Engineering budding yeast for the de novo synthesis of valuable flavanone derivatives†

Abstract

Flavonoids, such as homoeriodictyol derivatives, hold significant value in nutraceuticals, foods, and pharmaceuticals. Microbial synthesis of these products has emerged as a powerful approach due to its sustainability and environmental friendliness. However, constructing microbial cell factories of homoeriodictyol derivatives is often challenged by the lack of a biosynthesis pathway and the poor performance of endogenous metabolic networks. Here, an efficient Saccharomyces cerevisiae cell factory was designed and metabolically engineered for the de novo biosynthesis of homoeriodictyol 7-O-glucoside. Relieving the feedback inhibition and overexpressing the key enzymes successfully achieved the biosynthesis of homoeriodictyol with a titer of 174.0 mg L⁻¹. Enzyme screening strategies explored missing glycosyltransferases and unveiled the homoeriodictyol 7-O-glucoside synthesis pathway for the first time. Blocking the glycoside hydrolysis pathway improved the titer of homoeriodictyol 7-O-glucoside by a substantial 7.2-fold. Metabolically regulating NADPH regeneration reduced the intermediate accumulation by 91.3%, while strengthening uridine diphosphate-glucose and substrate supply further boosted the homoeriodictyol 7-O-glucoside production. Altogether, these advancements led to a record homoeriodictyol 7-O-glucoside titer of 600.2 mg L⁻¹ and a yield of 12.2 mg g⁻¹ glucose. Overall, the versatile S. cerevisiae cell factory shows the potential to synthesize homoeriodictyol 7-O-glucoside, contributing to the green and sustainable production of natural products.