Cloning and sequencing of a gene encoding a 2S albumin seed storage protein precursor from English walnut (Juglans regia), a major food allergen
Cloning and sequencing of a gene encoding a 2S albumin seed storage protein precursor from English walnut (Juglans regia), a major food allergen
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DOI：
10.1016/s0091-6749(98)70308-2
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发表时间：
1998-06-01
影响因子：
14.2
通讯作者：
Sellers, CL
中科院分区：
文献类型：
--
作者：
Teuber, SS;Dandekar, AM;Sellers, CL
背景资料：核桃在美国的坚果人均消费量中排名第三，并且可以与某些个体的系统性IgE介导的反应相关。目的：本研究的目的是克隆编码核桃仁中的主要食物过敏原之一的基因，并表征重组过敏原。以核桃体细胞胚为材料，构建了λ载体Uni-ZAP中的cDNA表达文库，并利用免疫印迹法对患者血清进行了筛选。鉴定了一个含有663 bp插入片段的cDNA克隆，命名为Jug r I。DNA序列分析表明，该克隆编码一个142个氨基酸的蛋白质，与巴西坚果（Bertholletia excelsa）富含甲硫氨酸的2S白蛋白种子贮藏蛋白前体Ber e 1具有46.1%的同源性。Jug r 1似乎是一种重要的核桃食物过敏原; 16例对核桃过敏的患者血清中有12例显示IgE与2S白蛋白种子贮藏蛋白前体融合蛋白结合。一项IgE结合抑制研究表明，核桃28蛋白前体经过翻译后修饰成为大小亚基，与蓖麻籽、棉籽、芥菜籽和巴西坚果28种子贮藏蛋白过敏原相似，有趣的是，在巴西坚果中编码这种过敏蛋白的基因最近已经声名狼借，因为它被实验性地用作转基因来提高巴西坚果的营养质量。结论：这是目前证实的第六种确定的28白蛋白种子贮藏蛋白结合IgE，表明这类蛋白质是固有的过敏原。
Background: Walnuts rank third in per capita consumption of tree nuts in the United States and can be associated with systemic IgE-mediated reactions in some individuals.Objective: The objectives of the study were to clone a gene encoding one of the major food allergens in the walnut kernel and to characterize the recombinant allergen,Methods: A cDNA expression library in the lambda vector Uni-ZAP, which was prepared from walnut somatic embryos, was screened by using a patient's sera that reacted with multiple protein bands on immunoblotting.Results: A cDNA clone containing an insert of 663 bp was identified and named Jug r I. DNA sequence analysis of this clone revealed that it encoded a protein 142 amino acids in length, Comparison of the encoded protein sequences with protein databases revealed that this clone exhibits a 46.1% identity with the Brazil nut (Bertholletia excelsa) methionine-rich 2S albumin seed storage protein precursor, Ber e 1. Jug r 1 appears to be an important walnut food allergen; 12 of 16 sera from patients allergic to walnuts demonstrated IgE binding to the 2S albumin seed storage protein precursor fusion protein. An IgE-binding inhibition study suggests that the walnut 28 protein precursor undergoes posttranslational modification into a large and small subunit that is similar to castor seed, cottonseed, mustard seed, and Brazil nut 28 seed storage protein allergens, Interestingly, the gene encoding this allergenic protein in Brazil nuts has recently gained notoriety because of its experimental use as a transgene to enhance the nutritional quality of legumes.Conclusion: This is now the sixth definitive 28 albumin seed storage protein demonstrated to bind IgE, suggesting that this class of proteins is inherently allergenic.