HIGH-AFFINITY BINDING OF THE ENTAMOEBA-HISTOLYTICA LECTIN TO POLYVALENT N-ACETYLGALACTOSAMINIDES
HIGH-AFFINITY BINDING OF THE ENTAMOEBA-HISTOLYTICA LECTIN TO POLYVALENT N-ACETYLGALACTOSAMINIDES
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DOI：
10.1074/jbc.270.10.5164
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发表时间：
1995-03-10
影响因子：
4.8
通讯作者：
SCHNAAR, RL
中科院分区：
文献类型：
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作者：
ADLER, P;WOOD, SJ;SCHNAAR, RL
溶组织内阿米巴滋养体通过阿米巴表面凝集素粘附宿主糖缀合物而启动致病性定植，阿米巴表面凝集素结合半乳糖（Gal）和N-乙酰半乳糖胺（GalNAc）残基。筛选了单价和多价碳水化合物配体对大肠杆菌的抑制作用。溶组织凝集素介导的人红细胞血凝反应，揭示了：（i）合成的多价新糖蛋白GalNAc（39）BSA（平均有39个GalNAc残基与牛血清白蛋白连接）的抑制剂比单价GalNAc强140，000倍，比单价Gal强500，000倍;和（ii）以高亲和力结合哺乳动物肝Gal/GalNAc凝集素的小的合成多价配体不以高亲和力结合E.溶组织凝集素放射性配体结合研究表明I-125-GalNAc（39）BSA与E.溶组织细胞膜（K-D = 10 +/- 3 nM，B-max = 0.9 +/- 0.08 pmol/mg膜蛋白）。最大结合需要氯化钙的存在（300 μ M）或氯化钠（50 mM），并且具有宽的pH最大值（pH 6-9），GalNAc（39）BSA在阻断放射性配体结合方面比单价GalNAc强200，000倍。在合成的糖衍生的线性聚合物中，GalNAc β和GalNAc α 3Gal β衍生物是最有效的，其中GalNAc α和GalNAc α 3（Fuc α 2）Gal β衍生物弱得多。数据支持这样一种模型，其中间隔的多个GalNAc残基的独特模式是E.溶组织凝集素
Entamoeba histolytica trophozoites initiate pathogenic colonization by adherence to host glycoconjugates via an amebic surface lectin which binds to galactose (Gal) and N-acetylgalactosamine (GalNAc) residues. Monovalent and multivalent carbohydrate ligands were screened for inhibition of E. histolytica lectin-mediated human red cell hemagglutination, revealing that: (i) the synthetic multivalent neoglycoprotein GalNAc(39)BSA (having an average of 39 GalNAc residues linked to bovine serum albumin) was 140,000-fold more potent an inhibitor than monovalent GalNAc and 500,000-fold more potent than monovalent Gal; and (ii) small synthetic multivalent ligands which bind with high affinity to the mammalian hepatic Gal/GalNAc lectin do not bind with high affinity to the E. histolytica lectin. Radioligand binding studies revealed saturable binding of I-125-GalNAc(39)BSA to E. histolytica membranes (K-D = 10 +/- 3 nM, B-max = 0.9 +/- 0.08 pmol/mg membrane protein). Maximal binding required the presence of calcium chloride (300 mu M) or sodium chloride (50 mM), and had a broad pH maximum (pH 6-9), GalNAc(39)BSA was 200,000-fold more potent than monovalent GalNAc in blocking radio ligand binding, Among synthetic saccharide-derivatized linear polymers, the GalNAc beta and GalNAc alpha 3Gal beta derivatives were the most potent, with GalNAc alpha and GalNAc alpha 3(Fuc alpha 2)Gal beta derivatives much weaker. The data support a model in which a unique pattern of spaced multiple GalNAc residues are the highest affinity targets for the E. histolytica lectin.