Curcumin synthase

Abstract: Ginger (Zingiber officinale Rosc.) is a popular flavoring that widely used in Asian, and the volatile oil in ginger rhizomes adds a special fragrance and taste to foods. The bioactive compounds in ginger, such as gingerols, diarylheptanoids, and flavonoids, are of significant value to human health because of their anticancer, anti-oxidant, and anti-inflammatory properties. However, as a non-model plant, knowledge about the genome sequences of ginger is extremely limited, and this limits molecular studies on this plant. In this study, de novo transcriptome sequencing was performed to investigate the expression of genes associated with the biosynthesis of major bioactive compounds in matured ginger rhizome (MG), young ginger rhizome (YG), and fibrous roots of ginger (FR). A total of 361,876 unigenes were generated by de novo assembly. The expression of genes involved in the pathways responsible for the biosynthesis of major bioactive compounds differed between tissues (MG, YG, and FR). Two pathways that give rise to volatile oil, gingerols, and diarylheptanoids, the “terpenoid backbone biosynthesis” and “stilbenoid, diarylheptanoid and gingerol biosynthesis” pathways, were significantly enriched (adjusted P value < 0.05) for differentially expressed genes (DEGs) (FDR < 0.005) both between the FR and YG libraries, and the FR and MG libraries. Most of the unigenes mapped in these two pathways, including curcumin synthase, phenylpropanoylacetyl-CoA synthase, trans-cinnamate 4-monooxygenase, and 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase, were expressed to a significantly higher level (log2 (fold-change) ≥ 1) in FR than in YG or MG. This study provides the first insight into the biosynthesis of bioactive compounds in ginger at a molecular level and provides valuable genome resources for future molecular studies on ginger. Moreover, our results establish that bioactive compounds in ginger may predominantly synthesized in the root and then transported to rhizomes, where they accumulate.

Abstract: Lignin is the main cause of lignocellulosic biomass recalcitrance to industrial enzymatic hydrolysis. By partially replacing the traditional lignin monomers by alternative ones, lignin extractability can be enhanced. To design a lignin that is easier to degrade under alkaline conditions, curcumin (diferuloylmethane) was produced in the model plant Arabidopsis thaliana via simultaneous expression of the turmeric (Curcuma longa) genes DIKETIDE-CoA SYNTHASE (DCS) and CURCUMIN SYNTHASE 2 (CURS2). The transgenic plants produced a plethora of curcumin- and phenylpentanoid-derived compounds with no negative impact on growth. Catalytic hydrogenolysis gave evidence that both curcumin and phenylpentanoids were incorporated into the lignifying cell wall, thereby significantly increasing saccharification efficiency after alkaline pretreatment of the transgenic lines by 14–24% as compared with the wild type. These results demonstrate that non-native monomers can be synthesized and incorporated into the lignin polymer in plants to enhance their biomass processing efficiency. A study introduces curcumin biosynthesis in Arabidopsis by expressing the turmeric genes DIKETIDE-CoA SYNTHASE and CURCUMIN SYNTHASE 2, and the monomers curcumin and phenylpentanoids were successfully incorporated into the lignin cell wall to enhance biomass processing.

Abstract: Curcuminoids are phenylpropanoids with high pharmaceutical potential. Herein, we report an engineered artificial pathway in Escherichia coli to produce natural curcuminoids through caffeic acid. Arabidopsis thaliana 4-coumaroyl-CoA ligase and Curcuma longa diketide-CoA synthase (DCS) and curcumin synthase (CURS1) were used to produce curcuminoids and 70 mg/L of curcumin was obtained from ferulic acid. Bisdemethoxycurcumin and demethoxycurcumin were also produced, but in lower concentrations, by feeding p-coumaric acid or a mixture of p-coumaric acid and ferulic acid, respectively. Additionally, curcuminoids were produced from tyrosine through the caffeic acid pathway. To produce caffeic acid, tyrosine ammonia lyase from Rhodotorula glutinis and 4-coumarate 3-hydroxylase from Saccharothrix espanaensis were used. Caffeoyl-CoA 3-O-methyltransferase from Medicago sativa was used to convert caffeoyl-CoA to feruloyl-CoA. Using caffeic acid, p-coumaric acid or tyrosine as a substrate, 3.9, 0.3, and 0.2 mg/L of curcumin were produced, respectively. This is the first time DCS and CURS1 were used in vivo to produce curcuminoids and that curcumin was produced by feeding tyrosine. We have shown that curcumin can be produced using a pathway involvoing caffeic acid. This alternative pathway represents a step forward in the heterologous production of curcumin using E. coli.

Abstract: Curcuminoids are well-known for their therapeutic properties. However, their extraction from natural sources is environmentally unfriendly, expensive and limited by seasonal variability, highlighting the need for alternative production processes. We propose an optimized artificial biosynthetic pathway to produce curcuminoids, including curcumin, in Escherichia coli. This pathway involves six enzymes, tyrosine ammonia lyase (TAL), 4-coumarate 3-hydroxylase (C3H), caffeic acid O-methyltransferase (COMT), 4-coumarate-CoA ligase (4CL), diketide-CoA synthase (DCS), and curcumin synthase (CURS1). Curcuminoids pathway was divided in two modules, the first module included TAL, C3H and COMT and the second one 4CL, DCS and CURS1. Optimizing the first module of the pathway, from tyrosine to ferulic acid, enabled obtaining the highest ferulic acid titer reported so far (1325.1 μM). Afterward, ferulic acid was used as substrate to optimize the second module of the pathway. We achieved the highest concentration of curcumin ever reported (1529.5 μM), corresponding to a 59.4% increase. Subsequently, curcumin and other curcuminoids were produced from tyrosine (using the whole pathway) in mono-culture. The production increased comparing to a previously reported pathway that used a caffeoyl-CoA O-methyltransferase enzyme (to convert caffeoyl-CoA to feruloyl-CoA) instead of COMT (to convert caffeic to ferulic acid). Additionally, the potential of a co-culture approach was evaluated to further improve curcuminoids production by reducing cells metabolic burden. We used one E. coli strain able to convert tyrosine to ferulic acid and another able to convert the hydroxycinnamic acids produced by the first one to curcuminoids. The co-culture strategies tested led to 6.6 times increase of total curcuminoids (125.8 μM) when compared to the mono-culture system. The curcuminoids production achieved in this study corresponds to a 6817% improvement. In addition, by using an inoculation ratio of 2:1, although total curcuminoids production decreased, curcumin production was enhanced and reached 43.2 μM, corresponding to an improvement of 160% comparing to mono-culture system. To our knowledge, these values correspond to the highest titers of curcuminoids obtained to date. These results demonstrate the enormous potential of modular co-culture engineering to produce curcumin, and other curcuminoids, from tyrosine.