Lectins have come a long way from being identified as proteins that agglutinate cells to promising therapeutic agents in modern medicine. Through their specific binding property, they have proven to be anti-cancer, anti-insect, anti-viral agents without affecting the non-target cells. The Arisaema tortuosum lectin (ATL) is a known anti-insect and anti-cancer candidate, also has interesting physical properties. In the present work, its carbohydrate binding behavior is investigated in detail, along with its anti-proliferative property. The microcalorimetry of ATL with a complex glycoprotein asialofetuin demonstrated trivalency contributed by multiple binding sites and enthalpically driven spontaneous association. The complex sugar specificity of ATL towards multiple sugars was also demonstrated in glycan array analysis in which the trimannosyl pentasaccharide core N-glycan [Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAcβ] was the highest binding motif. The high binding glycans for ATL were high mannans, complex N-glycans, core fucosylated N-glycans and glycans with terminal lactosamine units attached to pentasaccharide core. ATL induced cell death in IMR-32 cells was observed as time dependent loss in cell number, formation of apoptotic bodies and DNA damage. As a first report of molecular cloning of ATL, the in silico analysis of its cDNA revealed ATL to be a β-sheet rich heterotetramer. A homology model of ATL showed beta prism architecture in each monomer with 85% residues in favoured region of Ramachandran plot. Detailed exploration of carbohydrate binding behavior indicated ATL specificity towards complex glycans, while no binding to simple sugars, including mannose. Sequence analysis of ATL cDNA revealed that during the tandem evolutionary events, domain duplication and mutations lead to the loss of mannose specificity, acquiring of new sugar specificity towards complex sugars. It also resulted in the formation of a two-domain single chain polypeptide with both domains having different binding sites due to mutations within the consensus carbohydrate recognition sites [QXDXNXVXY]. This unique sugar specificity can account for its significant biological properties. Overall finding of present work signifies anti-cancer, anti-insect and anti-viral potential of ATL making it an interesting molecule for future research and/or theragnostic applications.

中文翻译：

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蛇纹天南星凝集素碳水化合物结合行为和抗增殖活性的探索。


凝集素从被鉴定为凝集细胞的蛋白质到现代医学中有希望的治疗剂，已经走过了很长的路。通过其特异性结合特性，它们已被证明具有抗癌、抗昆虫、抗病毒作用，且不会影响非靶细胞。 Arisaema tortuosum 凝集素 (ATL) 是一种已知的抗昆虫和抗癌候选药物，还具有有趣的物理特性。在目前的工作中，详细研究了其碳水化合物结合行为及其抗增殖特性。 ATL 与复杂糖蛋白脱唾液酸胎球蛋白的微量热分析表明，多结合位点和热函驱动的自发缔合促成了三价性。 ATL 对多种糖的复合糖特异性也在聚糖阵列分析中得到证明，其中三甘露糖基五糖核心 N-聚糖 [Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAcβ] 是最高的结合基序。 ATL 的高结合聚糖是高甘露聚糖、复合 N-聚糖、核心岩藻糖基化 N-聚糖和末端乳糖胺单元连接到五糖核心的聚糖。观察到 ATL 诱导的 IMR-32 细胞死亡，表现为细胞数量的时间依赖性损失、凋亡小体的形成和 DNA 损伤。作为 ATL 分子克隆的第一份报告，对其 cDNA 的计算机分析表明 ATL 是富含 β-折叠的异四聚体。 ATL 的同源模型显示每个单体具有 β 棱柱结构，在 Ramachandran 图的有利区域中具有 85% 的残基。对碳水化合物结合行为的详细探索表明 ATL 对复杂聚糖具有特异性，但不与简单糖（包括甘露糖）结合。 ATL cDNA 的序列分析表明，在串联进化事件中，结构域重复和突变导致甘露糖特异性的丧失，获得对复合糖的新糖特异性。它还导致形成双结构域单链多肽，其中两个结构域由于共有碳水化合物识别位点[QXDXNXVXY]内的突变而具有不同的结合位点。这种独特的糖特异性可以解释其重要的生物学特性。目前工作的总体发现表明 ATL 具有抗癌、抗昆虫和抗病毒潜力，使其成为未来研究和/或治疗诊断应用的有趣分子。