De Novo Biosynthesis of Sakuranetin in <i>Yarrowia lipolytica</i> Through Systemic Metabolic Engineering

The methylated flavonoid sakuranetin, primarily found in barks and leaves, exhibits potent antifungal, antiviral, and anti-inflammatory effects. Microbial metabolic engineering strategies for its synthesis have gained interest because the extraction of this compound from plants is inefficient. Moreover, whereas the sakuranetin yields from microorganisms remain low, the yeast Yarrowia lipolytica has received recent attention as a promising host cell for compound biosynthesis. In this study, the de novo synthesis of sakuranetin from glucose was achieved in Y. lipolytica through metabolic engineering. First, a synthetic titer of 154.80 mg/L was obtained by introducing methyltransferase into the naringenin-synthesizing strain. By screening promoters to enhance the expression of methyltransferase, augmenting the supply of the methyl donor SAM, increasing shikimic acid pathway flux, and adjusting the copy number of gene involved in sakuranetin synthesis, the breakthrough sakuranetin titer reached 345.42 mg/L, which was 1.2 times higher than that when using the primary strain. Finally, the strategy to optimize the glucose concentration resulted in a sakuranetin titer that increased to 686.81 mg/L. This paper reports the highest yield of de novo synthesis of sakuranetin by Y. lipolytica, as a potential synthetic chassis for the biosynthesis of naringenin and other flavonoid compounds.