Detection of β-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 × g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Man β1 → 2Man α1 → (2Man α1 →) 22Man (αβMan 5), 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 αβMan 5 was changed to Man β1 → 2Man β1 → 2Man α1 → (2Man α1 →) 22Man (αβMan 6). This β-1,2-mannosyltransferase (ManTase) II activity was completely inhibited by Zn 2+ 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 αβMan 5 and αβMan 6 side chains, also exhibited the same β-1,2-ManTase II activity.