Proanthocyanidins biosynthesis

In spite of the recent progress in understanding the biosynthesis of the major building blocks of proanthocyanidins, (-l-)-catechin and (-)-EC, some important questions still remain to be elucidated (e.g., the exact nature of the molecular species that undergo polymerization and the mechanisms of assembly). The biosynthetic pathways for proanthocyanidins have been extensively reviewed [23-28]. A general scheme summarizing proanthocyanidin biosynthesis adapted from [27] and [28] is reported in Fig. 5. 

Xie and Dixon [27] underlined that although some models of proanthocyanidin biosynthesis show the extension units arising from condensation of an leucoanthocyanidin-derived electrophile with the nucleophilic 8 or 6 position of the starter unit, this scheme fails because of stereochemistry of leucoanthocyanidin is most likely 2,3-trans, whereas, in many cases, the extension units are 2,3-cis. One possible solution for this stereochemical para-... 

Xie DY and Dixon RA. 2005. Proanthocyanidin biosynthesis—still more questions than answers Phytochemistry 66 2127-2144. 

Tanner, G.J. et al., Proanthocyanidin biosynthesis in plants. Purification of legume leucoantho-cyanidin reductase and molecular cloning of its cDNA. J. Biol. Chem., 278, 31647, 2003. 

Baudry, A. et al., TT2, TT8, and TTGl synergistically specify the expression of BANYULS and proanthocyanidin biosynthesis in Arabidopsis thaliana. Plant J., 39, 366, 2004. 

Pang Y, Peel G, Wright E, Wang Z, Dixon RA. 2007. Early steps in proanthocyanidin biosynthesis in the model legume Medicago truncatula. Plant Physiol 145 601-615. 

Paolocci F, Robbins MP, Madeo L, Arcioni S, Martens S, Damiani F. 2007. Ectopic expression of a basic helix-loop-helix gene transactivates parallel pathways of proanthocyanidin biosynthesis. Structure, expression, analysis, and genetic control of leucoanthocyanidin 4-reductase and anthocyanidin reductase genes in Lotus corniculatus. Plant Physiol 143 504-516. 

Ikegami A, Eguchi S, Kitajima A, Inoue K, Yonemori K. 2007. Identification of genes involved in proanthocyanidin biosynthesis of persimmon (Diospyros kaki) fruit. Plant Sci 172 1037-1047. 

Stafford HA. 1989. The cnzymology of proanthocyanidin biosynthesis. In Hemingway RW, Karchesy JJ, Eds. Chemistry and Significance of Condensed Tannins. New York Plenum Press, pp. 345-368. 

Proanthocyanidin biosynthesis Arabidopsis thaliana TT2 TT8 TTG1 TTG2 (WRKY), TT1 (WIP zinc finger)... 

The proanthocyanidins share a biosynthesis sequence with the anthocyanins, a class of flavanoids well understood in biochemical and genetic terms. Three enzymes, leucoanthocyanidin reductase (LAR), anthocyanidin synthase (ANS), and anthocyanidin reductase (ANR), function at branches between the anthocyanin and proanthocyanidin biosynthesis pathways (Scheme 1). LAR is a member of the reductase—eptmerase—dehydrogenase enzyme... 

H. A. Stafford, The Enzymoiogy of Proanthocyanidin Biosynthesis, in Chemistry and Significance of Condensed Tannins, R. W. Hemingway, J. J. Karchesy, Eds. Pienum Press New York, 1989 p 4. 

Many steps of proanthocyanidin biosynthesis have recently been reviewed [59]. The genes encoding the key enzymes of biosynthesis of flavonols, the transport... 

Stafford, H.A. (1989). The enzymology of proanthocyanidin biosynthesis. In Chemistry and Significance of Condensed Tannins (eds R.W. Hemingway J.J. Karchesy), pp. 47-70. Plenum Press, New York. 

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