A novel xylosylphosphotransferase activity discovered in Cryptococcus neoformans.

Cryptococcus neoformans is a fungal pathogen that causes serious disease in immunocompromised individuals. The organism produces a distinctive polysaccharide capsule that is necessary for its virulence, a predominantly polysaccharide cell wall, and a variety of protein- and lipid-linked glycans. The glycan synthetic pathways of this pathogen are of great interest.

Mammalian cell ganglioside-binding specificities of E. coli enterotoxins LT-IIb and variant LT-IIb(T13I).

LT-IIb, a type II heat-labile enterotoxin of Escherichia coli, is a potent immunologic adjuvant with high affinity binding for ganglioside GD1a. Earlier study suggested that LT-IIb bound preferentially to the terminal sugar sequence NeuAcalpha2-3Galbeta1-3GalNAc. However, studies in our laboratory suggested a less restrictive binding epitope.

Stress-induced cell death is mediated by ceramide synthesis in Neurospora crassa.

The combined stresses of moderate heat shock (45 degrees C) and analog-induced glucose deprivation constitute a lethal stress for Neurospora crassa. We found that this cell death requires fatty acid synthesis and the cofactor biotin. In the absence of the cofactor, the stressed cells are particularly sensitive to exogenous ceramide, which is lethal at low concentrations.

Beta1,2-xylosyltransferase Cxt1p is solely responsible for xylose incorporation into Cryptococcus neoformans glycosphingolipids.

The Manalpha1,3(Xylbeta1,2)Manalpha structural motif is common to both capsular polysaccharides of Cryptococcus neoformans and to cryptococcal glycosphingolipids. Comparative analysis of glycosphingolipid structural profiles in wild-type and mutant strains showed that the Xylbeta1,2-transferase (Cxt1p) that participates in capsular polysaccharide biosynthesis is also the sole transferase responsible for adding xylose to C. neoformans glycosphingolipids.

Analysis of glycosylinositol phosphorylceramides expressed by the opportunistic mycopathogen Aspergillus fumigatus.

Acidic glycosphingolipid components were extracted from the opportunistic mycopathogen Aspergillus fumigatus and identified as inositol phosphorylceramide and glycosylinositol phosphorylceramides (GIPCs). Using nuclear magnetic resonance sppectroscopy, mass spectrometry, and other techniques, the structures of six major components were elucidated as Ins-P-Cer (Af-0), Manp(alpha1-->3)Manp(alpha1-->2)Ins-P-Cer (Af-2), Manp(alpha1-->2)Manp(alpha1-->3)Manp(alpha1-->2)Ins-P-Cer (Af-3a), Manp(alpha1-->3)[Galf(beta1-->6)]Manp(alpha1-->2)-Ins-P-Cer (Af-3b), Manp(alpha1-->2)-Manp(alpha1-->3)[Galf(beta1-->6)]Manp(alpha1-->2)Ins-P-Cer (Af-4), and Manp(alpha1-->3)Manp(alpha1-->6)GlcpN(alpha1-->2)Ins-P-Cer (Af-3c) (where Ins = myo-inositol and P = phosphodiester). A minor A.