The pathogenic yeast Candida albicanshas the ability to synthesize unique sequences of β-1,2-oligomannosides that act as adhesins, induce cytokine production, and generate protective antibodies. Depending on the growth conditions, β-1,2-oligomannosides are associated with different carrier molecules in the cell wall. Structural evidence has been obtained for the presence of these residues in the polysaccharide moiety of the glycolipid, phospholipomannan (PLM). In this study, the refinement of purification techniques led to large quantities of PLM being extracted from Candida albicans cells. A combination of methanolysis, gas chromatography, mass spectrometry, and nuclear magnetic resonance analyses allowed the complete structure of PLM to be deduced. The lipid moiety was shown to consist of a phytoceramide associating a C18/C20 phytosphingosine and C25, C26, or mainly C24 hydroxy fatty acids. The spacer linking the glycan part was identified as a unique structure: -Man-P-Man-Ins-P-. Therefore, in contrast to the major class of membranous glycosphingolipids represented by mannose diinositol phosphoceramide, which is derived from mannose inositol phosphoceramide by the addition of inositol phosphate, PLM seems to be derived from mannose inositol phosphoceramide by the addition of mannose phosphate. In relation to a previous study of the glycan part of the molecule, the assignment of the second phosphorus position leads to the definition of PLM β-1,2-oligomannosides as unbranched linear structures that may reach up to 19 residues in length. Therefore, PLM appears to be a new type of glycosphingolipid, which is glycosylated extensively through a unique spacer. The conferred hydrophilic properties allow PLM to diffuse into the cell wall in which together with mannan it presents C. albicansβ-1,2-oligomannosides to host cells.

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
1,0,2,6,0,2,2,2	bDManp	102.6	78.52-81.34	73.55-73.9	69.24-69.62	78.22-78.6	62.57-62.99
1,0,2,6,0,2,2,2,2	bDManp	102.6	71.2	75.01	68.86	78.24	63.13
1,0,2,6,0,2,2	bDManp	102.44	80.99	73.55	69.5	78.6	62.77
1,0,2,6,0,2	bDManp	100.22	81.99	73.5	69.4	78.2	62.57
1,0,2,6,0	aDManp	95.38	79.77	70.63	69.4	75.47	62.57
1,0,2,6	P
1,0,2	aDManp	102.39	71.85	71.86	67.98	73.67	65.85
1,0	INO	76.85	79.77	72.2	73.64	76.81	73.64
1	P
	CER


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
1,0,2,6,0,2,2,2	bDManp	4.75	4.127	3.351	3.3	3.20	3.50-3.72
1,0,2,6,0,2,2,2,2	bDManp	4.751	3.781	3.288	3.368	3.22	3.50-3.72
1,0,2,6,0,2,2	bDManp	4.683	4.16	3.391	3.231	3.124	3.50-3.72
1,0,2,6,0,2	bDManp	4.692	3.976	3.42	3.25	3.167	3.50-3.72
1,0,2,6,0	aDManp	5.43	4.026	3.647	3.37	3.535	3.53-3.65
1,0,2,6	P
1,0,2	aDManp	4.999	3.712	3.54	3.53	3.937	3.88
1,0	INO	3.757	4.045	3.202	3.378	2.975	3.502
1	P
	CER


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
1,0,2,6,0,2,2,2	bDManp	102.6/4.75	78.52-81.34/4.127	73.55-73.9/3.351	69.24-69.62/3.3	78.22-78.6/3.20	62.57-62.99/3.50-3.72
1,0,2,6,0,2,2,2,2	bDManp	102.6/4.751	71.2/3.781	75.01/3.288	68.86/3.368	78.24/3.22	63.13/3.50-3.72
1,0,2,6,0,2,2	bDManp	102.44/4.683	80.99/4.16	73.55/3.391	69.5/3.231	78.6/3.124	62.77/3.50-3.72
1,0,2,6,0,2	bDManp	100.22/4.692	81.99/3.976	73.5/3.42	69.4/3.25	78.2/3.167	62.57/3.50-3.72
1,0,2,6,0	aDManp	95.38/5.43	79.77/4.026	70.63/3.647	69.4/3.37	75.47/3.535	62.57/3.53-3.65
1,0,2,6	P
1,0,2	aDManp	102.39/4.999	71.85/3.712	71.86/3.54	67.98/3.53	73.67/3.937	65.85/3.88
1,0	INO	76.85/3.757	79.77/4.045	72.2/3.202	73.64/3.378	76.81/2.975	73.64/3.502
1	P
	CER

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

R1 = CER
R2 = INO
Warning = sub-repeat ending at bDManp: unknown unit count was assumed to be 3
[1*]OP(=O)(O)O[2*]O[C@H]1O[C@H](COP(=O)(O)O[C@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O)[C@@H](O)[C@H](O)[C@@H]1O

1490.092 g/mol (C₄₈H₈₃R₂O₄₈P₂, R = residue superclass(es), not counted in mol weight)