J Biol Chem, Vol. 274, Issue 51, 36312-36320, December 17, 1999

Biosynthesis of a Neo-epi-verrucosane Diterpene in the Liverwort Fossombronia alaskana
A RETROBIOSYNTHETIC NMR STUDY^*

Wolfgang Eisenreich^§, Christoph Rieder, Carola Grammes^¶, Gerhard Heßler, Klaus-Peter Adam^¶, Hans Becker^¶, Duilio Arigoni, and Adelbert Bacher

From the  Institut für Organische Chemie und Biochemie, Technische Universität München, D-85747 Garching, Germany, ^¶ Pharmakognosie und Analytische Phytochemie der Universität des Saarlandes, D-66041 Saarbrücken, Germany, and  Laboratorium für Organische Chemie, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland

The biosynthesis of the diterpene 8-acetoxy-13-hydroxy-5-oxo-13-epi-neoverrucosane in the arctic liverwort Fossombronia alaskana was studied by incorporation experiments using [1-¹³C]- and [U-¹³C₆]glucose as precursors. The ¹³C-labeling patterns of acetyl-CoA, pyruvate, and phosphoenolpyruvate in intermediary metabolism were reconstructed from the ¹³C NMR data of biosynthetic amino acids (leucine, alanine, phenylalanine) and were used to predict hypothetical labeling patterns for isopentenyl pyrophosphate formed via the mevalonate pathway and the deoxyxylulose pathway. The labeling patterns observed for the neoverrucosane diterpene were consistent with the intermediate formation of geranyllinaloyl pyrophosphate assembled from dimethylallyl pyrophosphate and three molecules of isopentenyl pyrophosphate generated predominantly or entirely via 1-deoxyxylulose 5-phosphate. The experimental data can be integrated into a detailed biosynthetic scheme involving a 1,5-hydride shift. The postulated involvement of the 1,5-hydride shift was confirmed by an incorporation experiment with [6,6-²H₂]glucose.