SmCYP71D373 of Salvia miltiorrhiza catalyzes the methyl oxidation reaction of tanshinone IIA-19 position

Salvia miltiorrhiza is one of the most commonly used Chinese medicinal herbs. Tanshinone I and tanshinone IIB with anti-inflammatory, anti-bacterial, anti-oxidative, anti-neoplastic, neuron protective, and heart protective properties are valuable active components in it. However, the biosynthetic pathway of tanshinone IIB and tanshinone I has not been completely elucidated. Here, we identified a tanshinone IIA 19-hydroxylase from S. miltiorrhiza . In vitro and in vivo analyses showed that SmCYP71D373 could hydroxylate tanshinone IIA at C-19 position to produce tanshinone IIB. Reaction conditions optimization demonstrated that the catalytic efficiency of SmCYP71D373 was the highest using the substrate-feeding method under the following conditions, fed the tanshinone IIA into the Saccharomyces cerevisiae expressing codon-optimized SmCYP71D373 at 28 degree celsius for 24 hours. And the yield of tanshinone IIB was up to 6.38%. Furthermore, N121 and S210 of SmCYP71D373 were verified as the key amino acid residues responsible for its catalytic activity for tanshinone IIA by molecular docking and sitedirected mutagenesis. The results not only lay a foundation for the elucidation of tanshinone I synthesis pathway, but also provide the theoretical support to improve the catalytic efficiency of SmCYP71D373 for tanshinone IIB production.