STRUCTURAL STUDY OF A CELL-WALL MANNAN PROTEIN COMPLEX OF THE PATHOGENIC YEAST CANDIDA-GLABRATA IFO-0622 STRAIN

We conducted a structural analysis of the cell wall mannan-protein complex (mannan) isolated from a pathogenic yeast, Candida glabrata IFO 0622 strain. The chemical structure of mannobiose released from this mannan by treatment with 10 mm HCl at 100 °C for 1 h was identified as Manpβ1-2Man. The treatment of this mannan with 100 mm NaOH at 25 °C for 18 h gave a mixture of α-1,2- and α-1,3-linked oligosaccharides, from tetraose to biose, and mannose. The acid- and alkalistable mannan moiety was subjected to mild acetolysis with a 100:100:1 ( v v) mixture of (CH3CO)2O, CH3COOH, and H2SO4 at 40 °C for 36 h. The resultant three novel oligosaccharides, tetraose, hexaose, and heptaose, were identified as Manpβ1-2Manpα1-2Manpα1-2Man, Manpα1-2Manpα1-2 Manpα1-6Manpα1- 2Manpα1-2Man, and Manpα1-3Manpα1-2Manpal-2Manpα-16Manpα1-2Manpα1-2Man, respectively, in addition to the three known oligosaccharides, Manpα1-2Man, Manpα1-2Manpα1-2Man, and Manpα1-3Manpα1-2Manpα1-2Man. A sequential analytical procedure involving partial acid hydrolysis with hot 0.3 m H2SO4, methylation, fast atom bombardment mass, and 1H NMR analyses was quite effective in the structural determination of the novel oligosaccharides. The results indicate that this mannan possesses a structure closely resembling that of Saccharomyces cerevisiae X2180-1A wild type strain, with the presence of small amounts of oligomannosyl residue, Manpβ1-2Manpα1-X, corresponding to one of the epitopes dominating serotype-A specificity of Candida spp., in addition to branches corresponding to hexaose and heptaose each containing one intermediary α-1,6 linkage. © 1992.