新麦26的α-醇溶蛋白基因克隆与序列分析

Cloning and Sequence Analysis of α-Gliadin Gene in Bread Wheat Xinmai26

α-醇溶蛋白是小麦籽粒中含量最为丰富的蛋白,也是诱发乳糜泻综合症(celiac disease,CD)的主要活性蛋白.为了解优质强筋小麦新麦26(Triticum aestivum L.)的α-醇溶蛋白基因构成和诱发CD的毒性肽段,作者采用AS-PCR方法从新麦26中克隆了63个序列长度为846-942 bp的全长基因,其中30个序列为假基因,33个序列为功能基因,暂定名为XMGli2-1-XMGli2-33.上述基因可编码长度为285-316个氨基酸的蛋白序列,这些序列具有典型的α-醇溶蛋白特征.其中XMGli2-10、XMGli2-19、XMGli2-26、XMGli2-32和XMGli2-33的多聚谷氨酰胺II区还出现了1个额外的半胱氨酸残基,有助于参与形成链间二硫键,与小麦面筋品质呈正效应.在4类诱发CD的毒性肽段中,DQ2.5-glia-α1a的保守性更强,其他毒性肽段的序列变化较大.在XMGli2-20和XMGli2-28中还存在一个LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQ的肽段,具有较强的免疫毒性.

Theα-gliadin is the most abundant protein in wheat grains,which is also the main active protein for inducing celiac disease(CD).In order to understand theα-gliadin gene composition and CD-induced toxic peptide from Xinmai 26,a total of 63 full-length genes with 846-942 bp were cloned by AS-PCR,including 30 pseudogenes and 33 functional genes(tentatively named XMGli2-1-XMGli2-33).The functional proteins were composed of 285-316 amino acids,which exhibited typicalα-gliadin characteristics.One additional cysteine residue was found in the polyglutamine II region of XMGli2-10,XMGli2-19,XMGli2-26,XMGli2-32 and XMGli2-33,which contributed to the formation of interchain disulfide bonds and had a positive effect on wheat gluten quality.In four kinds of CD toxic peptides,DQ2.5-glia-α1 a is more conservative and the sequences of other toxic peptides change greatly.In addition,the LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQ peptides detected in the XMGli2-20 and XMGli2-28 have stronger immune toxicity.