The Function and Catalysis of 2-Oxoglutarate-Dependent Oxygenases Involved in Plant Flavonoid Biosynthesis

Abstract

Flavonoids are secondary metabolites derived from phenylalanine and acetate metabolism. They fulfil a variety of functions in plants and have health benefits for humans. During the synthesis of the tricyclic flavonoid natural products in plants, oxidative modifications to the central C ring are catalyzed by four of FeII and 2-oxoglutarate dependent (2-ODD) oxygenases, namely flavone synthase I (FNS I), flavonol synthase (FLS), anthocyanidin synthase (ANS) and flavanone 3β-hydroxylase (FHT). FNS I, FLS and ANS are involved in desaturation of C2–C3 of flavonoids and FHT in hydroxylation of C3. FNS I, which is restricted to the Apiaceae species and in rice, is predicted to have evolved from FHT by duplication. Due to their sequence similarity and substrate specificity, FLS and ANS, which interact with the α surface of the substrate, belong to a group of dioxygenases having a broad substrate specificity, while FNS I and FHT are more selective, and interact with the naringenin β surface. Here, we summarize recent findings regarding the function of the four 2-ODD oxygenases and the relationship between their catalytic activity, their polypeptide sequence and their tertiary structure.

Nonsense Mutation Inside Anthocyanidin Synthase Gene Controls Pigmentation in Yellow Raspberry (Rubus idaeus L.)

“…Among all 2-ODDs the catalytic residues are characterized by highly conserved histidine (His) residues for ferrous-iron coordination, and arginine (Arg) and serine (Ser) residues for binding site of 2-oxoglutarate and phenylalanine (Phe) residue for substrate binding (Saito et al, 1999; Koehntop et al, 2005; Clifton et al, 2006; Gebhardt et al, 2007; Cheng et al, 2014) as shown in Figure 2 . Molecular analysis of Ans gene at genomic and mRNA/cDNA level indicates a 5 bp insertion (GGCCT; ans +5 ) in “Anne” ans alleles ( Figure 2 ; Supplementary Figure S2).…”

The light‐induced transcription factor FtMYB116 promotes accumulation of rutin in Fagopyrum tataricum

“…Subsequently, CHI catalyses the conversion of naringenin chalcone to naringenin (Mona & Christopher, 1987), which is then converted to flavones, such as orientin and vitexin, through CGT catalysis (Nagatomo et al, 2014). Naringenin can also be converted to dihydrokaempferol and dihydroquercetin via F3H and F3′H, respectively (Cheng, Han, Wu, & Lou, 2014;Hagmann, Heller, & Grisebach, 1983). At this point, the pathway divides into two branches.…”

Catalytic Mechanisms of Fe(II)- and 2-Oxoglutarate-dependent Oxygenases

“…The Fe(II)/2OG-dependent oxygenases catalyze a variety of oxidative transformations including hydroxylation, halogenation, ring closure, desaturation, epimerization, ring expansion, and epoxidation reactions. Because of their rich oxidative transformation capabilities, these enzymes play important roles in many biological processes (9) including the post-translational modification of collagen (11), fatty acid metabolism (12,13), oxygen sensing (14,15), DNA and RNA repair (16,17), demethylations related to epigenetic regulation (18,19), and the biosynthesis of many antibiotics and other secondary metabolites (20,21).…”