Glycosyltransferases are specific enzymes that catalyse the transfer of monosaccharide moieties to biological substrates, including proteins, lipids and carbohydrates. These enzymes are present from prokaryotes to humans, and their glycoconjugate products are often vital for survival of the organism. Many glycosyltransferases found in fungal pathogens such as Cryptococcus neoformans do not exist in mammalian systems, making them attractive potential targets for selectively toxic agents. In this article, we present the features of this diverse class of enzymes, and review the fungal glycosyltransferases that are involved in synthesis of the cell wall, the cryptococcal capsule, glycoproteins and glycolipids. We specifically focus on enzymes that have been identified or studied in C. neoformans, and we consider future directions for research on glycosyltransferases in the context of this opportunistic pathogen.

polysaccharide, glycan, glycosyltransferase, glycosylation, fungi, Cryptococcus

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*OC[C@H]1O[C@H](OC[C@H]2O[C@H](OC[C@H]3O[C@H](OC[C@H]4O[C@H](*)[C@H](O)[C@@H](O[C@@H]5O[C@H](CO)[C@H](O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O)[C@@H]6O)[C@H](O)[C@H]5O)[C@H]4O)[C@H](O)[C@@H](O)[C@H]3O)[C@H](O)[C@@H](O[C@@H]3O[C@H](CO)[C@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O[C@@H]6OC[C@@H](O)[C@H](O)[C@H]6O)[C@@H]5O)[C@@H]4O[C@@H]4OC[C@@H](O)[C@H](O)[C@H]4O)[C@H](O[C@@H]4OC[C@@H](O)[C@H](O)[C@H]4O)[C@H]3O)[C@H]2O)[C@H](O)[C@@H](O)[C@H]1O

2017.755 g/mol (C₇₅H₁₂₄R₂O₆₂, R = next and previous repeats, not counted in mol weight)

In the study, a new triple-helix polysaccharide with favorable stability was purified from C. cornucopioides. Its structural characterization, stability and solution behavior were investigated by the GC-MS, periodate oxidation-smith degradation, FT-IR, 1D and 2D NMR spectroscopy, methylation analysis, Scanning electron microscope, Congo-red, CD, TGA and DSC analysis. The results showed that Craterellus cornucopioide polysaccharide (CCP) possessed the molecular weight of 1970 kDa, is mainly composed of mannose (48.73%), galactose (17.37%), glucose (15.97%) and xylose (17.93%), respectively. It was a heteroglycan with (1→)-linked-β-D-Manp-(1→6)-linked α-d-Galp backbone distributed by (1→4)-linked-α-D-Xylp-t-α-D-Manp and t-β-D-Glup units at O-6. The result of TGA and DSC assay indicated that CCP has a favorable thermal stability. MTT and Scanning electro microscopy (SEM) assay showed that CCP could significantly improve the proliferation activity and induce cells activation of RAW264.7 in a certain range of concentrations and period.

polysaccharide, chemical structure, stability, immunomodulatory activity, Craterellus cornucopioides

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3	aDGalp	97.30	70.03	69.99	72.29	75.17	66.32
	bDManp	103.66	73.18	78.98	72.79	75.41	69.45
6,4	aDManp	101.22	72.38	68.80	71.59	69.99	62.34
6	aDXylp	102.62	71.14	68.82	77.78	60.99
6	bDGlcp	98.08	74.87	73.42	70.08	72.58	60.90


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3	aDGalp	4.94	3.82	3.99	3.62	3.75	3.90
	bDManp	4.72	3.67	3.66	3.55	3.41	3.83
6,4	aDManp	5.09	3.89	4.15	3.41	3.29	3.56
6	aDXylp	5.03	3.76	4.00	3.91	3.69
6	bDGlcp	4.88	3.78	3.88	3.95	3.67	3.84


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3	aDGalp	97.30/4.94	70.03/3.82	69.99/3.99	72.29/3.62	75.17/3.75	66.32/3.90
	bDManp	103.66/4.72	73.18/3.67	78.98/3.66	72.79/3.55	75.41/3.41	69.45/3.83
6,4	aDManp	101.22/5.09	72.38/3.89	68.80/4.15	71.59/3.41	69.99/3.29	62.34/3.56
6	aDXylp	102.62/5.03	71.14/3.76	68.82/4.00	77.78/3.91	60.99/3.69
6	bDGlcp	98.08/4.88	74.87/3.78	73.42/3.88	70.08/3.95	72.58/3.67	60.90/3.84

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*OC[C@H]1O[C@H](O[C@@H]2[C@H](O)[C@H](*)O[C@H](CO[C@H]3OC[C@@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]4O)[C@H](O)[C@H]3O)[C@H]2O)[C@H](O)[C@@H](O)[C@H]1O

618.538 g/mol (C₂₃H₃₈R₂O₁₉, R = next and previous repeats, not counted in mol weight)