Substrate promiscuity of acyltransferases contributes to the diversity of hydroxycinnamic acid derivatives in purple coneflower

Abstract

Hydroxycinnamic acid derivatives (HADs) such as chicoric acid are the main active ingredients of purple coneflower (Echinacea purpurea (L.) Moench). Recently, the biosynthesis of chicoric acid catalyzed by both BAHD and serine carboxypeptidase-like (SCPL) acyltransferases has been elucidated. However, the diversity of HADs in purple coneflower and their biosynthesis pathways remain unclear. Here, through an alignment of extract ion chromatograms of potential fragments, tentative HADs, such as phaselic acid and chicoric acid analogs (deoxy-and methyl-), were found in purple coneflower. Phylogenetic analyses based on the fulllength transcriptome were conducted to explore additional BAHD and SCPL acyltransferases that might be involved in HAD biosynthesis. One BAHD, conserved among Echinacea species, showed weak hydroxycinnamoyl-CoA:tartaric acid hydroxycinnamoyl transferase (HTT) activity. Further results indicated that this BAHD was hydroxycinnamoyl-CoA:malic acid hydroxycinnamoyl transferase (HMT), which catalyzes the biosynthesis of phaselic acid. Although no potential isozyme was found for chicoric acid synthase (CAS), CAS itself showed acyl acceptor promiscuity and catalyzed the biosynthesis of deoxychicoric acid and methylchicoric acid. Overall, we identified additional HADs and depicted their biosynthesis network in purple coneflower. The substrate promiscuity of identified acyltransferases diversifies HADs, indicating the complexity of plant secondary metabolism.

Understanding the mechanism of red light-induced melatonin biosynthesis facilitates the engineering of melatonin-enriched tomatoes

“…The assay was performed according to the method described by Fu et al 62 , 63 . The subject sequence was introduced into the pDEST17 vector by the Gateway system.…”

Deep learning and targeted metabolomics‐based monitoring of chewing insects in tea plants and screening defense compounds

“…Phylogenetic analysis was used to better understand the substrate promiscuity of homologous HCT sequences from different species in hydroxycinnamic acid metabolism (Figure 4a). It is not surprising that the diversity of hydroxycinnamic acid derivatives in purple coneflower is caused by the substrate promiscuity of acyltransferase (Fu et al, 2022). EpBAHDs also showed the substrate disorder of donors and acceptors and led to the biosynthesis of various simple hydroxycinnamic acid derivatives (Fu et al, 2021).…”

EpMYB2 positively regulates chicoric acid biosynthesis by activating both primary and specialized metabolic genes in purple coneflower

“…Co-expression analysis among metabolites, structural genes, and TFs has been widely used for the identification of intermediate substrates, biosynthetic genes, and regulators (Fu et al, 2022;Hong et al, 2022;Jin et al, 2024;Li et al, 2020;Reed et al, 2023;Ren et al, 2022;Yuan et al, 2022). We then used the six highly correlated chicoric acid biosynthetic genes as baits for co-expression analysis.…”