Abstract
Isoflavones are predominantly found in legumes and play roles in plant defense and prevention of estrogen-related diseases. Genistein is an important isoflavone backbone with various biological activities. In this paper, we describe how a cell factory that can de novo synthesize genistein was constructed in Saccharomyces cerevisiae. Different combinations of isoflavone synthase, cytochrome P450 reductase, and 2-hydroxyisoflavone dehydratase were tested, followed by pathway multicopy integration, to stably de novo synthesize genistein. The catalytic activity of isoflavone synthase was enhanced by heme supply and an increased intracellular NADPH/NADP(+) ratio. Redistribution of the malonyl-CoA flow and balance of metabolic fluxes were achieved by adjusting the fatty acid synthesis pathway, yielding 23.33 mg/L genistein. Finally, isoflavone glycosyltransferases were introduced into S. cerevisiae, and the optimized strain produced 15.80 mg/L of genistin or 10.03 mg/L of genistein-8-C-glucoside. This is the first de novo synthesis of genistein-8-C-glucoside in S. cerevisiae, which is advantageous for the green industrial production of isoflavone compounds.