A novel heterologous gene expression system in Saccharomyces cerevisiae using the isocitrate lyase gene promoter from Candida tropicalis

We have found that the upstream region of the isocitrate lyase gene (UPR-ICL) from the n-alkane-utilizing yeast Candida tropicalis was functional in Saccharomyces cerevisiae as a novel promoter with nonfermentable carbon sources, such as oleic acid, acetate, ethanol, and glycerol/lactate. The expression of two foreign genes coding for beta-galactosidase from Escherichia coli (LacZ) and glutamate decarboxylase from rat brain was carried out under the control of UPR-ICL. Expression of LacZ was repressed by glucose and enhanced over 300-fold by acetate. When an expression vector pWI3 containing multicloning sites between UPR-ICL and the transcriptional terminator of the isocitrate lyase gene (TERM-ICL) was used, the smaller isoform of glutamate decarboxylase (GAD(65)) was highly produced in a soluble and active form. These results demonstrate that the novel expression system using UPR-ICL and TERM-ICL from C. tropicalis is useful for the production of heterologous proteins in S. cerevisiae.