Expression of Codon-Optimized Plant GlycosyltransferaseUGT72B14inEscherichia coliEnhances Salidroside Production
Salidroside, a plant secondary metabolite inRhodiola, has been demonstrated to have several adaptogenic properties as a medicinal herb. Due to the limitation of plant source, microbial production of salidroside by expression of plant uridine diphosphate glycosyltransferase (UGT) is promising. However, glycoside production usually remains hampered by poor expression of plant UGTs in microorganisms. Herein, we achieved salidroside production by expression ofRhodiolaUGT72B14 inEscherichia coli(E. coli) and codon optimization was accordingly applied.UGT72B14expression was optimized by changing 278 nucleotides and decreasing the G+C content to 51.05% without altering the amino acid sequence. The effect of codon optimization on UGT72B14 catalysis for salidroside production was assessed bothin vitroandin vivo.In vitro, salidroside production by codon-optimized UGT72B14 is enhanced because of a significantly improved protein yield (increased by 4.8-fold) and an equivalently high activity as demonstrated by similar kinetic parameters (KMandVmax), compared to that by wild-type protein.In vivo, both batch and fed-batch cultivation using the codon-optimized gene resulted in a significant increase in salidroside production, which was up to 6.7 mg/L increasing 3.2-fold over the wild-typeUGT72B14.