CHARACTERIZATION OF BETA-1,2-MANNOSYLTRANSFERASE IN CANDIDA-GUILLIERMONDII AND ITS UTILIZATION IN THE SYNTHESIS OF NOVEL OLIGOSACCHARIDES

A particulate insoluble enzyme fraction containing mannosyltransferase s from Candida guilliermondii IFO 10279 strain cells was obtained as t he residue after extracting a 105,000 x g pellet of cell homogenate wi th 1% Triton X-100. Incubation of this fraction with a mannopentaose, Man alpha 1-->3(Man alpha 1-->6)Man alpha 1-->2Man alpha 1-->2Man, in the presence of GDP-mannose and Mn2+ ion at pH 6.0 save a third type o f beta-1,2 linkage-containing mannohexaose, Man beta 1-->2Man alpha 1- ->3(Man alpha 1-->6)Man alpha 1-->2Man alpha 1-->2Man, the structure o f which was identified by means of a sequential NMR assignment. The re sults of a substrate specificity study indicated that the beta-1,2-man nosyltransferase requires a mannobiosyl unit, Man alpha 1-->3Man alpha 1-->, at the nonreducing terminal site. We synthesized novel oligosac charides using substrates possessing a nonreducing terminal alpha-1,3- linked mannose unit prepared from various yeast mannans. Further incub ation of the enzymatically synthesized oligosaccaride with the enzyme fraction gave the following structure, Man beta 1-->2Man beta 1-->2Man alpha 1-->3(Man alpha 1-->6)Man alpha 1-->2Man alpha 1-->2Man, which has been found to correspond to antigenic factor 9. Incubation of Cand ida albicans serotype B mannan with the enzyme fraction gave significa ntly transformed mannan, which contains the third type of beta-1,2-lin ked mannose units.