Ferulate 5-hydroxylase

Humphreys, J. M. Hemm, M. R. Chappie, C. Ferulate 5-hydroxylase fromArahidopsis is a multifunctional cytochrome P450-dependent monooxygenase catalyzing parallel hydroxylations in phenylpropanoid metabolism. Proc. Natl. Acad Sci. USA 1999, 96, 10045-10050. 

Marita, J. Ralph, J. Hatfield, R. D. Chappie, C. NMR characterization of lignins in Arabidopsis altered in the activity of ferulate-5-hydroxylase. Proc. Natl. Acad. Sci. USA 1999, 96, 12328-12332. 

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.

Meyer, K., Cusumano, J. C., Sommerville, C., and Chappie, C. C. S., 1996, Ferulate-5-hydroxylase from Arabidopsis thaliana defines a new family of cytochrome P-450 dependent monooxygenases, Proc. Natl. Acad. Sci. USA 93 6869-6874. 

Figure 1.35 Schematic diagram of the phenolic biosynthetic pathway accompanied by the key enzymes involved. Enzyme abbreviations PAL, phenylalanine ammonia-lyase BA2H, benzoic acid 2-hydroxylase C4H, cinnamate 4-hydroxylase COMT-1, caffeic/5-hydroxyferulic acid O-methy I transferase 4CL, p-co um a ra te C o A ligase F5H, ferulate 5-hydroxylase GT, galloyltransferase ACoAC, acetylCoA carboxylase.

Franke, R., McMichael, C.M., Meyer, K., Shirley, A.M., Cusumano, J.C. and Chappie, C. (2000) Modified lignin in tobacco and poplar plants over-expressing the Arabidopsis gene encoding ferulate 5-hydroxylase. Plant., 22, 223-34. 

Sibout, R., Baucher, M., Gatineau, M., Van Doorsselaere, J., Mila, L, Pol-let, B., Mabaa, B., Pilatec, G., Lapierree, C., Boerjand, W. and Jouanin L. (2002) Expression of a poplar cDNA encoding a ferulate-5-hydroxylase/ coniferaldehyde 5-hydroxylase increases S lignin deposition in Arabidopsis thaliana. Plant Physiol. Biochem., 40,1087-96. 

L-Phenylalanine,which is derived via the shikimic acid pathway,is an important precursor for aromatic aroma components. This amino acid can be transformed into phe-nylpyruvate by transamination and by subsequent decarboxylation to 2-phenylacetyl-CoA in an analogous reaction as discussed for leucine and valine. 2-Phenylacetyl-CoA is converted into esters of a variety of alcohols or reduced to 2-phenylethanol and transformed into 2-phenyl-ethyl esters. The end products of phenylalanine catabolism are fumaric acid and acetoacetate which are further metabolized by the TCA-cycle. Phenylalanine ammonia lyase converts the amino acid into cinnamic acid, the key intermediate of phenylpropanoid metabolism. By a series of enzymes (cinnamate-4-hydroxylase, p-coumarate 3-hydroxylase, catechol O-methyltransferase and ferulate 5-hydroxylase) cinnamic acid is transformed into p-couma-ric-, caffeic-, ferulic-, 5-hydroxyferulic- and sinapic acids,which act as precursors for flavor components and are important intermediates in the biosynthesis of fla-vonoides, lignins, etc. Reduction of cinnamic acids to aldehydes and alcohols by cinnamoyl-CoA NADPH-oxido-reductase and cinnamoyl-alcohol-dehydrogenase form important flavor compounds such as cinnamic aldehyde, cin-namyl alcohol and esters. Further reduction of cinnamyl alcohols lead to propenyl- and allylphenols such as... 

Syringyl Lignin Pathways Two key enzymes (beyond the coniferyl alcohol pathway) are required for the production of sinapyl alcohol, which is the essential monolignol for production of syringyl units in lignins. Ferulate 5-hydroxylase, FH5, now perhaps more appropriately called CAld-5H to reflect coniferaldehyde as the preferred substrate [347,348], effects the 5-hydroxylation. Caffeate 0-methyltransferase,... 

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 ... 

Cinnamate 4-hydroxylase p-Coumarate 3-hydroxylase Ferulate 5-hydroxylase... 

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.

Cytochrome P-450 Hydroxylation Reactions (Cinnamate 4-Hydroxylase, p-Coumarate 3-Hydroxylase , and Ferulate 5-Hydroxylase ) Comparison to Bacterial/ Mammalian P-450s... 

Ferulate 5-hydroxylase (F5H) catalyzes the third P-450 hydroxylation step at the C5 position of the phenolic ring to ultimately afford, via the monolignol pathway, 5-hydroxyconiferyl (22) and/or sinapyl (23) alcohols. This P-450 was first detected in xylem and sclerenchyma-enriched tissues from poplar Populus x euramericana), with microsomal extracts able to catalyze hydroxylation of ferulic acid (6) to 5-hydroxyferulic acid (7) in the presence of NADPH with apparent values of 6.3 pmoll / This enzyme was thus characterized as F5H. 

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.

RUEGGER, M., MEYER, K., CUSUMANO, J.C., CHAPPLE, C., Regulation of ferulate-5-hydroxylase expression in Arahidopsis in the context of sinapate ester oiosynX cissis, Plant Physiol, 1999, 119, 101-110. 

Humphreys JM, Hemm MR, Chappie C (1999) New routes for lignin biosynthesis defined by biochemical chaiacterizalion of recombinant ferulate 5-hydroxylase, a multifunctional cytochrome P450-dependent monooxygenase. Proc Natl Acad Sci U S A 96 10045 10050... 

Figure 1. Proposed biosynthetic pathway to monolignols, and related metabolites, a. Phenylalanine ammonia-lyase, b. Tyrosine ammonia-lyase, c. Cinnamate-4-hydroxylase, d. p-Coumarate-3-hydroxylase, e. O-Methyltransferase, f. Ferulate-5-hydroxylase, g. Hydroxycinnamate-CoA ligase, h. Cinnamoyl-CoA NADP oxidoreductase, i. Cinnamyl alcohol dehydrogenase. ( Note plus acetate pathway for both flavonoids and suberin)...

Stewart, J. J., Akiyama, T, Chappie, C., Ralph, J., Mansfield, S. D. The effects on lignin stmcture of overexpression of ferulate 5-hydroxylase in hybrid poplar. Plant Physiology 2009, 150,621-635. 

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