This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Secondary Metabolites Biosynthesis → Phenylpropanoid Derivatives Biosynthesis → Flavonoids Biosynthesis → Anthocyanins Biosynthesis|
Expected Taxonomic Range: Magnoliophyta
Polyacylated anthocyanins are widespread among flowering plants [Honda02] as exemplified by salvianin (this pathway) [Kondo89] and malonylshisonin (shisonin biosynthesis) [Takeda86], which are found in Labiatae and by cyanidin 3-O-(3'',6''-O-dimalonyl-β-glucopyranoside) [Nakayama97], which has been detected in the Asteraceae.
The varying flower coloration of Salvia has been investigated and found to be dependent on the distribution of anthocyanins, or more precisely of the backbone compounds that formed those anthocyanins. Red to pink-coloured flowers contain pelargonidin derived anthocyanins whereas blue and violet flowers are composed of delphinidin and cyanidin building blocks, respectively [Lu02].
Salvianin, the predominant anthocyanin causing the scarlet flower coloration of Salvia splendens has two malonyl groups linked to the 4" and 6"-hydroxyl groups of the 5-glucosyl moiety [Lu02] [Kondo89]. Its biosynthesis represents a species-specific variety of the decoration of pelargonin (compare pelargonidin conjugates biosynthesis) that involves glucosylation and aromatic and aliphatic acylation to increase stability, solubility and color variation of the chromophoric anthocyanins [Yamazaki99] [YonekuraSakakib00] [Heller94].
About This Pathway
Pelargonidin 3-O-β-D-glucoside represents the starting compound that is stepwise converted into bisdemalonylsalvianin, the precursor for the aliphatic acylation with malonyl-CoA. Those reactions involve 5-O-glucosylation [Yamazaki99] and 3-aromatic acylation with caffeic acid [Fujiwara98] [YonekuraSakakib00] which may proceed via two parallel pathway branches. The exact metabolic succession is not known and possibly will depend on the species involved.
Bisdemalonylsalvianin is further malonylated twice on its 5-O-glucosidic moiety which is carried out by two different regio-specific malonyltransferases [Suzuki01a] [Suzuki04a]. Both acyltransferases belong to the BAHD group [DAuria06] that constitutes a large family of acyl CoA-utilizing enzymes of high catalytic versatility which often includes numerous homologs of unknown biochemical functions [Dudareva00]. Although acetyltransferases show low similarities with each other they possess highly conserved sequences indicating the evolvement from a common ancestral gene [StPierre98].
The reaction mechanism of the first enzyme, i.e. malonyl-CoA: anthocyanin 5-O-glucoside-6'''-O-malonyltransferase (Ss5MaT1) producing monodemalonylsalvianin has been studied in detail revealing a ternary complex mechanism where both substrates and the enzyme must form a complex before catalysis can take place [Suzuki03]. The second malonylation forming salvianin is catalyzed by malonyl CoA: anthocyanin 5-O-glucoside-4'''-O-malonyltransferase (Ss5MaT2), an enzyme that despite its close substrate similarity evolved from a different branch of the BAHD family [Suzuki04a]. This enzyme is more related to acetyl-CoA:benzylalcohol acetyltransferase (BEAT) and thus differs from Ss5MaT1 associated with the anthocyanin acyltransferase (AAT) family.
Fujiwara98: Fujiwara H, Tanaka Y, Fukui Y, Ashikari T, Yamaguchi M, Kusumi T (1998). "Purification and characterization of anthocyanin 3-aromatic acyltransferase from Perilla frutescens." Plant Science, 137, 87-94.
Heller94: Heller W, Forkmann G (1994). "Biosynthesis of flavonoids." In: Harborne JB (editor) The flavonoids. Advances in research since 1986. Chapman & Hall, London Glasgow New York Tokyo Melbourne Madras, 499-537.
Nakayama97: Nakayama M, Koshioka M, Shibata M, Hiradate S, Sugie H, Yamaguchi MA (1997). "Identification of cyanidin 3-O-(3",6"-O-dimalonyl-β-glucopyranoside) as a flower pigment of chrysanthemum (Dendranthema grandiflorum)." Biosci. Biotech. Biochem., 61(9), 1607-1608.
StPierre98: St-Pierre B, Laflamme P, Alarco AM, De Luca V (1998). "The terminal O-acetyltransferase involved in vindoline biosynthesis defines a new class of proteins responsible for coenzyme A-dependent acyl transfer." Plant J 14(6);703-13. PMID: 9681034
Suzuki01a: Suzuki H, Nakayama T, Yonekura-Sakakibara K, Fukui Y, Nakamura N, Nakao M, Tanaka Y, Yamaguchi MA, Kusumi T, Nishino T (2001). "Malonyl-CoA:anthocyanin 5-O-glucoside-6"'-O-malonyltransferase from scarlet sage (Salvia splendens) flowers. Enzyme purification, gene cloning, expression, and characterization." J Biol Chem 276(52);49013-9. PMID: 11598135
Suzuki03: Suzuki H, Nakayama T, Nishino T (2003). "Proposed mechanism and functional amino acid residues of malonyl-CoA:anthocyanin 5-O-glucoside-6'''-O-malonyltransferase from flowers of Salvia splendens, a member of the versatile plant acyltransferase family." Biochemistry 42(6);1764-71. PMID: 12578391
Suzuki04a: Suzuki H, Sawada S, Watanabe K, Nagae S, Yamaguchi MA, Nakayama T, Nishino T (2004). "Identification and characterization of a novel anthocyanin malonyltransferase from scarlet sage (Salvia splendens) flowers: an enzyme that is phylogenetically separated from other anthocyanin acyltransferases." Plant J 38(6);994-1003. PMID: 15165190
Yamazaki99: Yamazaki M, Gong Z, Fukuchi-Mizutani M, Fukui Y, Tanaka Y, Kusumi T, Saito K (1999). "Molecular cloning and biochemical characterization of a novel anthocyanin 5-O-glucosyltransferase by mRNA differential display for plant forms regarding anthocyanin." J Biol Chem 274(11);7405-11. PMID: 10066805
YonekuraSakakib00: Yonekura-Sakakibara K, Tanaka Y, Fukuchi-Mizutani M, Fujiwara H, Fukui Y, Ashikari T, Murakami Y, Yamaguchi M, Kusumi T (2000). "Molecular and biochemical characterization of a novel hydroxycinnamoyl-CoA: anthocyanin 3-O-glucoside-6"-O-acyltransferase from Perilla frutescens." Plant Cell Physiol 41(4);495-502. PMID: 10845463
Matsuba10: Matsuba Y, Sasaki N, Tera M, Okamura M, Abe Y, Okamoto E, Nakamura H, Funabashi H, Takatsu M, Saito M, Matsuoka H, Nagasawa K, Ozeki Y (2010). "A novel glucosylation reaction on anthocyanins catalyzed by acyl-glucose-dependent glucosyltransferase in the petals of carnation and delphinium." Plant Cell 22(10);3374-89. PMID: 20971893
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
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