Flavonols flavonol synthase

Figure 5.4. Abbreviated scheme for biosynthesis of major flavonoid subclasses, showing the primary enzymes and substrates leading to different subclasses. Bold-faced, uppercase abbreviations refer to enzyme names, whereas substrate names are presented in lowercase letters. PAL, phenylalanine ammonia lyase C4H, cinnamate 4-hydroxylase 4CL, 4-coumarate CoA ligase CHS, chalcone synthase CHI, chalcone isomerase CHR, chalcone reductase IPS, isoflavone synthase F3H, flavonone 3-hydroxylase F3 H, flavonoid 3 -hydroxylase F3 5 H, flavonoid 3 5 -hydroxylase FNSI/II, flavone synthase DFR, dihydroflavonol 4-reductase FLS, flavonol synthase ANS, anthocyanidin synthase LAR, leucoanthocyanidin reductase ANR, anthocyanidin reductase UFGT, UDP-glucose flavonoid 3-O-glucosyltransferase. R3 = H or OH. R5 = H or OH. Glc = glucose. Please refer to text for more information.

Owens DK, Alerding AB, Crosby KC, Bandara AB, Westwood JH and Winkel BSJ. 2008. Functional analysis of a predicted flavonol synthase gene family in Arabidopsis. Plant Physiol 147 1046-1061. 

Turnbull JJ, Nakajima J, Welford RW, Yamazaki M, Saito K and Schofield CJ. 2004. Mechanistic studies on three 2-oxoglutarate-dependent oxygenases of flavonoid biosynthesis anthocyanidin synthase, flavonol synthase, and flavanone 33-hydroxylase. J Biol Chem 279 1206-1216. 

Table 6.1 Abbreviations BAN, BANYULS bHLH, basic helix-loop-helix CHS, chalcone synthase CHI, chalcone isomerase DFR, dihydroflavonol reductase F3H, flavonol 3-hydroxylase F3 H, flavonoid 3 -hydroxylase FLS, flavonol synthase icx, increased chalcone synthase expression LDOX, leucoanthocyanidin dioxygenase LCR, leucoanthocyanidin reductase MATE, multidrug and toxic compound extrusion NR, not yet reported tt, transparent testa ttg, transparent testa glabrous the WD40 and WRKY transcription factors are named for conserved amino acid sequences within these proteins. PC = personal communication.

PELLETIER, M.K., MURRELL, J., SHIRLEY, B.W., Arabidopsis flavonol synthase and leucoanthocyanidin dioxygenase further evidence for distinct regulation of "early" and "late" flavonoid biosynthetic genes, Plant Physiol., 1997,113, 1437-1445. 

Flavonol synthase (FLS E.C.l.14.11.23) catalyzes the committed step in the production of fiavonols by introduction of a double bond between C2 and C3 of the corresponding dihydroflavonols. Like E3H, ELS has been described as a 2-oxoglutatarate-dependent dioxygenase based on its cofactor requirements for 2-oxoglutarate, Fe, and ascorbate. FLS was initially identified in enzyme preparations from illuminated parsley cell suspension cultures [67]. Subsequently, FLS was characterized from the flower buds of Matthiola incana and carnation (Dianthus caryophyllus L.), and it was suggested that there was regulation between flavonol and anthocyanidin biosynthesis [83, 84]. 

Halbwirth H, Fischer TC, Schlangen K, Rademacher W, Schleifer K, Forkmann G, Stitch K (2006) Screening for inhibitors of 2-oxoglutarate-dependent dioxygenases flavanone 3-hydroxylase and flavonol synthase. Plant Sd 171 194-205... 

Stitch K, Eidenberger T, Wurst F, Forkmann G (1992) Flavonol synthase activity and the regulation of flavonol and anthocyanin biosynthesis during flower development in Dianthus caryophyllus. Z Naturforsch 47C 553-560... 

