Isoflavonoid biosynthesis

STEELE, C.L., GLJZEN, M., QUTOB, D., DIXON, R.A., Molecular characterization of the enzyme catalyzing the aryl migration reaction of isoflavonoid biosynthesis in soybean, Arch. of Biochem. and Biophys., 1999, 367, 146-150. 

Modification of isoflavonoid biosynthesis may have a wide range of applications for improving not only plant defense characters but also the health benefits of food for humans. With the exception of IFD (which may not be required in vivo), cDNA clones are available for all of the enzymes needed for the production of the isoflavonoid vestitone. Furthermore, as VR cDNAs have been cloned, only clones for the DMID are lacking for the biosynthetic branch of the antifungal pterocarpans. To date, experiments have focused on 2HIS, but there has also been success using IFR, I2 H, and I70MT. 

Deavours BE, Dixon RA. 2005. Metabolic engineering of isoflavonoid biosynthesis in alfalfa. Plant Physiol 138 2245-2259. 

Dixon RA, Choundhary AD, Dalkin K, Edwards R, Fahrendorf T, Gowni G, Harrison MJ, Lamb CJ, Loake GJ, Maxwell CA, Orr J, Paiva NL. 1992. Molecular biology of stress-induced phenylpropanoid and isoflavonoid biosynthesis in alfalfa. In Stafford HA, Ibrahim RK, Eds. Phenolic Metabolism in Plants. New York Plenum, pp. 91-138. 

Farag MA, Huhman DV, Dixon RA, Sumner LW. 2008. Metabolomics reveals novel pathways and differential mechanistic and elicitor-specific responses in phenylpropanoid and isoflavonoid biosynthesis in Medicago truncatula cell cultures. Plant Physiol 146 387 402. 

The branch pathway for anthocyanin biosynthesis starts with the enzymatic reduction of dihydrofiavonols to their corresponding flavan 3,4-diols (leucoanthocyanidins) by substrate-specific dihydroflavonol 4-reductases (DFR). Flavan 3,4-diols are the immediate precursors for the synthesis of catechins and proanthocyanidins. Catechins are formed by enzymatic reduction of the flavan 3,4-diols in the presence of NADPH to leucoanthocyanidins, which are subsequently converted to anthocyanidins by the 2-oxoglutarate-dependant dioxygenase, anthocyanidin synthase. Further glycosylation, methylation, and/or acylation of the latter lead to the formation of the more stable, colored anthocyanins (Scheme 1.1). The details of the individual steps involved in flavonoid and isoflavonoid biosynthesis, including the biochemistry and molecular biology of the enzymes involved, have recently appeared in two excellent reviews.7,8... 

Bearing these taxonomic conclusions in mind, an overview of likely biosynthetic relationships between the isoflavonoids discussed in this chapter was proposed [6] and is represented in Fig. (4). This emphasises those compounds whose occurrence is restricted to the 3 species in the proposed series Pinnatifida (C. bijugum, C. judaicum and C. pinnatifidum) and attempted to address the biosynthesis of these compounds, most notably arybenzofurans which are still missing from the latest versions of the isoflavonoid biosynthesis schemes because of the lack of persuasive biogenetic evidence. A 2 -hydroxyisoflavanol, the immediate precursor of isoflav-3-enes and pterocarpans, is shown as the first intermediate. Its... 

Molecular characterization of the enzyme catalysing the aryl migration reaction of isoflavonoid biosynthesis in soybean. Arch. Biochem. Biophys. 367, 146—150. 

Control of glyceollln formation appears to involve large coordinate Increases in the activities of several enzymes of phenylpropanold metabolism. Despite our limited knowledge of isoflavonoid biosynthesis, evidence reported here favors the idea that control of glyceollln biosynthesis is dependent on the interplay of general phenylpropanold metabolism and its more specialized branch, the so far mainly vmknown isoflavonoid pathway. 

Ralston L, Subramanian S, Matsuno M, Yu O (2005) Partial reconstruction of ilavraioid and isoflavonoid biosynthesis in yeast using soybean type I and type II chaleoneisomeiases. Plant Physiol 137 1375-1388. doi 10.1104/pp.l04.054502... 

Du H, Huang Y, Tang Y (2010) Genetic and metabolic engineering of isoflavonoid biosynthesis. Appl Microbiol Biotechnol 86 1293-1312... 

Fig. 2.6 An overview of isoflavonoid biosynthesis in the Leguminosae based on recent findings. Partially characterized or uncertain steps are shown by the dotted arrows. 2HIS, 2-hydroxyisoflavanone synthase 2 OMT, 2 -0-methyltransferase (presumed) DMID, 7,2 -dihydroxy-4 -methoxyisoflavanol dehydratase HI4 OMT, hydroxyiso-flavanone 4 -0-methyltransferase I2 H, isoflavone 2 -hydroxylase IFR, isoflavone reductase PTR, pterocarpan reductase VR, vestitone reductase.

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