@entity523 ( @entity523 ), like other Solanaceous species, accumulates high levels of antioxidant caffeoylquinic acids, which are strong bioactive molecules and protect plants against biotic and abiotic stresses. Among these compounds, the monocaffeoylquinic acids (e.g. @entity13259 [CGA]) and the dicaffeoylquinic acids (diCQAs) have been found to possess marked antioxidative properties. Thus, they are of therapeutic interest both as phytonutrients in foods and as pharmaceuticals. Strategies to increase diCQA content in plants have been hampered by the modest understanding of their biosynthesis and whether the same pathway exists in different plant species. Incubation of CGA with crude extracts of @entity523 fruits led to the formation of two new products, which were identified by liquid chromatography-mass spectrometry as diCQAs. This @entity68298 : @entity68298 transferase activity was partially purified from ripe fruit. The final protein fraction resulted in 388-fold enrichment of activity and was subjected to trypsin digestion and mass spectrometric sequencing: a hydroxycinnamoyl-Coenzyme A:quinate hydroxycinnamoyl transferase (HQT) was selected as a candidate protein. Assay of recombinant HQT protein expressed in @entity526 confirmed its ability to synthesize diCQAs in vitro. This second activity ( @entity68298 : @entity68298 transferase) of HQT had a low pH optimum and a high Km for its substrate, CGA. High concentrations of CGA and relatively low pH occur in the vacuoles of plant cells. Transient assays demonstrated that @entity523 HQT localizes to the vacuole as well as to the cytoplasm of plant cells, supporting the idea that in this species, the enzyme catalyzes different reactions in two subcellular compartments.

Dual catalytic activity of hydroxycinnamoyl-coenzyme a quinate transferase from XXXX allows it to moonlight in the synthesis of both mono- and dicaffeoylquinic acids.

@entity523 :: ('4081', 'Species') :: ['tomato', 'Solanum lycopersicum', 'Tomato'] @entity13259 :: ('MESH:D002726', 'Chemical') :: ['chlorogenic acid'] @entity68298 :: ('CHEBI:16112', 'Chemical') :: ['chlorogenate'] @entity526 :: ('562', 'Species') :: ['Escherichia coli']
@entity523 :: (4081,Species) :: ['tomato']
