Formation of lipid-linked sugars in mycelial and yeast-like forms of Mucor rouxii.

Cell wall fragments from both yeast-like and mycelial forms of the dimorphic fungus Mucor rouxii were used as enzymatic preparations to study the synthesis and role of prenyl-phospho-sugars in these systems. In the presence of GDP [14C] mannose two main products were formed. One of them was characterized as dolichol-monophosphate beta-mannose on the following basis: solubility in organic solvents, behaviour upon paper chromatography, DEAE cellulose column chromatography, mild acid hydrolysis, alkali treatment, catalytic reduction and phenol degradation. The other product was identified as a glycoprotein containing a single mannose unit linked to a serine or threonine residue. It was degraded with pronase and by mild NaOH-NaBH4 treatment all the radioactivity was released as free mannitol. When UDP [14C] glucose was employed as sugar donor two butanol soluble components were isolated. One of them (25%) was characterized as dolichol-monophosphate-beta-glucose on the basis of the same criteria as described above. The other one (75%) was neutral and was not studied in detail. Mycelial enzymes were about 40 times more active in the synthesis of the dolichol derivatives. In addition, large amounts of glycogen were detected. The role that both dolichol derivatives might play in glycoprotein biosynthesis is discussed.