De novocurcumin biosynthesis by an engineeredSaccharomyces cerevisiae

Abstract

Curcumin, the major active compound found in Curcuma longa, is extensively studied as a natural cancer-fighting drug. However, curcumin accumulates in low amounts over long periods and its extraction process is costly and inefficient. In addition, its chemical synthesis is complex. Curcumin biosynthesis starts with the phenylpropanoid pathway, whose reactions convert the aromatic amino acids to the curcumin precursor ferulic acid. Subsequently, ferulic acid is converted to curcumin by 4-coumarate-CoA ligase and by type III polyketide synthases (PKSs) using malonyl-CoA as extender substrate. Herein, we developed for the first time a genetically engineered Saccharomyces cerevisiae strain capable of de novo curcumin biosynthesis. CRISPR-Cas9 was used to integrate the biosynthetic pathway. Initially, curcumin production was evaluated from supplemented ferulic acid. The highest curcumin yields were obtained using a bacterial feruloyl-CoA synthetase and type III PKSs from C. longa. Afterwards, the enzymes responsible for the conversion of p-coumaric acid into ferulic acid were expressed in a tyrosine and p-coumaric acid overproducing S. cerevisiae strain. The enzymes included 4-hydroxyphenylacetate 3-hydroxylase subunits from bacteria and caffeic acid O-methyltransferase from Arabidopsis thaliana. After confirming the ferulic acid biosynthesis, the other enzymes responsible for curcumin biosynthesis were expressed in this strain. Other modifications are also being performed to increase yields including increasing of the precursor supply and the deletion of competing pathways.