McConville M J, Bacic A
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.
Mol Biochem Parasitol. 1990 Jan 1;38(1):57-67. doi: 10.1016/0166-6851(90)90205-z.
The glycolipid profiles of two Leishmania major strains which differ in their expression of the major glycoconjugate, lipophosphoglycan (LPG), have been compared. All the glycolipids in these strains belong to a class of glycoinositolphospholipids (GIPLs) which can be metabolically labelled with [3H]inositol and are sensitive to phosphatidylinositol-specific phospholipase C. The major glycolipids in the LPG-producing L. major strain V121 are tetraglycosyl phosphatidylinositol (GIPL-1), pentaglycosyl phosphatidylinositol (GIPL-2), hexaglycosyl phosphatidylinositol (GIPL-3) and lyso-GIPL-3. These were identified by their sensitivity to lipases, and by BioGel P4 chromatography of the glycan fragments released after nitrous acid deamination. Similar glycolipids are also present in the LPG-deficient L. major strain LRC-L119. However, this strain also produces several highly polar GIPLs (GIPL-4, 5 and 6) which are absent from V121 and which may represent truncated forms of LPG. Evidence is presented showing that the LPG and GIPLs from both strains contain galactofuranose, based on identification of labelled arabinose after mild periodate oxidation and reduction with NaB [3H]4. Furthermore, analysis of the deaminated glycan moieties after mild acid hydrolysis suggests that the GIPLs and the glycolipid anchor of LPG contain a common glycan core, which includes the galactofuranose. Finally, radiolabelling of intact cells indicates that there is restricted expression of some of the GIPLs in the plasma membrane and that the GIPL-2 is the predominant cell surface glycolipid. These data are consistent with some, but not all, of the GIPLs in V121 having a major role as precursors to the glycolipid core of LPG.
对两种主要利什曼原虫菌株的糖脂谱进行了比较，这两种菌株在主要糖缀合物脂磷酸聚糖（LPG）的表达上存在差异。这些菌株中的所有糖脂都属于一类糖基肌醇磷脂（GIPLs），它们可以用[3H]肌醇进行代谢标记，并且对磷脂酰肌醇特异性磷脂酶C敏感。产生LPG的主要利什曼原虫菌株V121中的主要糖脂是四糖基磷脂酰肌醇（GIPL-1）、五糖基磷脂酰肌醇（GIPL-2）、六糖基磷脂酰肌醇（GIPL-3）和溶血-GIPL-3。通过它们对脂肪酶的敏感性以及对亚硝酸脱氨后释放的聚糖片段进行BioGel P4色谱分析来鉴定这些糖脂。在缺乏LPG的主要利什曼原虫菌株LRC-L119中也存在类似的糖脂。然而，该菌株还产生了几种高度极性的GIPLs（GIPL-4、5和6），V121中不存在这些GIPLs，它们可能代表LPG的截短形式。基于用NaB[3H]4进行温和过碘酸盐氧化和还原后对标记阿拉伯糖的鉴定，有证据表明来自两种菌株的LPG和GIPLs都含有呋喃半乳糖。此外，对温和酸水解后的脱氨聚糖部分的分析表明，GIPLs和LPG的糖脂锚含有一个共同的聚糖核心，其中包括呋喃半乳糖。最后，完整细胞的放射性标记表明，一些GIPLs在质膜中的表达受到限制，并且GIPL-2是主要的细胞表面糖脂。这些数据与V121中的一些（但不是全部）GIPLs作为LPG糖脂核心的前体发挥主要作用是一致的。
