Hydroxycinnamoyl-CoA : quinate

Rhodes, M.J.C., Wooltorton, L.S.C. and Lourenco, E.J. (1979) Purification and properties of hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase from potatoes. Phytochemistry, 18,1125-9. 

Figure 4 Current view of the phenylpropanoid pathway to the monolignols 19-23. 4CL, 4-hydroxycinnamate coenzyme Aligases pC3H , p-coumarate 3-hydroxylase C4H, cinnamate 4-hydroxylase CAD, cinnamyl alcohol dehydrogenases CCOMT, hydroxycinnamoyl CoA O-methyltransferases CCR, cinnamoyl-CoA oxidoreductases COMT, caffeic acid O-methyltransferases F5H , ferulate 5-hydroxylase HCT, hydroxycinnamoyl-CoA shikimate hydroxycinnamoyltransferase HOT, hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase PAL, phenylalanine ammonia lyase TAL, tyrosine ammonia lyase.

Ulbrich, B. and M.H. Zenk Partial purification and properties of hydroxycinnamoyl-CoA Quinate hydroxycin-namoyl transferase from higher plants Phytochemistry 18 (1979) 929-933. 

Lamb, C.J. (1977). Trans-cinnamic acid as mediator of the light stimulated increase in hydroxycinnamoyl-CoA quinate hydroxycinnamoyl-transferase. FEBS-Lett., 75, 37-40. 

Ulbrich, B., J. Stdckigt, and M.H. Zenk (1975). Induction by light of hydroxycinnamoyl-CoA-quinate-transferase activity in buckwheat hypocotyls. Naturwissenschaf-ten, 63. 484. 

Ulrich, B., and N. Amrhein (1978). Induction by light of hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase in buckwheat (Fagopyrum esculentum Moench) Absence of feed-forward control by trans-cinnamate. Plants, 138, 69-71. 

One example is probably cinnamic acid (D 22.2.1), which represses the formation of phenylalanine ammonia-lyase (PAL) and induces hydroxycinnamoyl CoA quinate hydroxycinnamoyl-transferase, an enzyme of chlorogenic acid biosynthesis. 

The substitution of the phenyl ring necessary for the biosynthesis of coniferyl alcohol (3.79) and sinapyl alcohol (3.81) begins with the hydroxylation of C3. This is a conversion that requires the formation of the ester of /5-coumaroyl-CoA with D-quinate (3.73) or shikimate (3.74) catalyzed by the enzyme hydroxycinnamoyl-CoA shikimate/quinate hydroxy-cinnamoyl transferase (HCT Hoffmann et al., 2003). The hydroxylation of this ester intermediate is catalyzed by the enzyme /i-coumarovl-Co A 3 -hydroxylase (C3 H Schoch et al., 2001 Franke et al., 2002a,b). The resulting shikimate or quinate ester (3.75 3.76) is subsequently hydrolyzed by the same HCT, resulting in caffeoyl-CoA (3.36). 

Figure 3-9. Biosynthesis of monolignols. The enzymes involved in this pathway are ( ) hydroxycinnamoyl-CoA shikimate/quinate hydroxy-cinnamoyl transferase, (b) p-coumaroyl-CoA 3 -hydroxylase (E.C. 1.14.14.1), (c) caffeoyl-CoA O-methy 1 Iranslerasc (E.C. 2.1.1.104), (d) cinnamoyl-CoA reductase (E.C. 1.2.1.44) (e) cinnamyl alcohol dehydrogenase (E.C. 1.1.1.195), (f) coniferyl aldehyde/coniferyl alcohol 5-hydroxylase (E.C. 1.14.13), (g) coniferaldehyde/coniferyl alcohol O-methyltransferase (E.C. 2.1.1.68).

Figure 4.1 Current view of the phenylpropanoid metabolism. PAL, phenylalanine ammonia-lyase C4H, cinnamate 4-hydroxylase 4CL, 4-coumarate CoA-ligase HCT, hydroxycinnamoyl-CoAishikimate/quinate hydroxycinnamoyltransferase 3-hydroxylase, 4-hydroxycinnamoylshikimate/quinate 3-hydroxylase.

HAL and PAL Proposed Tyr loop-in model for breathing motion tor substrate access The molecular basis of PAL and TAL substrate versatility Hydroxycinnamoyl CoA Shikimate/Quinate Hydroxycinnamoyltransferase Cytochrome P-450 Hydroxylation Reactions (Cinnamate 4-Hydroxylase, p-Coumarate 3-Hydroxylase , and Ferulate 5-Hydroxylase ) Comparison to Bacterial/Mammalian P-450s Subcellular localization of C4H, pC3H , and F5H ... 

Hydroxycinnamoyl CoAishikimate/quinate hydroxycinnamoyltransferase (HCT, EC 2.3.1.133) catalyzes esterification of shikimate (29) and quinate (28) with -coumaroyl CoA (9) to afford the corresponding esters 25 and 24, respectively. This biochemical conversion was discovered by Stockigt and Zenk, with later studies describing its partial purification and the reversibility of the enzymatic conversion. Interestingly, this step has now been established as the forerunner to the second hydroxylation (at C3) to ultimately afford caffeoyl CoA (10) (see Figure 4). As for PAL/TAL, this protein is considered cytosolic, as the enzyme contains... 

Figure 3.1 Primary flux of carbon through phenylpropanoid pathway in Arabidopsis. PAL, phenylalanine ammonia-lyase 4CL, 4-(hydroxy)cinnamoyl CoA ligase C4H, cinnamate 4-hydroxylase HCT, hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase C3 H, /7-coumaroylshikimate 3 -hydroxylase CCoAOMT, caffeoyl CoA O-methyltransferase F5H, ferulate 5-hydroxylase COMT, caffeic acid/5-hydroxyferulic acid o-methyltransferase CCR, cinnamoyl CoA reductase CAD, cinnamyl alcohol dehydrogenase. Not depicted is the HCT catalyzed synthesis of/r-coumaroyl quinate.

The BAHD superfamily is meanwhile divided into five or eight clades. Although the superfamily is growing fast, there are only three more crystal structures of BAHD enzymes which have been reported. Of them, the latest one is represented by HCT/HQT (hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl-transferase) from Coffea cane-phora. The native HCT has been biochemically and structurally well characterized. Meanwhile only two other structures have been described, an anthocyanin malonyltransferase and trichotecene acetyl-... 

The normal functioning of phenolic metabolism seems to require a cooperation between different organelles. Our results in Petunia leaves exemplify this possible participation of different compartments in the case of chloro-genlc acid biosynthesis (Ref. 29). Petunia chloroplasts are devoid of caffeate CoA-ligase activity but contain hydroxycinneunoyl-CoA quinate hydroxycinnamoyl-transferase. Moreover, chlorogenic acid is formed by isolated chloroplasts provided that the C6-C3 imlt is supplied as caffeoyl-CoA ester. 

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