Caffeoyl-CoA O-methyltransferase

Figure 3-4. The general phenylpropanoid pathway. The enzymes involved in this pathway are (a) phenylalanine ammonia lyase (PAL E.C. 4.3.1.5), (b) cinnamic acid 4-hydroxylase (C4H E.C. 1.14.13.11), and (J) 4-coumaric acid CoA ligase (4CL E.C. 6.2.1.12). (a) depicts tyrosine ammonia lyase activity in PAL of graminaceous species. The grey structures in the box represent an older version of the phenylpropanoid pathway in which the ring substitution reactions were thought to occur at the level of the hydroxycinnamic acids and/or hydroxycinnamoyl esters. The enzymes involved in these conversions are (c) coumarate 3-hydroxylase (C3H E.C. 1.14.14.1), (d) caffeate O-methyltransferase (COMT EC 2.1.1.68), (e) ferulate 5-hydroxylase (F5H EC 1.14.13), and (g) caffeoyl-CoA O-methyltransferase (CCoA-OMT EC 2.1.1.104). These enzymes are discussed in more detail in Section 10.

Figure 1.37 Proposed biosynthetic pathway of curcuminoids in tumeric. Enzyme abbreviations CCOMT, caffeoyl-CoA O-methyltransferase 4CL, 4-coumarate CoA ligase CST, shikimate transferase CS3 H, p-coumaroyl 5-O-shikimate 3 -hydroxylase OMT, O-methyltransferase PKS, polyketide synthase. [Adapted from Ramirez-Ahumada et al. (2006)]...

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.

Guo, D., Chen, R, Inoue, K., Blount, J.W. and Dixon, R.A. (2001) Downregulation of caffeic acid 3-O-methyltransferase and caffeoyl CoA 3-O-methyltransferase in transgenic alfalfa Impacts on lignin structure and implications for the biosynthesis of G and S lignin. Plant Cell, 13, 73-88. 

Schmitt, D., Pakusch, A.E. and Matem, U. (1991) Molecular cloning, induction and taxonomic distribution of caffeoyl-CoA 3-O-methyltransferase, an enzyme involved in disease resistance.. Biol. Chem., 266,17416-23. 

KUHNL, T KOCH, U., HELLER, W., WELLMANN, E., Elicitor Induced S-Adenosyl-L-Methionine - Caffeoyl-Coa 3-O-Methyltransferase from Carrot Cell-Suspension Cultures, Plant Science, 1989,60,21-25. 

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