Inducible amplification of gene copy number and heterologous protein production in the yeast Kluyveromyces lactis

Heterologous protein production can be doubled by increasing the copy numbe r of the corresponding heterologous gene. We constructed a host-vector syst em in the yeast Kluyveromyces lactis that was able to induce copy number am plification of pKD1 plasmid-based vectors upon expression of an integrated copy of the plasmid recombinase gene. We increased the production and secre tion of two heterologous proteins, glucoamylase from the yeast Arxula adeni nivorans and mammalian interleukin-1 beta, following gene dosage amplificat ion when the heterologous genes were carried by pKD1-based vectors. The cho ice of the promoters for expression of the integrated recombinase gene and of the episomal heterologous genes are critical for the mitotic stability o f the host-vector system.