Toledo M S, Levery S B, Straus A H, Suzuki E, Momany M, Glushka J, Moulton J M, Takahashi H K
Department of Biochemistry, Universidade Federal de São Paulo/Escola Paulista de Medicina, Brasil.
Biochemistry. 1999 Jun 1;38(22):7294-306. doi: 10.1021/bi982898z.
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.
哺乳动物和真菌在糖鞘脂（GSL）结构和生物合成方面存在显著差异。因此，这些化合物以及调节其表达的细胞机制，作为真菌疾病诊断和治疗的靶点具有相当大的潜力。在本研究中，从热双态致病性真菌巴西副球孢子菌的酵母和菌丝体形式中提取的主要中性GSL成分，通过1H和13C NMR光谱、ESI-MS和ESI-MS/CID-MS以及GC-MS进行了纯化和表征。两种形式的主要GSL均被鉴定为β-吡喃葡萄糖基神经酰胺（GlcCer），其长链碱基为（4E，8E）-9-甲基-4,8-鞘氨醇二烯，与N-2'-羟基十八烷酸或N-2'-羟基-（E）-3'-十八碳烯酸结合。菌丝体形式的GlcCer中两种脂肪酸的比例约为1:1，而酵母形式的平均只有约15%的（E）-Δ3-不饱和脂肪酸。来自两株烟曲霉（237和ATCC 9197）同时表达半乳糖神经酰胺（GalCer）和GlcCer的脑苷脂也通过类似方法进行了纯化和表征。发现两株菌株的GalCer组分中分别约有70%和约9%的N-2'-羟基-（E）-3'-十八碳烯酸。相比之下，GlcCer组分中N-2'-羟基-（E）-3'-十八碳烯酸的含量分别仅约为20%和约50%。在所有情况下，其余部分是饱和的2-OH脂肪酸，这在烟曲霉脑苷脂中此前尚未有报道。巴西副球孢子菌糖基肌醇磷酸神经酰胺[Levery, S.B., Toledo, M.S., Straus, A.H., and Takahashi, H.K. (1998) Biochemistry 37, 8764 - 8775]和脑苷脂详细结构的可得性揭示了酵母和菌丝体形式之间表达的平行定量差异，以及两类GSL之间神经酰胺结构的显著总体分配。针对真菌鞘脂可能的功能作用，特别是与巴西副球孢子菌表现出的形态转变相关的功能作用，对这些结果进行了讨论。
