Allosteric regulation of the carbohydrate-binding ability of a novel conger eel galectin by D-mannoside
Allosteric regulation of the carbohydrate-binding ability of a novel conger eel galectin by D-mannoside
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D-甘露糖苷对新型海鳗半乳糖凝集素碳水化合物结合能力的变构调节
DOI：
10.1074/jbc.m112.346213
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
T. Ogawa
中科院分区：
文献类型：
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作者：
M. Watanabe;O. Nakamura;K. Muramoto;T. Ogawa
长鳗鱼有两种凝集素，称为凝集素I和凝集素II (Con I和II)，它们在粘液中起生物防御分子的作用。Con I和II通过结构域交换获得了新的蛋白质折叠，并通过加速进化获得了新的配体结合位点，从而能够识别某些海洋细菌。在本研究中，我们从长鳗腹膜细胞中鉴定出一种新的凝聚蛋白同型，凝聚蛋白P （conp）。尽管Con-P与半乳糖凝集素具有明显的同源性，但我们观察到在所有其他已知的半乳糖凝集素中保守的碳水化合物识别域的8个氨基酸残基中有7个被取代。为了了解这种独特的凝集素的结构-功能关系，利用Con ii标记的融合蛋白系统成功地在大肠杆菌中表达了重组Con- p，并随后对其进行了表征。在有d-甘露糖存在的情况下，Con- p的血凝活性比Con I高30倍；而不添加甘露糖则没有活性，表明甘露糖可以作为Con-P的调节剂。正面亲和层析分析表明，经甘露糖变构诱导活化的Con-P对寡甘露糖型糖和n-乙酰乳胺型β-半乳糖苷具有亲和性。因此，Con-P代表了具有独特性质的凝集素家族的新成员。
Conger eel has two galectins, termed congerins I and II (Con I and II), that function in mucus as biodefense molecules. Con I and II have acquired a novel protein fold via domain swapping and a new ligand-binding site by accelerated evolution, which enables recognition of some marine bacteria. In this study, we identified a new congerin isotype, congerin P (Con-P), from the peritoneal cells of conger eel. Although Con-P displayed obvious homology with galectins, we observed substitution of 7 out of 8 amino acid residues in the carbohydrate recognition domain that are conserved in all other known galectins. To understand the structure-function relationships of this unique galectin, recombinant Con-P was successfully expressed inEscherichia coliby using a Con II-tagged fusion protein system and subsequently characterized. In the presence ofd-mannose, Con-P displayed 30-fold greater hemagglutinating activity than Con I; however, no activity was observed without mannose, indicating thatd-mannoside can act as a modulator of Con-P. Frontal affinity chromatography analysis showed that activated Con-P, allosterically induced by mannose, displayed affinity for oligomannose-type sugars as well asN-acetyllactosamine-type β-galactosides. Thus, Con-P represents a new member of the galectin family with unique properties.