Construction and expression of a dual vector for chemo-enzymatic synthesis of plant indole alkaloids in Escherichia coli

Abstract

A dual vector (pQE-70-STR1-SG) containing coding regions of strictosidine synthase (STR1, EC 4.3.3.2) and strictosidine glucosidase (SG, EC 3.2.1.105) from the Indian medicinal plant Rauvolfia serpentina was constructed. Functional expression of the vector in Escherichia coli cells (M15 strain) was proven by isolation of prepurified enzyme extracts, which show both STR1 and SG activities. Incubation of the enzyme in the presence of tryptamine and secologanin delivered the indole alkaloid cathenamine, demonstrating functional co-expression of both STR1- and SG-cDNAs. Cathenamine reduction by sodium borohydride leading to tetrahydroalstonine revealed the chemo-enzymatic indole alkaloid synthesis.

Keywords:

• Rauvolfia serpentina
• dual vector pQE-70-STR1-SG
• engineered Escherichia coli
• chemo-enzymatic synthesis
• indole alkaloids

Acknowledgements

The authors are grateful to the Deutsche Forschungsgemeinschaft (Bad-Godesberg, Germany), Fonds der Chemischen Industrie (Frankfurt/Main, Germany) and Zhejiang University K.P. Chao Foundation (Hangzhou, China) for support. The original STR1 cDNA-clone was kindly provided by Prof. Kutchan, T.M. (Danforth Center, St Louis, USA).