title: Novel hydroxycinnamoyl-coenzyme A quinate transferase genes from artichoke are involved in the synthesis of chlorogenic acid.
abstract: Artichoke (Cynara cardunculus subsp. scolymus) extracts have high antioxidant capacity, due primarily to flavonoids and phenolic acids, particularly chlorogenic acid (5-caffeoylquinic acid [CGA]), dicaffeoylquinic acids, and caffeic acid, which are abundant in flower bracts and bioavailable to humans in the diet. The synthesis of CGA can occur following different routes in plant species, and hydroxycinnamoyl-coenzyme A transferases are important enzymes in these pathways. Here, we report on the isolation and characterization of two novel genes both encoding hydroxycinnamoyl-coenzyme A quinate transferases (HQT) from artichoke. The recombinant proteins (HQT1 and HQT2) were assayed after expression in Escherichia coli, and both showed higher affinity for quinate over shikimate. Their preferences for acyl donors, caffeoyl-coenzyme A or p-coumaroyl-coenzyme A, were examined. Modeling and docking analyses were used to propose possible pockets and residues involved in determining substrate specificities in the HQT enzyme family. Quantitative real-time polymerase chain reaction analysis of gene expression indicated that HQT1 might be more directly associated with CGA content. Transient and stable expression of HQT1 in Nicotiana resulted in a higher production of CGA and cynarin (1,3-dicaffeoylquinic acid). These findings suggest that several isoforms of HQT contribute to the synthesis of CGA in artichoke according to physiological needs and possibly following various metabolic routes.
authors.affiliation: Institute of Plant Genetics, National Research Council, 70126 Bari, Italy. gabriella.sonnante@igv.cnr.it
authors.forename: Gabriella
authors.initials: G
authors.lastname: Sonnante
authors.forename: Rosalinda
authors.initials: R
authors.lastname: D'Amore
authors.forename: Emanuela
authors.initials: E
authors.lastname: Blanco
authors.forename: Ciro L
authors.initials: CL
authors.lastname: Pierri
authors.forename: Monica
authors.initials: M
authors.lastname: De Palma
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.forename: Marina
authors.initials: M
authors.lastname: Tucci
authors.forename: Cathie
authors.initials: C
authors.lastname: Martin
mesh_terms: D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002726:Chlorogenic Acid / Q000378:metabolism*; D031943:Cynara scolymus / Q000201:enzymology* / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D057075:Enzyme Assays; D004926:Escherichia coli / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA; D040681:Structural Homology, Protein; D014026:Nicotiana / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D002726:Chlorogenic Acid; D000217:Acyltransferases; C021394:hydroxycinnamoyl-CoA-quinate transferase