1-deoxy-2-pentulose and isoprene

Topics: Butadienes; Erythritol; Euphorbia; Fungi; Glucose; Hemiterpenes; Latex; Metabolic Networks and Pathways; Mevalonic Acid; Phosphates; Phytosterols; Triterpenes; Xylulose

Feeding experiments were independently performed with [1-13C]deoxy-D-xylulose triacetate and (RS)-[2-13C]mevalonolactone in the tobacco plant. The labeling pattern for solanesol was elucidated to reveal that the isoprene moiety of solanesol would be derived from deoxy-xylulose. The result strongly suggests that tobacco solanesol is biosynthesized via the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway.

Topics: Butadienes; Carbon Radioisotopes; Erythritol; Hemiterpenes; Nicotiana; Pentanes; Radioactive Tracers; Sugar Phosphates; Terpenes; Xylulose

A green callus culture of Croton sublyratus Kurz established from the leaf explants appeared to actively synthesize two well-known phytosterols, beta-sitosterol and stigmasterol. The phytosterol biosynthesis was highly active during the linear phase of the culture. Feeding of [1-13C]glucose into the callus culture at this growth phase showed that the label from glucose was highly incorporated into both phytosterols. Isolation of the labeled products followed by 13C NMR analysis revealed that the phytosterols had their 13C-labeling patterns consistent with the acquisition of isoprene units via both the mevalonate pathway and the deoxyxylulose pathway with relatively equal contribution. Since the biosynthesis of phytosterol has so far been reported to be mainly from the classical mevalonate pathway, this study provides a new evidence on the biosynthesis of phytosterols via the novel deoxyxylulose pathway.

Topics: Butadienes; Carbon Isotopes; Chromatography, Thin Layer; Croton; Glucose; Hemiterpenes; Magnetic Resonance Spectroscopy; Mevalonic Acid; Pentanes; Plant Leaves; Sitosterols; Stigmasterol; Time Factors; 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