Expression of bacterial tyrosine ammonia-lyase creates a novel p-coumaric acid pathway in the biosynthesis of phenylpropanoids in Arabidopsis

Abstract

Some flavonoids are considered as beneficial compounds because they exhibit anticancer or antioxidant activity. In higher plants, flavonoids are secondary metabolites that are derived from phenylpropanoid biosynthetic pathway. A large number of phenylpropanoids are generated from p-coumaric acid, which is a derivative of the primary metabolite, phenylalanine. The first two steps in the phenylpropanoid biosynthetic pathway are catalyzed by phenylalanine ammonia-lyase and cinnamate 4-hydroxylase, and the coupling of these two enzymes forms a rate-limiting step in the pathway. For the generation of p-coumaric acid, the conversion from phenylalanine to p-coumaric acid that is catalyzed by two enzymes can be theoretically performed by a single enzyme, tyrosine ammonia-lyase (TAL) that catalyzes the conversion of tyrosine to p-coumaric acid in certain bacteria. To modify the p-coumaric acid pathway in plants, we isolated a gene encoding TAL from a photosynthetic bacterium, Rhodobacter sphaeroides, and introduced the gene (RsTAL) in Arabidopsis thaliana. Analysis of metabolites revealed that the ectopic over-expression of RsTAL leads to higher accumulation of anthocyanins in transgenic 5-day-old seedlings. On the other hand, 21-day-old seedlings of plants expressing RsTAL showed accumulation of higher amount of quercetin glycosides, sinapoyl and p-coumaroyl derivatives than control. These results indicate that ectopic expression of the RsTAL gene in Arabidopsis enhanced the metabolic flux into the phenylpropanoid pathway and resulted in increased accumulation of flavonoids and phenylpropanoids.

Acclimation and interaction between drought and elevated UV‐B in A. thaliana: Differences in response over treatment, recovery and reproduction

“…The initial condition was A:B (5:95, v/v), and the percentage of B increased linearly to 50% over 45 min. Mass spectra were acquired in negative ionization mode, and compounds were identified by comparison of their molecular mass and fragmentation patterns with those reported for A. thaliana in the literature (Stobiecki et al 2006;Ringli et al 2008;Nishiyama et al 2010). Figure 2.…”

Strategies for the production of biochemicals in bioenergy crops

“…Biomass from bioenergy crops, especially grasses such as switchgrass, corn, and sorghum, contains nonnegligible amount of pCA which occurs on the hydroxyl group on the γ-carbon of lignin unit side chains, mostly on syringyl units [73]. Tyrosine ammonia-lyase (TAL) catalyzes the conversion of tyrosine into pCA, and expression of a bacterial TAL in Arabidopsis was sufficient to increase the accumulation of soluble pCA derivatives such as anthocyanins and flavonoids [74]. Therefore, higher content of pCA in cell wall biomass may be achieved by concomitantly boosting pCA production from tyrosine and promoting pCA transfer onto lignin monomers.…”

Bioprocess Optimization for the Production of Aromatic Compounds With Metabolically Engineered Hosts: Recent Developments and Future Challenges

“…p-Coumaric acid is an important platform chemical used as monomer of liquid crystal polymers for electronics (Kaneko et al, 2006), as well as precursor for the synthesis of polyphenols (Rodriguez et al, 2015). The route for their production starts with L-Phe and L-Tyr deamination to further produce the phenylpropanoid cinnamic acid and p-coumaric acid, respectively, by the activity of phenylalanine ammonia lyase (PAL) (MacDonald and D'Cunha, 2007) and tyrosine ammonia lyase (TAL) (Nishiyama et al, 2010; Figure 2). The enzyme P450 monooxygenase cinnamate 4-hydroxylase (C4H) can further oxidize the cinnamic acid yielding the p-coumaric acid (Rasmussen et al, 1999;Achnine et al, 2004).…”