title: IeCPS2 is potentially involved in the biosynthesis of pharmacologically active Isodon diterpenoids rather than gibberellin.
abstract: The traditional Chinese medicinal plant, Isodon L., is remarkably rich in pharmacologically active ent-kaurane diterpenoids of diverse carbon skeletons. In an effort to create a resource for gene discovery and elucidate the biosynthesis of Isodonent-kaurane diterpenoids, three cDNAs (named IeCPS1, IeCPS2 and IeCPS2a) were isolated putatively encoding copalyl diphosphate synthases from Isodoneriocalyx leaves. Recombinant proteins of IeCPS1 and IeCPS2 were expressed, respectively, in Escherichia coli, and were shown to specifically convert geranylgeranyl diphosphate to copalyl diphosphate as demonstrated by GC-MS analyses. Based on tissue-specific expression and metabolic localization studies, the IeCPS2 transcripts were detected in young and mature leaves where the dominant ent-kaurane diterpenoid maoecrystal B accumulates, whereas no detectable expression of IeCPS2 was observed in germinating seeds where the gibberellin biosynthetic pathway is usually active. In addition, no evidence for maoecrystal B was found in germinating seeds. On the other hand, IeCPS1 transcripts significantly accumulated in germinating seeds as well as in leaves. The biochemical and molecular genetic evidence thus indicated that IeCPS2 is a copalyl diphosphate synthase potentially involved in the biosynthesis of Isodon diterpenoids in leaves, while IeCPS1 is more probably relevant to gibberellin formation and may, in addition, participate in Isodonent-kaurane diterpenoid production.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.
authors.forename: Jun-Ling
authors.initials: JL
authors.lastname: Li
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Chen
authors.forename: Qiu-Ping
authors.initials: QP
authors.lastname: Jin
authors.forename: Juan
authors.initials: J
authors.lastname: Gao
authors.forename: Pei-Ji
authors.initials: PJ
authors.lastname: Zhao
authors.forename: Shan
authors.initials: S
authors.lastname: Lu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zeng
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D045786:Diterpenes, Kaurane / Q000096:biosynthesis* / Q000737:chemistry; D004789:Enzyme Activation; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry; D018525:Germination; D005875:Gibberellins / Q000737:chemistry*; D037602:Isodon / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics; D008516:Medicine, Chinese Traditional; D008969:Molecular Sequence Data; D010755:Organophosphates / Q000737:chemistry; D010802:Phylogeny; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011106:Polyisoprenyl Phosphates / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012639:Seeds / Q000737:chemistry / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D018076:DNA, Complementary; D045786:Diterpenes, Kaurane; D005875:Gibberellins; D010755:Organophosphates; D010940:Plant Proteins; D011106:Polyisoprenyl Phosphates; D011994:Recombinant Proteins; C408747:copalyl diphosphate; D019883:Alkyl and Aryl Transferases; C090963:ent-kaurene synthetase A; C002963:geranylgeranyl pyrophosphate