Biosynthesis of the labdane diterpene marrubiin in Marrubium vulgare via a non-mevalonate pathway.
The biosynthesis of the furanic labdane diterpene marrubiin has been studied in plantlets and shoot cultures of Marrubium vulgare (Lamiaceae). The use of [2-14C]acetate, [2-14C]pyruvate, [2-14C]mevalonic acid and [U-14C]glucose incorporation experiments showed that the labelling of sterols in etiolated shoot cultures of M. vulgare was in accordance with their biosynthesis via the acetate-mevalonate pathway. In contrast, the incorporation rates of these precursors into the diterpene marrubiin could not be explained by biosynthesis of this compound via the acetate-mevalonate pathway. Cultivation of etiolated shoot cultures of M. vulgare on medium containing [1-13C]glucose and subsequent 13C-NMR spectroscopy of marrubiin led to the conclusion that the biosynthesis of marrubiin follows a non-mevalonate pathway. All isoprenic units of 13C-labelled marrubiin were enriched in those carbons that correspond to positions 1 and 5 of a putative precursor isopentenyl diphosphate. This labelling pattern from [1-13C]glucose is consistent with an alternative pathway via trioses, which has already been shown to occur in Eubacteria and Gymnospermae. The labdane skeleton is a precursor of many other skeletal types of diterpenes. Therefore it becomes obvious that in connection with the few known examples of a non-mevalonate pathway to isoprenoids the formation of some isoprenoids in plants via a non-mevalonate pathway might be quite common.
Knöss
W
W
Institute of Pharmaceutical Biology, University of Bonn, Federal Republic of Germany.
Reuter
B
B
Zapp
J
J
D000085:Acetates / Q000378:metabolism; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D004224:Diterpenes / Q000737:chemistry / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008798:Mevalonic Acid / Q000378:metabolism*; D018520:Plant Shoots / Q000166:cytology / Q000378:metabolism; D010946:Plants, Medicinal / Q000166:cytology / Q000378:metabolism*; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D013729:Terpenes / Q000378:metabolism; D014197:Trees / Q000378:metabolism
D000085:Acetates; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D004224:Diterpenes; D011106:Polyisoprenyl Phosphates; D011773:Pyruvates; D013729:Terpenes; C105731:marrubiin; D005947:Glucose; C002963:geranylgeranyl pyrophosphate; D008798:Mevalonic Acid