Secretion of active human lysozyme by Acremonium chrysogenum using a Fusarium alkaline protease promoter system

We constructed expression vectors for Acremonium chrysogenum using a Fusarium alkaline protease promoter region and tested their potential as secretion systems for foreign proteins using the human (h)-lysozyme gene as an indicator. The gene encoding h-lysozyme was linked to the coding region of (1) the carboxy terminal of the alkaline protease pre peptide, (2) the carboxy terminal of the prepro peptide, (3) three amino acids of the mature protein preceded by the prepro peptide and (4) the carboxy terminal of chicken lysozyme signal peptide, inserted into the genomic DNAs of A. chrysogenum and expressed under the control of the alkaline protease promoter. The transformants of A. chrysogenum with each of these plasmids secreted enzymatically active h-lysozyme. A maximum yield in excess of 40 mg l-1 was obtained when h-lysozyme was linked to the carboxy terminal of alkaline protease prepro peptide. The majority of the amino terminal sequence of the purified h-lysozyme from the culture supernatant was identical with that of authentic h-lysozyme, but it showed some heterogeneity.