The Major Surface Carbohydrates of the Echinococcus granulosus Cyst: Mucin-Type O-Glycans Decorated by Novel Galactose-Based Structures
The Major Surface Carbohydrates of the Echinococcus granulosus Cyst: Mucin-Type O-Glycans Decorated by Novel Galactose-Based Structures
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DOI：
10.1021/bi901112q
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发表时间：
2009-12-15
期刊：
影响因子：
2.9
通讯作者：
Ferreira, Fernando
中科院分区：
文献类型：
--
作者：
Diaz, Alvaro;Carolina Fontana, E.;Ferreira, Fernando
绦虫是重要的人类和兽医寄生虫，但研究不足。它们的表面富含碳水化合物，但可获得的结构信息很少。细粒棘球绦虫的组织寄居幼虫（包虫囊肿）由富含碳水化合物的细胞外基质的巨大层（称为层压层）向外保护。该层的单糖组成表明其主要碳水化合物组分仅为粘蛋白型O-聚糖。我们在这些聚糖从粗层压层中释放后对其进行了纯化，并通过MS和NMR获得了10种最丰富组分的完整结构。长度在2至6个残基之间的结构包含有限数量的生物合成基序。粘蛋白核心I和2是未修饰的或被Galp β 1-3残基的链延长。该链可以被单个Galp α 1-4残基封端，这种封端随着链尺寸的增加而变得更占优势。此外，核心2 N-乙酰葡糖胺残基有时被二糖Galp α 1-4Galp β 1-4取代，产生血液P-1-抗原基序。较大的，也相关的，聚糖存在，达到至少18个残基的大小。所描述的聚糖是相关的，但大于先前描述的来自多房棘球绦虫粘蛋白的聚糖[Hulsmeier，A. J.，等人（2002）J.Biol.Chem.277，5742-5748]。结果表明，E.颗粒孢囊仅向宿主暴露几种不同的主要碳水化合物基序。这些基序基本上由半乳糖单元组成，并且包括通过（Galp β 1-3）（n）的延伸和通过Galp α 1-4的加帽，这在动物粘蛋白型O-聚糖中是新的。
The cestodes constitute important but understudied human and veterinary parasites. Their surfaces are rich in carbohydrates, on which very little structural information is available. The tissue-dwelling larva (hydatid cyst) of the cestode Echinococcus granulosus is outwardly protected by a massive layer of carbohydrate-rich extracellular matrix, termed the laminated layer. The monosaccharide composition of this layer suggests that its major carbohydrate components are exclusively mucin-type O-glycans. We have purified these glycans after their release from the crude laminated layer and obtained by MS and NMR the complete structure of 10 of the most abundant components. The structures, between two and six residues in length, encompass a limited number of biosynthetic motifs. The mucin cores I and 2 are either nondecorated or elongated by a chain of Galp beta 1-3 residues. This chain can be capped by a single Galp alpha 1-4 residue, such capping becoming more dominant with increasing chain size. In addition, the core 2 N-acetylglucosamine residue is in cases substituted with the disaccharide Galp alpha 1-4Galp beta 1-4, giving rise to the blood P-1-antigen motif. Larger, also related, glycans exist, reaching at least 18 residues in size. The glycans described are related but larger than those previously described from an Echinococcus multilocularis mucin [Hulsmeier, A. J., et al. (2002) J. Biol. Chem. 277, 5742-5748]. Our results reveal that the E. granulosus cyst exposes to the host only a few different major carbohydrate motifs. These motifs are composed essentially of galactose units and include the elongation by (Galp beta 1-3)(n) and the capping by Galp alpha 1-4, novel in animal mucin-type O-glycans.