一个小麦ω-醇溶蛋白基因同源序列的分离与序列分析

Isolation and Sequence Analysis of Aω-Gliadin Homologous Gene from Wheat

通过基因组PCR克隆了小麦济南177的一个ω-醇溶蛋白基因同源序列(ω1236),该序列包括部分5′、3′侧翼序列和全部可能的编码序列,没有内含子,但在第87、117、125、160、198、313、357和365氨基酸残基处有终止密码子,所有8个终止密码的形成都是碱基转换的结果。比较分析发现,该序列与一个ω-醇溶蛋白基因序列(AB059812)有98%的同源性。推导的氨基酸序列表明该基因符合禾谷类醇溶蛋白的特点。系统进化分析表明,该序列与小麦ω醇溶蛋白在进化上亲缘关系较近,与α-,β-,γ-醇溶蛋白基因关系较远。ω1236推导的氨基酸序列编码了一个可能的47.2 kDa的蛋白质。转化大肠杆菌发现,在IPTG诱导后最初2 h,有小肽段产生,这说明在该基因序列中可能存在终止密码,这与测序结果是一致的。该研究为用PCR技术克隆ω醇溶蛋白基因和进一步研究ω醇溶蛋白基因的结构和功能积累了资料。

The DNA sequence of a full-length Triticum astivum CV. Jinan 177ω-gliadin homologous gene （ω1236） containing partial 5＇and 3＇ flanking sequences with no intron was cloned by genomic POR-based technology. The ω1236 sequence possibly encoded a putative 47.2 kDa protein except for eight stop codons at amino acid residue positions 87, 117, 125, 157, 198, 313, 357 and 365 respectively. All the eight stop codons were caused by base transition. Sequence analysis revealed that ω1236 had 98% homology to a ω-gliadin gene of wheat （AB059812）. Like all other gliadin gene families characterized in cereals, this gene possessed all the features in other plant reported previously. Phylogenetic analysis of the completely sequenced gene as well as those ω-gliadin genes in wheat, ω-secalin and Chorden genes in rye and barley, and α-,β-, and γ-gliadin genes in wheat indicated that the ω1236 was more closely related to ω-gliadin gene family, much less homology to α-,β-,and γ-gliadin gene families. Short peptide was produced in the culture of transformed E. coil induced by IPTG in early 2 h. It indicated that stop codon would be in ω1236. The result is consistent with that of the sequenced gene. The present paper could accumulate data useful for both ω- gliadin gene cloning by PCR and the study on structures and functions of these genes.