Fig. 1

De novo synthesis and elongation of fatty acids (FAs), fatty alcohols (FOHs) and wax esters (WEs) in S. cerevisiae. The first step shown in the reaction scheme is the carboxylation of acetyl-CoA to malonyl-CoA catalyzed by acetyl-CoA carboxylase (Acc1p) in the cytosol. In our study, a mutant version of Acc1p, containing two amino acid substitutions (S659A; S1157A), was used (Acc1p**). The next step in the synthesis of FAs in the cytosol is a series of reactions catalyzed by the fatty acid synthases 1 (Fas1p) and 2 (Fas2p) which leads to fatty acyl CoAs (FACoAs) with a chain length of C12-C18. The acyl-CoA binding protein (Acb1p) transports newly synthesized acyl-CoA esters from Fas1p–Fas2p to acyl-CoA-consuming processes. The elongation and desaturation of C12-C18 FACoAs is performed at the endoplasmic reticulum (ER). The desaturation of FAs in S. cerevisiae is catalyzed by Ole1p, a fatty acid desaturase (FAD) acting on C12-C19 FAs. This scheme also shows a heterologous FAD (green) which is able to insert a double bond into very long-chain FAs (C20-C26). The elongation of FAs in S. cerevisiae is catalyzed by a β-ketoacyl-CoA synthase (KCS), a β-ketoacyl-CoA reductase (KCR), a β-hydroxyacyl-CoA dehydratase (HCD) and an enoyl-CoA reductase (ECR) and leads to the production of C16-C26 FACoAs in yeast. FACoAs can be reduced by a heterologous fatty acyl-CoA reductase (FAR) to a fatty aldehyde and further to a FOH. A wax synthase (WS) catalyzes the esterification of a FOH with another FACoA molecule to form a WE. All yeast intrinsic enzymes are indicated in grey, whereas heterologous ones are indicated in green