Production of minor ginsenosides using identified novel ginseng UDP-glycosyltransferases in Saccharomyces cerevisiae

Ginseng is a medicinal herb that requires cultivation under shade conditions, typically for 6 yr, before harvesting. The principal components of ginseng are ginsenosides, glycosylated tetracyclic terpenes. Ginsenosides are classified into two groups, protopanaxadiol (PPD) and protopanaxatriol (PPT), based on their hydroxylation patterns, and further diverge to diverse ginsenosides through differential glycosylation. Three early enzymes, Dammarenediol-II synthase (DS) and two P450 enzymes, protopanaxadiol synthase (PPDS) and protopanaxatriol synthase (PPTS), have been reported, but glycosyltransferases that are necessary to synthesize specific ginsenosides have not yet been fully identified. To discover glycosyltransferases responsible for ginsenoside biosynthesis, we sequenced and assembled the ginseng transcriptome de novo and characterized three UDP-glycosyltransferases (PgUGTs): PgUGT74A1, PgUGT94B1 and PgUGT31. Synthetic pathways of various minor ginsenosides were constructed in S. cerevisiae by introducing DS, PPDS and UGTs for development of minor ginsenoside production strains. In the results, we produced various minor ginsenosides through fed-batch fermentation using developed yeast strains