Primary structure and carbohydrate binding specificity of a potent anti-HIV lectin isolated from the filamentous cyanobacterium Oscillatoria agardhii
Primary structure and carbohydrate binding specificity of a potent anti-HIV lectin isolated from the filamentous cyanobacterium Oscillatoria agardhii
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DOI：
10.1074/jbc.m701252200
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发表时间：
2007-04-13
影响因子：
4.8
通讯作者：
Hori, Kanji
中科院分区：
文献类型：
--
作者：
Sato, Yuichiro;Okuyama, Satomi;Hori, Kanji
采用Edman降解和电子喷雾电离-质谱法相结合的方法，从淡水蓝藻O.agardhii NIES-204中分离得到一种凝集素，命名为OAA。OAA是由两个串联重复序列组成的多肽(M-r13,925)。有趣的是，OAA的每个重复序列都与粘杆菌、黄色粘球菌血凝素和海洋红藻Eucheuma Serra凝集素的序列高度相似。与吡啶层状低聚糖的系统结合分析表明，OAA只与高甘露糖(HM)-Typen-Gan结合，而不与其他N-Gan结合，包括复合型、杂交型和糖脂中五糖核心或寡糖。OAA不与任何作为支化低聚甘露糖苷成分的游离单和低聚甘露糖苷相互作用。这些结果表明，核心二糖GlcNAc-GlcNAc也是与OAA结合所必需的。当α1-2 Man连接到从五糖核心的α1-6 Man分支而来的α1-3 Man上时，OAA与HM型N-糖链的结合活性显著降低。OAA对HM类低聚糖的这种特异性有别于其他HM结合凝集素。与HM七糖的动力学分析表明，OAA每个分子有两个碳水化合物结合部位，结合常数为2.41×10(8)M-1。此外，OAA有效地抑制了人类免疫缺陷病毒在MT-4细胞中的复制(EC50=44.5 nM)。因此，我们发现了一个新的凝集素家族，在细菌、蓝藻和海藻中具有相似的结构和碳水化合物结合特异性。
The primary structure of a lectin, designated Oscillatoria agardhii agglutinin (OAA), isolated from the freshwater cyanobacterium O. agardhii NIES-204 was determined by the combination of Edman degradation and electron spray ionization-mass spectrometry. OAA is a polypeptide (M-r 13,925) consisting of two tandem repeats. Interestingly, each repeat sequence of OAA showed a high degree of similarity to those of a myxobacterium, Myxococcus xanthus hemagglutinin, and a marine red alga Eucheuma serra lectin. A systematic binding assay with pyridylaminated oligosaccharides revealed that OAA exclusively binds to high mannose (HM)-typeN-glycans but not to other N-glycans, including complex types, hybrid types, and the pentasaccharide core or oligosaccharides from glycolipids. OAA did not interact with any of free mono- and oligomannoses that are constituents of the branched oligomannosides. These results suggest that the core disaccharide, GlcNAc-GlcNAc, is also essential for binding to OAA. The binding activity of OAA to HM type N-glycans was dramatically decreased when alpha 1 - 2 Man was attached to alpha 1 - 3 Man branched from the alpha 1 - 6 Man of the pentasaccharide core. This specificity of OAA for HM- type oligosaccharides is distinct from other HM- binding lectins. Kinetic analysis with an HM heptasaccharide revealed that OAA possesses two carbohydrate binding sites per molecule, with an association constant of 2.41 x 10(8) M-1. Furthermore, OAA potently inhibits human immunodeficiency virus replication in MT-4 cells (EC50 = 44.5 nM). Thus, we have found a novel lectin family sharing similar structure and carbohydrate binding specificity among bacteria, cyanobacteria, and marine algae.