Evident and latent plasticity across the rice diterpene synthase family with potential implications for the evolution of diterpenoid metabolism in the cereals

Abstract

SYNOPSIS The evolution of natural products biosynthetic pathways can be envisioned to occur via a number of mechanisms. Here we provide evidence that latent plasticity plays a role in such metabolic evolution. In particular, rice (Oryza sativa) produces both ent- and syn-copalyl diphosphate (CPP), which are substrates for downstream diterpene synthases. Here we report that several members of this enzymatic family exhibit dual reactivity with some pairing of ent-, syn-, or normal CPP stereochemistry. Evident plasticity was observed, as a previously reported ent-sandaracopimaradiene synthase also converts syn-CPP to syn-labda-8(17),12E,14-triene, which can be found in planta. Notably, normal CPP is not naturally found in rice. Thus, the presence of diterpene synthases that react with this non-native metabolite reveals latent enzymatic/metabolic plasticity, providing biochemical capacity for utilization of such a novel substrate (i.e., normal CPP) that may arise during evolution, the implications of which are discussed.

CYP701A8: A Rice ent-Kaurene Oxidase Paralog Diverted to More Specialized Diterpenoid Metabolism

“…These results are consistent with both the availability of the precursor diterpenes (i.e. ent-kaurene is produced at much lower levels under these conditions; Morrone et al, 2011), and the expression pattern of OsKOL4 (Fig. 5), indicating a causative relationship.…”

“…Transcription of the genes encoding the relevant diterpene synthases, as well as production of the diterpene precursors themselves, is inducible by methyl jasmonate Morrone et al, 2011). Thus, we investigated the effect of such induction on transcription of OsKOL4 and accumulation of its enzymatic products.…”

Manoyl Oxide (13R), the Biosynthetic Precursor of Forskolin, Is Synthesized in Specialized Root Cork Cells in Coleus forskohlii

“…One clade includes the EKS of general metabolism of gibberellic acid formation together with a set of rice (Oryza sativa) class I diTPS that evolved through species-specific duplications associated with neofunctionalization in rice-specialized metabolism (Morrone et al, 2011). CfTPS14 falls into this clade.…”

Discovery, Biosynthesis and Stress-Related Accumulation of Dolabradiene-Derived Defenses in Maize

“…All of these enzymes have either validated or predicted roles in GA metabolism. However, the frequently observed substrate promiscuity of characterized enzymes (Peters, 2010;Morrone et al, 2011;Zerbe and Bohlmann, 2015) also may enable roles in defense-related specialized metabolism. In the absence of mutant analyses, the maize kauralexin and zealexin metabolic pathways have remained largely unproven, with the exception of the ent-CPP synthase ZmAN2, which has been empirically demonstrated to function in kauralexin formation (Harris et al, 2005;Vaughan et al, 2015).…”