Existence of Branched Side Chains in the Cell Wall Mannan of Pathogenic Yeast, Candida albicans

Abstract

Isolation of side chain oligosaccharides from mannans of Candida albicans NIH B-792 (serotype B) and Candida parapsilosis IFO 1396 strains has been conducted by acetolysis under mild conditions. Structural study of these oligosaccharides by 1H and 13C NMR and methylation analyses indicated the presence of novel branched side chains with the following structures in C. albicans mannan. [sequence: see text] It was observed that the H-1 proton chemical shifts of the second and the third mannose units from the reducing terminus in each oligosaccharide are shifted upfield by substitution with an alpha-linked mannose unit at position 6 of the 3-O-substituted mannose unit. An agglutination inhibition assay between factor 4 serum and cells of Candida stellatoidea IFO 1397 lacking the beta-1,2-linked mannose unit, with oligosaccharides obtained from these mannans, indicated that only the branched oligosaccharides were active. This finding suggests that the branched oligosaccharides correspond to the epitope of antigenic factor 4. The presence of the branched structure in other mannans was detected by the characteristic H-1-H-2-correlated cross-peak of the alpha-1,2-linked mannose unit connected with the 3,6-di-O-substituted one by two-dimensional homonuclear Hartmann-Hahn spectroscopy.

The Components of the Saccharomyces cerevisiaeMannosyltransferase Complex M-Pol I Have Distinct Functions in Mannan Synthesis

“…These organisms contain mannan-like cell wall glycans, although the side branches are highly variable between species, and for Candida it has been shown that an Mnn9p homologue is involved in mannan synthesis (55)(56)(57)(58). Although Mnn9p-containing protein complexes in these species have not so far been reported, it seems likely that the mechanisms that determine which proteins receive mannan in S. cerevisiae will be conserved in other yeasts and fungi.…”

Characterization of a haemolytic factor from Candida albicans

“…The anomeric proton chemical shifts of oligosaccharides were assigned by adapting the findings of Shibata et al (1993Shibata et al ( , 1995 …”

“…C. albicans is a dimorphic fungus which can alternate between yeast and hyphal phases, depending on the growth conditions (Blasi et al, 1994). The cell wall of C. albicans contains a mannan which has a linear 1,6-a-linked mannose backbone with side chains of 1,2-a-, 1,2-p-and 1J-a-linked mannose units (Shibata et al, 1995). The antigenicity of Candida species depends on the structure of their mannans, and differences of antigenicity in mannans are used in the classification of Candida species (Ataoglu et al, 1993;Kobayashi et al, 1992).…”

Characterization of β-1,2-Mannosyltransferase in Candida guilliermondii and Its Utilization in the Synthesis of Novel Oligosaccharides

“…This nonempirical assignment method has been demonstrated to give satisfactory results (8,18,24,25,31). The H-1 signal of the reducing terminal ␣-mannose unit (␦ ϭ ϳ5.35 ppm) was able to be empirically assigned.…”

“…1 based on the results obtained by the structural analysis of C. guilliermondii mannan (18) and the substrate specificity of an ␣-1,6-mannosyltransferase of C. albicans (23) responsible for the formation of the branched oligosaccharides corresponding to factor 4 (24,25). Namely, the introduction of a ␤-1,2-linked mannose unit from GDP-mannose to the nonreducing terminal ␣-1,3-linked mannose unit of an ␣-linked mannopentaosyl side chain, Man␣133(Man␣136)Man␣132Man␣132Man, synthesized from Man␣133Man␣132Man␣132Man corresponding to factor 34 (26), takes place by participation of the ␤-1,2-mannosyltransferase IV, and then, the elongation of a ␤-1,2-linked one to a resulting product, Man␤132Man␣133-(Man␣136)Man␣132Man␣132Man, takes place by participation of the ␤-1,2-mannosyltransferase V in succession.…”