title: Functional characterization of wheat copalyl diphosphate synthases sheds light on the early evolution of labdane-related diterpenoid metabolism in the cereals.
abstract: Two of the most agriculturally important cereal crop plants are wheat (Triticum aestivum) and rice (Oryza sativa). Rice has been shown to produce a number of diterpenoid natural products as phytoalexins and/or allelochemicals--specifically, labdane-related diterpenoids, whose biosynthesis proceeds via formation of an eponymous labdadienyl/copalyl diphosphate (CPP) intermediate (e.g., the ent-CPP of gibberellin phytohormone biosynthesis). Similar to rice, wheat encodes a number of CPP synthases (CPS), and the three CPS characterized to date (TaCPS1-3) all have been suggested to produce ent-CPP. However, several of the downstream diterpene synthases will only react with CPP intermediate of normal or syn, but not ent, stereochemistry, as described in the accompanying report. Investigation of additional CPS did not resolve this issue, as the only other functional synthase (TaCPS4) also produced ent-CPP. Chiral product characterization of all the TaCPS then established that TaCPS2 uniquely produces normal, rather than ent-, CPP, thus, providing a suitable substrate source for the downstream diterpene synthases. Notably, TaCPS2 is most homologous to the similarly stereochemically differentiated syn-CPP synthase from rice (OsCPS4), while the non-inducible TaCPS3 and TaCPS4 cluster with the rice OsCPS1 required for gibberellin phytohormone biosynthesis, as well as with a barley (Hordeum vulgare) CPS (HvCPS1) that also is characterized here as similarly producing ent-CPP. These results suggest that diversification of labdane-related diterpenoid metabolism beyond the ancestral gibberellins occurred early in cereal evolution, and included the type of stereochemical variation demonstrated here.
authors.affiliation: Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
authors.forename: Yisheng
authors.initials: Y
authors.lastname: Wu
authors.forename: Ke
authors.initials: K
authors.lastname: Zhou
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Toyomasu
authors.forename: Chizu
authors.initials: C
authors.lastname: Sugawara
authors.forename: Madoka
authors.initials: M
authors.lastname: Oku
authors.forename: Shiho
authors.initials: S
authors.lastname: Abe
authors.forename: Masami
authors.initials: M
authors.lastname: Usui
authors.forename: Wataru
authors.initials: W
authors.lastname: Mitsuhashi
authors.forename: Makiko
authors.initials: M
authors.lastname: Chono
authors.forename: Peter M
authors.initials: PM
authors.lastname: Chandler
authors.forename: Reuben J
authors.initials: RJ
authors.lastname: Peters
mesh_terms: D000465:Algorithms; D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D019295:Computational Biology; D004224:Diterpenes / Q000737:chemistry / Q000378:metabolism*; D002523:Edible Grain / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D014908:Triticum / Q000201:enzymology*
chemical_list: D004224:Diterpenes; D010940:Plant Proteins; D011994:Recombinant Proteins; D019883:Alkyl and Aryl Transferases; C090963:ent-kaurene synthetase A