A tyrosine aminotransferase involved in rosmarinic acid biosynthesis in Prunella vulgaris L

Abstract

Rosmarinic acid (RA) and its derivants are medicinal compounds that comprise the active components of several therapeutics. We isolated and characterised a tyrosine aminotransferase of Prunella vulgaris (PvTAT). Deduced PvTAT was markedly homologous to other known/putative plant TATs. Cytoplasmic localisation of PvTAT was observed in tobacco protoplasts. Recombinantly expressed and purified PvTAT had substrates preference for L-tyrosine and phenylpyruvate, with apparent K m of 0.40 and 0.48 mM, and favoured the conversion of tyrosine to 4-hydroxyphenylpyruvate. In vivo activity was confirmed by functional restoration of the Escherichia coli tyrosine auxotrophic mutant DL39. Agrobacterium rhizogenes-mediated antisense/sense expression of PvTAT in hairy roots was used to evaluate the contribution of PvTAT to RA synthesis. PvTAT were reduced by 46–95% and RA were decreased by 36–91% with low catalytic activity in antisense transgenic hairy root lines; furthermore, PvTAT were increased 0.77–2.6-fold with increased 1.3–1.8-fold RA and strong catalytic activity in sense transgenic hairy root lines compared with wild-type counterparts. The comprehensive physiological and catalytic evidence fills in the gap in RA-producing plants which didn’t provide evidence for TAT expression and catalytic activities in vitro and in vivo. That also highlights RA biosynthesis pathway in P. vulgaris and provides useful information to engineer natural products.

Chitosan enhances rosmarinic acid production in shoot cultures of Melissa officinalis L. through the induction of methyl jasmonate

“…However, various reports indicate the role of one of two branching pathways in the biosynthesis of rosmarinic acid. Some of them showed that the biosynthesis of RA and phenolic compounds were correlated with TAT but not PAL activity (for example: Yan et al 2006; Lu et al 2013; Zhang et al 2014; Ru et al 2017), and the others conversely showed the involvement of PAL-derived pathway (for example: Mizukami et al 1992; Kim et al 2013). TAT is presumed to have a role in RA accumulation.…”

General and specialized tyrosine metabolism pathways in plants

“…For instance, an opium poppy (Papaver somniferum) TAT was shown to participate in the production of benzylisoquinoline alkaloids, including morphine and codeine (Lee and Facchini 2011). In Prunella vulgaris, a Traditional Chinese Medicinal (TCM) plant in the family of Lamiaceae, TAT is involved in the biosynthesis of RA (Ru et al 2017).…”

Antioxidant Effects and Cytoprotective Potentials of Herbal Tea against H2O2-Induced Oxidative Damage by Activating Heme Oxygenase1 Pathway

“…In this study, we identified six phenolic acids from WHT, and they all exhibited high antioxidant activity, which is consistent with the results from previous research [ 14 , 23 , 24 ]. Among these phenolic acids, rosmarinic acid had the highest content and the highest contribution ratio to the antioxidant activity of WHT, which is a major component of Prunella vulgaris (a raw material of WHT) [ 25 ]. However, total antioxidant activity of all six phenolic acids only contributed to 9.6% of DPPH radical scavenging activity and 13.6% of FRAP activity of WHT.…”