De novo biosynthesis of C-arabinosylated flavones by utilization of indica rice C-glycosyltransferases

Abstract

Abstract Flavone C -arabinosides/xylosides are plant-originated glycoconjugates with various bioactivities. However, the potential utility of these molecules is hindered by their low abundance in nature. Engineering biosynthesis pathway in heterologous bacterial chassis provides a sustainable source of these C -glycosides. We previously reported bifunctional C -glucosyl/ C -arabinosyltransferases in Oryza sativa japonica and O. sativa indica, which influence the C -glycoside spectrum in different rice varieties. In this study, we proved the C -arabinosyl-transferring activity of rice C -glycosyltransferases (CGTs) on the mono- C -glucoside substrate nothofagin, followed by taking advantage of specific CGTs and introducing heterologous UDP-pentose supply, to realize the production of eight different C -arabinosides/xylosides in recombinant E. coli . Fed-batch fermentation and precursor supplement maximized the titer of rice-originated C -arabinosides to 20–110 mg/L in an E. coli chassis. The optimized final titer of schaftoside and apigenin di- C -arabinoside reached 19.87 and 113.16 mg/L, respectively. We demonstrate here the success of de novo bio-production of C -arabinosylated and C -xylosylated flavones by heterologous pathway reconstitution. These results lay a foundation for further optimal manufacture of complex flavonoid compounds in microbial cell factories.