Synthesis of Cellulose Precursors. The Involvement of Lipid-Linked Sugars

Particulate preparations from the Chlorophyta Prototheca zopfi catalyze the incorporation of [14C]glucose from UDP-[14C]glucoe into lipids. These lipids have been characterized as lipid-P-glucose, lipid-PP-glucose, and lipid-PP-oligosaccharides. The lipid-linked oligosaccharides were a mixture ranging from a disaccharide to approximately a decasaccharide. Cellulase digestion and periodate oxidation showed that the oligosaccharides seem to be built of beta-1,4-linked glucoses. The lipid moiety had the properties of dolichol. The glucolipids described appeared as precursors of a water-soluble polymer. Treatments of this polymer with hydrolytic enzymes and periodate oxidation that it could be a glycoprotein containing beta-1,4-linked glucoses. When GDP-glucose was added to the incubation mixture, the 14C-labelled soluble polymer became insoluble in hot alkali. This insoluble polymer had the properties expected for cellulose. A scheme is proposed with the reactions involved in the initiation of cellulose biosynthesis.