Fig. 1.

The heterologous mevalonate (MVA) pathway and the native 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway for tricyclic sesquiterpene production. The heterologous MVA pathway from S. cerevisiae was overexpressed in E. coli to convert acetyl-CoA into farnesyl diphosphate (FPP). The endogenous MEP pathway consisting of 9 genes condenses pyruvate and G3P and contributes to FPP supplementation. FPP is converted into three sesquiterpenes by epi-isozizaene synthase (EIZS), pentalenene synthase (PentS) and α-isocomene synthase (MrTPS2). Pathway enzymes are AtoB acetoacetyl-CoA thiolase, HMGS HMG-CoA synthase, HMGR HMG-CoA reductase, MK mevalonate kinase, PMK phosphomevalonate kinase, PMD mevalonate diphosphate decarboxylase, DXS 1-deoxy-d-xylulose 5-phosphate synthase, DXR 1-deoxy-d-xylulose 5-phosphate reductoisomerase, ispD 4-diphosphocytidyl-2C-methyl-d-erythritol synthase, ipk 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase, ispF 2-C-methyl-d-erythritol 2,4-cyclodiphosphate synthase, ispG 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase, ispH 1-hydroxy-2-methyl-butenyl 4-diphosphate reductase, idi IPP isomerase, and ispA FPP synthase. Pathway intermediates are MVA mevalonate, G3P glyceraldehyde 3-phosphate, MEP 2-C-methyl-d-erythritol 4-phosphate, HMBPP 1-hydroxy-2-methyl-2-(E)-butenyl 4-pyrophosphate, IPP isopentenyl diphosphate, DMAPP dimethylallyl diphosphate, and FPP farnesyl diphosphate