Sphingolipids of the mycopathogen Sporothrix schenckii: identification of a glycosylinositol phosphorylceramide with novel core GlcNH(2)alpha1-->2Ins motif

Acidic glycosphingolipid components were extracted from the yeast form of the dimorphic mycopathogen Sporothrix schenckii. Two minor and the major fraction from the yeast form (Ss-Y1, -Y2, and -Y6, respectively) have been isolated. By a combination of 1- and 2-D 1H-nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and gas chromatography/mass spectrometry (GC/MS), Ss-Y6 was determined to be triglycosylinositol phosphorylceramide with a novel glycan structure, Manalpha1-->3Manalpha1-->6GlcNH(2)alpha1-->2Ins1-P-1Cer (where Ins=myo-inositol, P=phosphodiester). While the GlcNH(2)alpha1-->6Ins1-P- motif is found widely distributed in eukaryotic GPI anchors, the linkage GlcNH(2)alpha1-->2Ins1-P- has not been previously observed in any glycolipid. Ss-Y1 and Ss-Y2 were both found to have the known glycan structure Manalpha1-->3Manalpha1-->2Ins1-P-1Cer. Together with the results of a prior study Toledo et al. (2001) Biochem. Biophys. Res. Commun. 280, 19-24] which showed that the mycelium form expresses GIPCs with the structures Manalpha1-->6Ins1-P-1Cer and Manalpha1-->3Manalpha1-->6Ins1-P-1Cer, these results demonstrate that S. schenckii can synthesize glycosylinositol phosphorylceramides with at least three different core linkages.