Establishing biosynthetic pathway for the production of p-hydroxyacetophenone and its glucoside in Escherichia coli

p-Hydroxyacetophenone (p-HAP) and its glucoside picein are plant-derived natural products that have been extensively used in chemical, pharmaceutical and cosmetic industries owing to their antioxidant, antibacterial and antiseptic activities. However, the natural biosynthetic pathways for p-HAP and picein have yet been resolved so far, limiting their biosynthesis in microorganisms. In this study, we design and construct a biosyn-thetic pathway for de novo production of p-HAP and picein from glucose in E. coli. First, screening and char-acterizing pathway enzymes enable us to successfully establish functional biosynthetic pathway for p-HAP production. Then, the rate-limiting step in the pathway caused by a reversible alcohol dehydrogenase is completely eliminated by modulating intracellular redox cofactors. Subsequent host strain engineering via sys-tematic increase of precursor supplies enables production enhancement of p-HAP with a titer of 1445.3 mg/L under fed-batch conditions. Finally, a novel p-HAP glucosyltransferase capable of generating picein from p-HAP is identified and characterized from a series of glycosyltransferases. On this basis, de novo biosynthesis of picein from glucose is achieved with a titer of 210.7 mg/L under fed-batch conditions. This work not only demonstrates a microbial platform for p-HAP and picein synthesis, but also represents a generalizable pathway design strategy to produce value-added compounds.

Automated summary

In this study, a biosynthetic pathway was designed and constructed in E. coli for the de novo production of p-Hydroxyacetophenone (p-HAP) and its glucoside picein from glucose. The rate-limiting step in the pathway was eliminated by modulating intracellular redox cofactors, resulting in a high production of p-HAP. A novel p-HAP glucosyltransferase capable of generating picein was also identified and characterized. The successful biosynthesis of picein from glucose demonstrates the potential of this pathway design strategy for producing valuable compounds.