectrum identical to that of authentic HEWL indicating that the protein was correctly folded. © 1990 Nature Publishing Group.