1-deoxy-2-pentulose and isopentenyl-pyrophosphate

Recently, a mevalonate-independent pathway was discovered in bacteria and plants that leads to the formation of isopentenyl diphosphate and dimethylallyl diphosphate, the two basic precursors of isoprenoids. Although many details of the widely distributed pathway are unknown, some intermediates, mechanisms, enzymes and genes of this novel route have been identified. Information on this pathway could provide the basis for the development of new antibiotics, herbicides and antimalarials.

Topics: Diphosphates; Enzymes; Genes, Bacterial; Genes, Plant; Hemiterpenes; Mevalonic Acid; Organophosphorus Compounds; Terpenes; Xylulose

Feeding tobacco BY-2 cells with [2-(13)C,4-(2)H]deoxyxylulose revealed from the (13)C labeling that the plastid isoprenoids, synthesized via the MEP pathway, are essentially derived from the labeled precursor. The ca. 15% (2)H retention observed in all isoprene units corresponds to the isopentenyl diphosphate (IPP)/dimethylallyl diphosphate (DMAPP) ratio (85:15) directly produced by the hydroxymethylbutenyl diphosphate reductase, the last enzyme of the MEP pathway. (2)H retention characterizes the isoprene units derived from the DMAPP branch, whereas (2)H loss represents the signature of the IPP branch. Taking into account the enantioselectivity of the reactions catalyzed by the (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase, the IPP isomerase and the trans-prenyl transferase, a single biogenetic scheme allows to interpret all labeling patterns observed in bacteria or plants upon incubation with (2)H labeled deoxyxylulose.

Topics: Cell Culture Techniques; Cells, Cultured; Erythritol; Hemiterpenes; Nicotiana; Organophosphorus Compounds; Plastids; Sugar Phosphates; Terpenes; Xylulose

Upon feeding of [2-(13)C,4-(2)H]-1-deoxy-D-xylulose to Streptomyces ghanaensis, the deuterium label was retained exclusively at positions C-7 and C-17 in the moenocinol part of the moenomycin antibiotics. This result vindicates the hypothesis that the C(25) structure of moenocinol is assembled from a C(10) and a C(15) precursor, each of which requires for its formation the involvement of a dimethylallyl diphosphate starter unit.

Topics: Anti-Bacterial Agents; Hemiterpenes; Magnetic Resonance Spectroscopy; Molecular Structure; Oligosaccharides; Organophosphorus Compounds; Streptomyces; Terpenes; Xylulose

The biosynthesis of the C5 building block of isoprenoids, isopentenyl diphosphate (IPP), proceeds in higher plants via two basically different pathways; in the cytosolic compartment sterols are formed via mevalonate (MVA), whereas in the plastids the isoprenoids are formed via the 1-deoxyxylulose 5-phosphate/2-C-methylerythritol 4-phosphate pathway (DOXP/MEP pathway). In the present investigation, we found for the Charophyceae, being close relatives to land plants, and in the original green flagellate Mesostignma virilde the same IPP biosynthesis pattern as in higher plants: sterols are formed via MVA, and the phytol-moiety of chlorophylls via the DOXP/MEP pathway. In contrast, representatives of four classes of the Chlorophyta (Chlorophyceae, Ulvophyceae, Trebouxiophyceae, Prasinophyceae) did not incorporate MVA into sterols or phytol. Instead, they incorporated [1-2H1]-1-deoxy-D-xylulose into phytol and sterols. The results indicate that the entire Chlorophyta lineage, which is well separated from the land plant/Charophyceae lineage, is devoid of the acetate/ MVA pathway and uses the DOXP/MEP pathway not only for plastidic, but also for cytosolic isoprenoid formation.

Topics: Carbon Radioisotopes; Chlorophyta; Deuterium; Erythritol; Hemiterpenes; Mevalonic Acid; Organophosphorus Compounds; Pentosephosphates; Phytol; Polyisoprenyl Phosphates; Sterols; Sugar Phosphates; Xylulose

The volatile hemiterpene 2-methyl-3-buten-2-ol (MBO) is emitted from the needles of several pine species from the Western United States and contributes to ozone formation in the atmosphere. It is synthesised enzymatically from dimethylallyl diphosphate (DMAPP). We show here that needles of Pinus ponderosa Laws. incorporated [1-2H1]-1-deoxy-D-xylulose (d-DOX) into the emitted MBO, but not D,L-[2-13C]mevalonic acid lactone. Furthermore, MBO emission was inhibited by fosmidomycin, a specific inhibitor of the second enzyme of the mevalonate-independent pathway of isopentenyl diphosphate and DMAPP formation, i.e. the 1-deoxy-D-xylulose 5-phosphate/2-C-methyl-D-erythritol 4-phosphate (DOXP/MEP) pathway. We thus prove that MBO emitted from needles of P. ponderosa is primarily formed via the DOXP/MEP pathway.

Topics: Hemiterpenes; Mevalonic Acid; Organophosphorus Compounds; Pentanols; Pinus; Pinus ponderosa; Terpenes; Xylulose

In further substantiating the novel mevalonate-independent pathway for isoprenoid biosynthesis, which generates isopentenyl diphosphate (IPP) via 1-deoxy-D-xylulose-5-phosphate, labeling experiments with 1-[2H(1)]deoxy-D-xylulose were performed with various higher plants and algae: efficient incorporation was observed into isoprene emitted by Populus, Chelidonium, and Salix, into the phytol moiety of chlorophylls in a red alga (Cyanidium), in two green algae (Scenedesmus, Chlamydomonas), and a higher plant (Lemna). By contrast, 13C-mevalonate applied was incorporated into isoprene and phytol to a much lower extent or not at all. This demonstrates that this '1-deoxy-D-xylulose-5-phosphate pathway' for biosynthesis of plastidic isoprenoids is widely distributed in photosynthetic organisms.

Topics: Butadienes; Carbon Isotopes; Chlorophyta; Deuterium; Eukaryota; Glycosides; Hemiterpenes; Magnetic Resonance Spectroscopy; Magnoliopsida; Mevalonic Acid; Molecular Structure; Organophosphorus Compounds; Pentanes; Phytol; Rhodophyta; Sterols; Xylulose