Occurrence of a Uridine Diphosphate Glucose:Sterol Glucosyltransferase in Candida bogoriensis

Crude extracts prepared by sonicating Candida bogoriensis cells catalyzed the incorporation of radioactivity from UDP-[14C]glucose into a lipid different from the hydroxydocosanoic acid glycosides also formed by this organism. 1-Butanol-acetone extraction of lyophilized crude extract made the glycosyltransferase dependent upon added C. bogoriensis lipids. The active lipid acceptor was purified and identified as ergosterol, and both authentic ergosterol and cholesterol were effective in stimulating glucosyltransferase activity. Incubation of the 1-butanol-acetone extract with UDP-[14C]glucose and [1,2-3H]cholesterol yielded a glycolipid product containing equimolar amounts of 14C and 3H. The product was stable to sodium methoxide but was hydrolyzed in methanolic HCl, and therefore has the properties of cholesteryl glucoside. The crude UDP-glucose: sterol glucosyltransferase was stimulated by ethanol in the range of 7 to 15% by volume, and retained activity in up to 20% ethanol.