Fig. 5.

Engineered yeast platform for the enhanced production of pentacyclic triterpenes. The MVA pathway was pushed by the overexpression of ERG13 and tHMGR, and pulled by the knockout of ROX1 to enhance the productivity of MVA pathway and late sterol biosynthesis. To redirect metabolic flux from late sterol biosynthesis into the synthesis of pentacyclic triterpenes by the T. koksaghyz lupeol synthase (TkLUP), the CTR3 promoter (P_CTR3) was used to inhibit the expression of ERG7 following the addition of copper (Cu²⁺). An additional effect on 2,3-oxidosqualene accumulation was achieved by the missing repression of ERG9 and ERG1 due to the lower sterol content (lanosterol and ergosterol). Dashed arrows represent multiple enzymatic reactions