出版社：American Society for Biochemistry and Molecular Biology
摘要：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), Man p (α1→3)Man p (α1→2)Ins-P-Cer (Af-2), Man p (α1→2)Man p (α1→3)Man p (α1→2)Ins-P-Cer (Af-3a), Man p (α1→3)[Gal f (β1→6)]Man p (α1→2)-Ins-P-Cer (Af-3b), Man p (α1→2)-Man p (α1→3)[Gal f (β1→6)]Man p (α1→2)Ins-P-Cer (Af-4), and Man p (α1→3)Man p (α1→6)Glc p N(α1→2)Ins-P-Cer (Af-3c) (where Ins = myo -inositol and P = phosphodiester). A minor A. fumigatus GIPC was also identified as the N -acetylated version of Af-3c (Af-3c*), which suggests that formation of the GlcNα1→2Ins linkage may proceed by a two-step process, similar to the GlcNα1→6Ins linkage in glycosylphosphatidylinositol (GPI) anchors (transfer of GlcNAc, followed by enzymatic de- N -acetylation). The glycosylinositol of Af-3b, which bears a distinctive branching Gal f (β1→6) residue, is identical to that of a GIPC isolated previously from the dimorphic mycopathogen Paracoccidioides brasiliensis (designated Pb-3), but components Af-3a and Af-4 have novel structures. Overlay immunostaining of A. fumigatus GIPCs separated on thin-layer chromatograms was used to assess their reactivity against sera from a patient with aspergillosis and against a murine monoclonal antibody (MEST-1) shown previously to react with the Gal f (β1→6) residue in Pb-3. These results are discussed in relation to pathogenicity and potential approaches to the immunodiagnosis of A. fumigatus .
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