Selection of Optimum Expression System for Production of Kringle Fragment of Human Apolipoprotein(a) in Saccharomyces cerevisiae

Recombinant Saccharomyces cerevisiae expression systems were developed to pro­duce a novel human anti-angiogenic protein called LK8, an 86 amino-acid kringle fragment pro­tein with three disulfide linkages. Galactose-inducible LK8 expression plasmid was constructed, and LK8 production levels by four S. cerevisiae strains were compared in order to select an op­timal host strain. S. cerevisiae 2805 was the most efficient among the strains tested. Elevating the LK8 gene copy number through multiple integration using 8-sequences as target sites re­sulted in more than a two-fold increase in the LK8 production level compared with the plasmid­based expression system. The maximum LK8 protein concentration of 25 mg/L was obtained from batch cultivation of the yeast transformant that harbors 16 copies of the LK8 gene. In con­clusion, the strain integrated with the multiple LK8 gene secreted the protein with relatively high yield, although, the increased LK8 gene dosage over 11 copies did not lead to further en­hancement in batch cultivations.