Characterization of Sphingolipids from Mycopathogens:  Factors Correlating with Expression of 2-Hydroxy Fatty Acyl (E)-Δ³-Unsaturation in Cerebrosides of Paracoccidioides brasiliensis and Aspergillus fumigatus

Abstract

Significant differences exist between mammals and fungi with respect to glycosphingolipid (GSL) structure and biosynthesis. Thus, these compounds, as well as the cellular machinery regulating their expression, have considerable potential as targets for the diagnosis and treatment of fungal diseases. In this study, the major neutral GSL components extracted from both yeast and mycelium forms of the thermally dimorphic mycopathogen Paracoccidioides brasiliensis were purified and characterized by 1H and 13C NMR spectroscopy, ESI-MS and ESI-MS/CID-MS, and GC-MS. The major GSLs of both forms were identified as beta-glucopyranosylceramides (GlcCer) having (4E, 8E)-9-methyl-4,8-sphingadienine as long chain base in combination with either N-2'-hydroxyoctadecanoate or N-2'-hydroxy-(E)-3'-octadecenoate. The mycelium form GlcCer had both fatty acids in a approximately 1:1 ratio, while that of the yeast form had on average only approximately 15% of the (E)-Delta 3-unsaturated fatty acid. Cerebrosides from two strains of Aspergillus fumigatus (237 and ATCC 9197) expressing both GalCer and GlcCer were also purified and characterized by similar methods. The GalCer fractions were found to have approximately 70% and approximately 90% N-2'-hydroxy-(E)-3'-octadecenoate, respectively, in the two strains. In contrast, the GlcCer fractions had N-2'-hydroxy-(E)-3'-octadecenoate at only approximately 20 and approximately 50%, respectively. The remainder in all cases was the saturated 2-OH fatty acid, which has not been previously reported in cerebrosides from A. fumigatus. The availability of detailed structures of both glycosylinositol phosphorylceramides [Levery, S. B., Toledo, M. S., Straus, A. H., and Takahashi, H. K. (1998) Biochemistry 37, 8764-8775] and cerebrosides from P. brasiliensis revealed parallel quantitative differences in expression between yeast and mycelium forms, as well as a striking general partitioning of ceramide structure between the two classes of GSLs. These results are discussed with respect to possible functional roles for fungal sphingolipids, particularly as they relate to the morphological transitions exhibited by P. brasiliensis.

Aldose Reductase Inhibitors from the Fruiting Bodies of Ganoderma applanatum

“…They were identified as D-mannitol (1), 7) 2-methoxyfatty acids (2), 8,9) cerebrosides (3), [10][11][12][13] daucosterol (4), 14) 2,5-dihydroxyacetophenone (5), 15) 2,5-dihydroxybenzoic acid (6) 16) and protocatechualdehyde (7) 17,18) by spectral analysis and comparison of their spectroscopic data with those reported. All of these compounds were isolated for the first time from the fruiting bodies of G. applanatum.…”

Identification of Fungal Sphingolipid C9-methyltransferases by Phylogenetic Profiling

“…Radioactivity was detected by radioscanning with a BAS-1000 BioImaging Analyzer (Fujifilm). The 14 C-labeled ceramide spots were scraped off the TLC plate and hydrolyzed with Ba(OH) 2 . The free sphingoid bases were converted to their DNP derivatives and analyzed by reverse-phase HPLC as described above.…”

“…In the case of GIPC, 2 an inositol residue is phosphodiester-linked to the hydrophobic part of the molecule, the ceramide backbone. In the case of cerebrosides, the ceramide is directly linked to a glucosyl or galactosyl residue that can form the base for further glycosylations.…”

“…Different patterns of functional groups are characteristic for GIPC versus cerebrosides as well as for different organisms (see Fig. 1) (1)(2)(3)(4)(5). The functional significance of these differences has yet to be investigated.…”

Nonribosomal cyclic peptides: specific markers of fungal infections

“…38 This approach, however, suffers from a low specificity and the fact that elevated D/L-arabinitol ratios could be measured only in the late phase of infections. 39 In addition to saccharide molecules, attempts to use phytosterols 40 or sphingolipids 41 for fungus characterization have also been made. Unfortunately, none has found a general use.…”