ent-Sandaracopimaradiene is a precursor of the rice oryzalexins A-F. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. As a minor product, this enzyme also forms ent-pimara-8(14),15-diene, which is the sole product of EC 4.2.3.30, ent-pimara-8(14),15-diene synthase. ent-Pimara-8(14),15-diene is not a precursor in the biosynthesis of either gibberellins or phytoalexins .
ent-Sandaracopimaradiene is a precursor of the rice oryzalexins A-F. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. As a minor product, this enzyme also forms ent-pimara-8(14),15-diene, which is the sole product of EC 4.2.3.30, ent-pimara-8(14),15-diene synthase. ent-Pimara-8(14),15-diene is not a precursor in the biosynthesis of either gibberellins or phytoalexins [2].
LC-MS/MS analyses show that oryzalexins A and C are not detected in either accession W0106 or W1943. Oryzalexins E and F, which are not detected in the two Or accessions, are also undetectable in Oryza sativa cv. Nipponbare. OrKSL10 and OrKSL10ind cannot usually produce ent-sandaracopimaradiene strongly suggesting that no accumulation of oryzalexins A-F is possible in either of the two Or accessions
plants have extensively diversified their arsenal of labdane-related diterpenoids (LRDs), in part via gene duplication and neo-functionalization of the ancestral ent-kaurene synthase (KS) required for gibberellin metabolism. Ricinus communis contains 4 RcKSL isozymes, molecular phylogenetic analysis indicates that RcKS(L)1 is significantly more closely related to dicotyl ent-kaurene synthases (KSs), while the other three, RcKSL2-4, cluster separately. RcKSL2-4 are in close proximity to each other, within a region of 65 kb, with RcKSL2 and 4 occurring as a tandem gene pair. RcKS(L)1 is the only isozyme to react with ent-CPP producing small amounts of ent-kaurene, and is referred to as RcKS1. Both RcKSL2 and RcKSL3 also are selectively reacting with ent-CPP with RcKSL2 producing primarily ent-trachylobane (70%) as well as smaller amounts of ent-kaurene (30%), and RcKSL3 producing ent-sandaracopimaradiene (94%) (EC 4.2.3.29) along with small amounts of ent-labdatriene (3%) and ent-pimaradiene (3%). RcKSL4 seems to be inactive, with no products evident from any substrate, but upon synthesis of a codon-optimized gene for the corrected aa sequence and functional analysis, RcKSL4 selectively reacts with ent-CPP and produces largely ent-beyerene (95%) along with very small amounts of ent-atiserene (4%) and ent-kaurene (1%). The enzymes belong to the terpene synthase family and is a class I diterpene synthase
OsKSL10 encodes ent-sandaracopimaradiene synthase responsible for the biosynthesis of oryzalexins A-F, but oryzalexins E and F are undetectable in Oryza sativa cv. Nipponbare, they are also undetectable in Oryza rufipogon accessions W106 and W1943
site-directed mutagenesis of isozyme RcKSL3, mutation of the residue results in 2fold decrease of the amount of ent-sandaracopimaradiene compared to the wild-type enzyme
molecular phylogenetic analysis and tree, sequence comparisons, overview. The predicted RcKSL3 encodes an active enzyme, isozyme determination and phylogenetic analysis and tree, sequence comparisons, the synthetic RcKS(L) isozyme is truncated to remove the N-terminal plastid-directing transit peptide sequences, it is individually subcloned into compatible expression vectors and coexpressed with either the geranylgeranyl phosphate synthase (GGPS), or the GGPS along with a CPS (EC 5.5.1.13) for recombinant expression in Escherichia coli
Evident and latent plasticity across the rice diterpene synthase family with potential implications for the evolution of diterpenoid metabolism in the cereals
4.2.3.29 ent-sandaracopimaradiene synthase
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