类大麦属高分子量谷蛋白基因Kx的序列测定及表达

利用SDS-PAGE检测了2份类大麦属(Crithopsis delileana)材料的高分子量谷蛋白亚基组成，并对其中1份材料的x型亚基进行了克隆和测序。结果表明，2份材料具有完全相同的蛋白电泳图谱。在小麦的高分子量区域仅检测到一条蛋白质带，与小麦y型亚基的迁移率接近，但克隆测序表明其为x型高分子量谷蛋白亚基，其编码基因命名为Kx。Kx基因编码区序列长度为2052bp．编码长度为661个氨基酸残基的蛋白质，其序列具有典型的x型高分子量谷蛋白亚基的特征。Kx基因能在原核表达系统内正确表达，其表达蛋白与来源于种子中的Kx亚基的迁移率完全一致。Kx亚基与小麦属A、B和D，山羊草属C和U以及黑麦属R染色体组编码的高分子量谷蛋白亚基氨基酸序列非常相似，但在N和C保守区的氨基酸组成以及重复区长度上与它们存在明显差异。聚类分析可将Kx与Ax1聚类为平行的分支。由此可见，来源于C．delileana的Kx基因为一新的x型高分子量谷蛋白亚基基因。

Sequencing and Expression Analysis of a Novel HMW-glutenin Gene Kx from Crithopsis delileana

Using SDS-PAGE analysis, the High-molecular-weight(HMW) glutenin subunits of two Crithopsis delileana accessions were detected. It was found that the two accessions had the same HMW glutenin subunits. Only one HMW glutenin subunit with the similar electrophoresis mobility to the y-type HMW glutenin subunit of hexaploid wheat was observed in C. delileana. However,It was indicated that this glutenin subunit was an x-type glutenin subunit Kx by gene sequence analysis. The full coding region of Kx gene is 2052bp and could encodes a mature protein with 661 amino acid residues. The Kx gene could be expressed in the bacterial expression system, and the expressed protein had the same electrophoresis mobility as that in the seed of C. delileana. The primary structure of Kx subunit was very similar to the x-type HMW glutenin subunits encoded by the A, B and D genomes of wheat, the C and U genomes of Aegilops, and the R genome of Secale cereale. In the phylogenetic analysis, Kx subunit was clustered together with Ax1 subunit by an interior parallelled branch. In conclsion, Kx gene is a novel x type glutenin subunit gene from C. delileana.