Detection of beta-1,2-mannosyltransferase in Candida albicans cells

A particulate insoluble fraction from Candida albicans J-1012 (serotype A) strain cells was obtained as the residue after extracting a 105,000 x g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Man beta 1-->2Man alpha 1-->(2Man alpha 1-->)(2)2Man (alpha beta Man5), in the presence of GDP-mannose followed by high performance liquid chromatography showed the formation of a mannohexaose. Analysis of the product by 1H NMR indicates that alpha beta Man5 was changed to Man beta 1-->2Man beta 1-->2Man alpha 1-->(2Man alpha 1-->)2 2Man (alpha beta Man6). This beta-1,2-mannosyltransferase (ManTase) II activity was completely inhibited by Zn2+ and was not restored by the addition of EDTA. The corresponding enzyme fraction from C. albicans NIH B-792 (serotype B) strain cells, the mannan of which does not possess both the alpha beta Man5 and alpha beta Man6 side chains, also exhibited the same beta-1,2-ManTase II activity.