Laboratory of Biochemistry and Glycobiology, Department of Molecular Biotechnology, Ghent University, Coupure links 653, 9000 Ghent, Belgium.
Glycoconj J. 2012 Oct;29(7):467-79. doi: 10.1007/s10719-012-9405-2. Epub 2012 Jun 10.
Rice (Oryza sativa) expresses different putative carbohydrate-binding proteins belonging to the class of lectins containing an Euonymus lectin (EUL)-related domain, one of them being OrysaEULS2. The OrysaEULS2 sequence consists of a 56 amino acid N-terminal domain followed by the EUL sequence. In this paper the original sequence of the EUL domain of OrysaEULS2 and some mutant forms have been expressed in Pichia pastoris. Subsequently, the recombinant proteins were purified and their carbohydrate binding properties determined. Analysis of the original protein on the glycan array revealed interaction with mannose containing structures and to a lesser extent with glycans containing lactosamine related structures. It was shown that mutation of tryptophan residue 134 into leucine resulted in an almost complete loss of carbohydrate binding activity of OrysaEULS2. Our results show that the EUL domain in OrysaEULS2 interacts with glycan structures, and hence can be considered as a lectin. However, the binding of the protein with the array is much weaker than that of other EUL-related lectins. Furthermore, our results indicate that gene divergence within the family of EUL-related lectins lead to changes in carbohydrate binding specificity.
水稻（Oryza sativa）表达了不同的假定碳水化合物结合蛋白，属于含有 Euonymus lectin（EUL）相关结构域的凝集素类，其中之一是 OrysaEULS2。OrysaEULS2 序列由 56 个氨基酸的 N 端结构域组成，其后是 EUL 序列。在本文中，OrysaEULS2 的 EUL 结构域的原始序列和一些突变形式已在毕赤酵母中表达。随后，纯化了重组蛋白并测定了其碳水化合物结合特性。对原始蛋白在糖组芯片上的分析表明，它与含有甘露糖的结构相互作用，并且在较小程度上与含有乳糖胺相关结构的聚糖相互作用。结果表明，将色氨酸残基 134 突变为亮氨酸会导致 OrysaEULS2 的碳水化合物结合活性几乎完全丧失。我们的结果表明，OrysaEULS2 中的 EUL 结构域与糖基结构相互作用，因此可以被视为凝集素。然而，该蛋白与芯片的结合比其他 EUL 相关凝集素弱得多。此外，我们的结果表明，EUL 相关凝集素家族内的基因分化导致碳水化合物结合特异性的变化。
