Functional characterization of two p-coumaroyl ester 3′-hydroxylase genes from coffee tree: Evidence of a candidate for chlorogenic acid biosynthesis

University of Strasbourg, Strasburg, Alsace, France
Plant Molecular Biology (Impact Factor: 4.26). 06/2007; 64(1-2):145-59. DOI: 10.1007/s11103-007-9141-3
Source: PubMed


Chlorogenic acid (5-CQA) is one of the major soluble phenolic compounds that is accumulated in coffee green beans. With other hydroxycinnamoyl quinic acids (HQAs), this compound is accumulated in particular in green beans of the cultivated species Coffea canephora. Recent work has indicated that the biosynthesis of 5-CQA can be catalyzed by a cytochrome P450 enzyme, CYP98A3 from Arabidopsis. Two full-length cDNA clones (CYP98A35 and CYP98A36) that encode putative p-coumaroylester 3'-hydroxylases (C3'H) were isolated from C. canephora cDNA libraries. Recombinant protein expression in yeast showed that both metabolized p-coumaroyl shikimate at similar rates, but that only one hydroxylates the chlorogenic acid precursor p-coumaroyl quinate. CYP98A35 appears to be the first C3'H capable of metabolising p-coumaroyl quinate and p-coumaroyl shikimate with the same efficiency. We studied the expression patterns of both genes on 4-month old C. canephora plants and found higher transcript levels in young and in highly vascularized organs for both genes. Gene expression and HQA content seemed to be correlated in these organs. Histolocalization and immunolocalization studies revealed similar tissue localization for caffeoyl quinic acids and p-coumaroylester 3'-hydroxylases. The results indicated that HQA biosynthesis and accumulation occurred mainly in the shoot tip and in the phloem of the vascular bundles. The lack of correlation between gene expression and HQA content observed in some organs is discussed in terms of transport and accumulation mechanisms.

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    • "diCQAs and triCQAs also accumulate in tomato fruit (diCQAs, approximately 2 mg 100 g –1 DW; and triCQAs, 1–2 mg 100 g –1 DW;Chanforan et al., 2012). Three pathways (Villegas and Kojima, 1986;Hoffmann et al., 2003;Niggeweg et al., 2004) have been proposed for the synthesis of CGA: (1) the direct pathway involving caffeoyl-CoA transesterification with quinic acid by hydroxycinnamoyl-Coenzyme A:quinate hydroxycinnamoyl transferase (HQT;Niggeweg et al., 2004;Comino et al., 2009;Menin et al., 2010;Sonnante et al., 2010); (2) the route by which p-coumaroyl-CoA is first transesterified with quinic acid via hydroxycinnamoyl- Coenzyme A transferase (HCT) acyltransferase (Hoffmann et al., 2003;Comino et al., 2007), followed by the hydroxylation of p-coumaroyl quinate to 5-caffeoylquinic acid, catalyzed by C39H (p-coumaroyl-3-hydroxylase;Schoch et al., 2001;Mahesh et al., 2007;Moglia et al., 2009); and (3) the use of caffeoyl-glucoside as the acyldonor (Villegas and Kojima, 1986). In tomato, the synthesis of CGA involves transesterification of caffeoyl-CoA with quinic acid by HQT (Niggeweg et al., 2004). "
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    • "The general phenylpropanoid-and monolignol-specific pathways also provide hydroxycinnamic acids, which include p-coumaric, caffeic, ferulic and sinapic acids. Hydroxycinnamic acids can be esterified or amidated by a variety of moieties such as malate, quinate, glucose, sucrose, choline, putrescine, spermidine, hydroxyanthranilate and tyramine; this can differ between plant species and plant tissues (Dimberg et al., 1993; Martin-Tanguy, 1997; Schmidt et al., 1999; Mahesh et al., 2007; Milkowski & Strack, 2010). In Arabidopsis, the largest portion of the ferulic and sinapic acid pool is made from coniferaldehyde and sinapaldehyde via hydroxycinnamaldehyde dehydrogenase (HCALDH) (Nair et al., 2004). "

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