Enhancement of tropane alkaloids biosynthesis in Atropa belladonna hariy root by overexpression of HnCYP82M3 and DsTRI genes / 药学学报

ABSTRACT

Tropane alkaloids (TAs) are a class of anticholinergic drugs widely used in clinical practice and mainly extracted from plant, among which Atopa belladonna is the main commercial drug source. It is of great industrial value to obtain TAs in large quantities by plant metabolic engineering. In TAs pathway, cytochrome oxidase CYP82M3 catalyze the synthesis of tropinone and then tropinone reductase I (TRI) compete with TRII for tropinone to form tropine leading to the TAs synthesis (drainage). In this study, based on the "increasing flow and drainage" metabolic engineering strategy, two genes, namely HnCYP82M3 and DsTRI from Hyoscyamus niger and Datura stramonium, respectively, were overexpressed in the hair roots of A. belladonna, with a view to promote the TAs accumulation. The HnCYP82M3 gene was cloned from the root of H. niger, and it encoded amino acid with 91.7% sequence identity with AbCYP82M3 from A. belladonna. Overexpression of HnCYP82M3 alone did not affect the content of TAs in hair roots of A. belladonna, indicating that CYP82M3 was not a key enzyme in TAs biosynthesis. Simultaneous overexpression of HnCYP82M3 and DsTRI greatly promoted the accumulation of the three TAs, and the contents of hyoscyamine, anisodamine and scopolamine were 4.97 times, 2.83 times and 2.19 times that of the control, respectively, and the increase amplitude was greater than that of single overexpression of DsTRI. This study showed that the "increasing flow and drainage" strategy of enzyme genes co-expression at branch points was a promising metabolic engineering method to effectively improve the biosynthesis of TAs in A. belladonna, and laid a theoretical and technical foundation for the large-scale industrial acquisition of TAs.