Characterization of the yam tuber storage proteins from Dioscorea batatas exhibiting unique lectin activities
Characterization of the yam tuber storage proteins from Dioscorea batatas exhibiting unique lectin activities
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DOI：
10.1074/jbc.m402139200
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发表时间：
2004-06-18
影响因子：
4.8
通讯作者：
Muramoto, K
中科院分区：
文献类型：
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作者：
Gaidamashvili, M;Ohizumi, Y;Muramoto, K
从甘薯块茎中分离并鉴定了四种主要蛋白质，命名为DB 1、DB 2、DB 3和DB 4。产率比为20：50：20：10。DB 1是甘露糖结合凝集素（20 kDa），由10 kDa的亚基组成，并被归类为单子叶植物甘露糖结合凝集素家族。DB2是一种贮藏蛋白，约占总蛋白的50%，通常称为薯蓣皂苷，由一个31-kDa的亚基组成。根据氨基酸序列分析，DB2为薯蓣皂苷A（dioscorin A）。DB 3是一种麦芽糖结合凝集素，表观分子量为120 kDa，由一个66 kDa亚基和两个31 kDa亚基组成（DB 3S）。66-kDa亚基进一步由两个通过二硫键交联的31-kDa亚基（DB 3L）组成。DB 3L和DB 3S（分别为242和241个氨基酸残基）彼此同源，具有72%的序列同一性。它们与拟南芥阿拉塔的薯蓣皂苷B和薯蓣皂苷A的同源性分别为90%和93%，与拟南芥的碳酸酐酶的同源性约为45%。DB 3S具有位于Cys（28）-Cys（187）的一个链内二硫键，而DB 3L除了链内二硫键（Cys（28）- Cys（188））之外还具有一个链间二硫键（Cys（40）-Cys（40 '））以形成66-kDa亚基。DB 1和DB 3分别以2.7和3.9 μ g/ml凝集兔红细胞。尽管DB2和DB 3之间的结构同源性，但DB2没有凝集素活性。66-kDa亚基本身揭示了DB 3的全部血凝活性，表明DB 3L而不是DB 3S负责该活性。DB_3的血凝活性需要Ca ~（2+）离子的参与，且仅受麦芽糖和低聚麦芽糖（如麦芽糖、麦芽糖和麦芽糖）的抑制。G.麦芽五糖和麦芽六糖），而不是D-葡萄糖。DB 3不能归入任何已知的植物凝集素家族。DB 4是一种几丁质酶，与一种日本野牡丹的酸性几丁质酶同源。DB 1、DB2和DB 3没有显示任何碳酸酐酶、淀粉酶或胰蛋白酶抑制剂活性。这些结果表明，从山药块茎D.甘薯具有独特的凝集素活性。
Four major proteins designated DB1, DB2, DB3, and DB4 were isolated and characterized from the yam tuber Dioscorea batatas. The ratios of their yields were 20: 50: 20: 10. DB1 was a mannose-binding lectin (20 kDa) consisting of 10-kDa subunits and was classified as the monocot mannose-binding lectin family. DB2, accounting for 50% of the total protein, was the storage protein, commonly called dioscorins consisting of a 31-kDa subunit. On the basis of amino acid sequence, DB2 was classified to be dioscorin A. DB3 was a maltose-binding lectin, having an apparent molecular mass of 120 kDa and composed of a 66-kDa subunit and two 31-kDa subunits (DB3S). The 66-kDa subunit was further composed of two 31-kDa subunits (DB3L) cross-linked by disulfide bonds. DB3L and DB3S (242 and 241 amino acid residues, respectively) were homologous with each other with 72% sequence identity. They showed a sequence homology to dioscorin B and dioscorin A from Dioscorea alata, with 90 and 93% identity, respectively, and to carbonic anhydrase from Arabidopsis thaliana with about 45% identity. DB3S had one intrachain disulfide bond located at Cys(28)-Cys(187), whereas DB3L had one interchain disulfide bond (Cys(40) - Cys(40')) in addition to the intrachain disulfide bond (Cys(28) - Cys(188)) to form a 66-kDa subunit. DB1 and DB3 agglutinated rabbit erythrocytes at 2.7 and 3.9 mug/ml, respectively. Despite the structural homology between DB2 and DB3, DB2 had no lectin activity. The 66-kDa subunit itself revealed the full hemagglutinating activity of DB3, indicating that DB3L but not DB3S was responsible for the activity. The hemagglutinating activity of DB3 required Ca2+ ions and was exclusively inhibited by maltose and oligomaltoses ( e. g. maltopentaose and maltohexaose) but not by D-glucose. DB3 could not be classified into any known plant lectin family. DB4 was a chitinase, homologous to an acidic chitinase from Dioscorea japonica. DB1, DB2, and DB3 did not show any activity of carbonic anhydrase, amylase, or trypsin inhibitor activity. These results show that two of the four major proteins isolated from the yam tubers D. batatas have unique lectin activities.