Figure 2

Overview of the biosynthetic pathway for β-carotene production. The carotenoid biosynthetic pathway can be reconstructed in S. cerevisiae by overexpression of the native GGPP synthase encoded by BTS1, and co-overexpression of the non-native bifunctional phytoene synthase/lycopene cyclase encoded by crtYB, and phytoene desaturase encoded by crtI of X. dendrorhous. HMG1 encodes the major HMG-CoA reductase activity in S. cerevisiae. ERG9 encodes a farnesyl-diphosphate farnesyl transferase (squalene synthase) that acts in the sterol biosynthesis pathway. IPP isopentenyl diphosphate, DMAP dimethylallyl diphosphate, GPP geranyl diphosphate, FPP farnesyl diphosphate, GGPP geranylgeranyl diphosphate.