Holton TA, Brugliera F, Tanaka Y (1993) Cloning and expression of flavonol synthase from Petunia hybrida. Plant J 4(6) 1003-1010... 

PeUetier MK, MurreU JR, Shirley BW (1997) Characterization of flavonol synthase and leucoanthocyanidin dioxygenase genes in arabidopsis. Further evidence for differential regulation of early and late genes. Plant Physiol 113(4) 1437-1445... 

Preuss A, Stracke R, Weisshaar B, Hfilebrecht A, Matem U, Martens S (2009) Arabidopsis thaliana expresses a second functional flavonol synthase. FEBS Lett 583(12) 1981-1986... 

WeUmann F, Lukacin R, Moriguchi T, Britsch L, SchUtz E, Matern U (2002) Eunctional expression and mutational analysis of flavonol synthase from Citrus unshiu. Eur 1 Biochem 269(16) 4134-4142... 

Prescott AG, Stamford NPl, Wheeler G, Firmin IL (2002) In vitro properties of a recombinant flavonol synthase from Arabidopsis thaliana. Phytochemistry 60 589-593... 

Lukacin R, WeUmann F, Britsch L, Martens S, Matern U (2003) Flavonol synthase from Citrus unshiu is a bifunctional dioxygenase. Phytochemistry 62(3) 287-292... 

RIBOFLAVIN KINASE FLAVONE SYNTHASE FLAVONOL SYNTHASE Flicker,... 

Much of the information on ANS has come not from studies on enzyme extracts but from analysis of DNA sequences and recombinant proteins. Sequences for the ANS were first isolated using transposon generated mutant lines of A. majus and Z. mays They encoded proteins of 40 to 41 kDa that were found to have similarity to 20GDs, during a study on a nonflavonoid enzyme. This sequence-based identification was confirmed by the in vitro assay of the recombinant Perilla frutescens protein, and subsequent assays on recombinant ANS from a range of species that confirmed the requirement for Fe, 20G, and ascorbate. Sequence comparisons show that ANS is more closely related to flavonol synthase (FLS), another 20GD, than to F3H. 

Nielsen, K.M. et al.. Antisense flavonol synthase alters copigmentation and flower color in lisianthus. Mol Breed., 9, 217, 2002. 

Davies, K.M. et al.. Enhancing anthocyanin production by altering competition for substrate between flavonol synthase and dihydroflavonol 4-reductase. Euphytica, 131, 259, 2003. 

Downey, M., Harvey, J., and Robinson, S., Synthesis of flavonols and expression of flavonol synthase genes in the developing grape berries of Shiraz and Chardonnay (Vitis vinifera L.). Aust. Grape Wine Res. 9, 110, 2003. 

Figure 1.36 Schematic diagram of the stilbene and flavonoid biosynthetic pathway. Enzyme abbreviations SS, stilbene synthase CHS, chalcone synthase CHR, chalcone reductase CHI, chalcone isomerase IFS, isoflavone synthase FNS, flavone synthase F3H, flavanone 3-hydroxylase FLS, flavonol synthase F3 H, flavonoid 3 -hydroxylase DFR, dihydroflavonol 4-reductase LAR, leucoanthocyanidin 4-reductase LDOX, leucocyanidin deoxygenase ANR, anthocyanidin reductase EU, extension units TU, terminal unit.

Scheme 1.1 Pathway for the biosynthesis of the major classes of flavonoids. 1, Chalcone synthase 2, chalcone isomerase 3, flavone synthase 4, flavanone 3-hydroxylase 5, flavonol synthase 6, dihydroflavonol reductase 7, anthocyanidin synthase 8, anthocyanidin glucosyltransferase 9, chalcone-ketide reductase 10, chalcone isomerase 11, isoflavone synthase 12, isoflavone 2 -hydroxylase 13, isoflavone reductase 14, pterocarpan synthase 15, pterocarpan 6a-hydroxylase 16, prenyltransferase 17, prenylcyclase.

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