Modulation of the carbohydrate-binding specificity of two Xenopus proto-type galectins by site-directed mutagenesis
Modulation of the carbohydrate-binding specificity of two Xenopus proto-type galectins by site-directed mutagenesis
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通过定点诱变调节两种非洲爪蟾原型半乳糖凝集素的碳水化合物结合特异性
DOI：
10.1016/j.bbapap.2021.140684
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Takanori Nakamura
中科院分区：
文献类型：
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作者：
Yasuhiro Nonaka;Takashi Ogawa;Hiroki Shoji;Nozomu Nishi;Shigehiro Kamitori;Takanori Nakamura
半乳糖凝集素家族是一个代表性的可溶性凝集素家族，其负责多种细胞功能的调节。虽然半乳糖凝集素的碳水化合物结合特异性已被充分研究，蛋白质结构和特异性之间的关系仍有待阐明。我们先前报道了非洲爪蟾半乳糖凝集素的特性，xgalectin-Va，它已经偏离半乳糖凝集素-1。xgalectin-Va的碳水化合物选择性不同于人galectin-I和xgalectin-Ib（非洲爪蟾galectin-I同源物）的碳水化合物选择性。在这项研究中，我们澄清了这种选择性的定点突变的关键残基。Xgalectin-Va的两个氨基酸Val 56 Gly/Lys 76 Arg的取代大大增强了与N-乙酰乳糖胺的结合能力，并赋予显著的T细胞生长抑制活性，尽管野生型没有活性。Galectin-1中的Gly 54和Arg 74这两个残基将协同参与N-乙酰乳糖胺的识别。S4和S5 β链之间的环区参与与TF-抗原二糖的结合。环取代成功地改变了xgalectin-Va和xgalectin-Ib的碳水化合物选择性。
The galectin family is a representative soluble lectin group, which is responsible for the modulation of various cell functions. Although the carbohydrate-binding specificity of galectins has been well-studied, the relationship between protein structure and specificity remains to be elucidated. We previously reported the characteristics of aXenopus laevisskin galectin, xgalectin-Va, which had diverged from galectin-1. The carbohydrate selectivity of xgalectin-Va was different from that of human galectin-1 and xgalectin-Ib (aXenopus laevisgalectin-1 homolog). In this study, we clarified the key residues for this selectivity by site-directed mutagenesis. Substitution of two amino acids of xgalectin-Va, Val56Gly/Lys76Arg, greatly enhanced the binding ability toN-acetyllactosamine and conferred significant T-cell growth inhibition activity, although the wild type had no activity. These two residues, Gly54 and Arg74 in galectin-1, would cooperatively contribute to theN-acetyllactosamine recognition. The loop region between the S4 and S5 β-strands was involved in the binding to the TF-antigen disaccharide. The loop substitution successfully changed the carbohydrate selectivity of xgalectin-Va and xgalectin-Ib.