α-醇溶蛋白是小麦籽粒贮藏蛋白的重要组分,其组成与含量对小麦加工品质具有重要影响。利用PCR从郑丰5号基因组中克隆α-醇溶蛋白基因,并对其序列进行分析。经克隆共获得32个α-醇溶蛋白新基因(ZF5A-1～ZF5A-32,GenBank注册序列号为JX828280～JX828311),其中15个为假基因,17个(ZF5A-1～ZF5A-17)具有完整开放阅读框。17个α-醇溶蛋白新基因中,除ZF5A-1、ZF5A-3、ZF5A-6、ZF5A-9、ZF5A-10、ZF5A-11、ZF5A-15编码的蛋白在特征Ⅱ区含有1个额外的半胱氨酸(C)外,其他10个基因编码的蛋白均具有α-醇溶蛋白的典型结构。根据推断氨基酸序列中4种主要T细胞优势多肽的分布及多聚谷氨酰胺区的长度,推测ZF5A-7和ZF5A-12可能定位于6A染色体,ZF5A-4、ZF5A-13、ZF5A-14和ZF5A-17可能定位于6B染色体,而ZF5A-1～ZF5A-3、ZF5A-5、ZF5A-6、ZF5A-8～ZF5A-11、ZF5A-15和ZF5A-16可能定位于6D染色体。17个新克隆α-醇溶蛋白基因及4个已知α-醇溶蛋白基因编码的蛋白的二级结构预测结果表明:α-螺旋、β-折叠的位置和核心序列是相对保守的,但不同蛋白α-螺旋和β-折叠的数量以及参与形成同一保守区域α-螺旋和β-折叠的氨基酸残基数却并不相同。克隆的17个α-醇溶蛋白基因中,除ZF5A-17编码的蛋白缺少α-螺旋(H2)、ZF5A-2、ZF5A-8编码的蛋白在特征区Ⅰ均存在1个额外的α-螺旋(HE1)、GQ891685和ZF5A-15编码的蛋白在多聚谷氨酰胺Ⅱ区存在1个额外的α-螺旋(HE2)外,5个保守的α-螺旋(H1～H5)恒定出现在其他基因的2个谷氨酰胺重复区和特征区中;此外,在C-末端特征区大部分基因(61.11%)还形成1个β-折叠结构(E)。郑丰5号中具有较多额外半胱氨酸、α-螺旋和β-折叠的α-醇溶蛋白基因,可能与其良好的加工品质密切相关。
The－ gliadins are the important components of seed strorage proteins，and their composition and content play a major role in determining the processing quality of wheat．Using PCR technology，total 32 novel genes (Designated as ZF5A- 1－ ZF5A-32; GenBank No: JX828280－JX828311 ) were cloned from the wheat cultivar Zhengfeng 5，including 17 full- ORF－ gliadin genes(Designated as ZF5A-1－ZF5A-17) and 15 pseudogenes.The sequence analysis of deduced amino acids showed that 10 had the typical structural characteristics of－ gliadin genes reported previously，and 7(ZF5A-1，ZF5A-3，ZF5A-6，ZF5A-9，ZF5A-10，ZF5A-11，ZF5A-15) possessed an additional cysteine residue in the unique domain ．Based on the occurrence of the four major T cell immunogenic peptides and glutamine residues in the glutamine repeats，ZF5A- 7and ZF5A-12 could be assigned to chromosome 6A，ZF5A-4,ZF5A-13，ZF5A-14 and ZF5A-17 to chromosome 6B，and other 11 genes to chromosome 6D．The sec- ondary structure predication of 17 cloned genes and other four genes in public database demonstrated that the num- bers and distributions of-helix and-strand were variable in different mature-gliadins．Generally，5- helixes (H1－H5) usually presented in the two glutamine repeats and two unique domains for majority of- gliadins，but theputative proteins of ZF5A-17 lost the- helix(H2 )，ZF5A-2 and ZF5A-8 had an additional-helix in the uni domain (HE1 )，and GQ891685 and ZF5A- 15 had an additional- helix in the second glutamine repeat(HE2 ) addition,most of the genes(61．11%) had a-strand(E) in the C-terminal unique domain ．High variations numbers of cysteine residue,-helixes and-strands in the-gliadins of Zhengfeng 5 might be strongly related its good rheological properties of dough．
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