The Presence of Actinidin (Cysteine Protease) and Recombinant Plasmids Carrying the Actinidin Gene Influence the Growth of Saccharomyces Cerevisiae

Actinidin is a protease found abundantly in the fruit of Actinidia chinensis or Kiwi fruit. The overproduction of this protein in microorganisms, especially using the yeast Saccharomyces cerevisiae, would be economically valuable as it would simplify the extraction and purification of the protein. It was observed, however, that the yeast growth rate was reduced by the presence of externally supplied actinidin in the growth medium. It was also observed that actinidin present in the yeast growth medium was partially degraded. Several actinidin-encoding gene variants have been cloned in a yeast expression and secretion vector. It was observed that different actinidin gene constructions influenced the growth rate of S. cerevisiae in complete media. Recombinant plasmids carrying only the mature actinidin-encoding DNA sequences reduced yeast transformability significantly and had the least stability. The results thus suggest that the presence of a recombinant plasmid carrying a gene of a potentially toxic protein may result in a deleterious effect on the host cell.