The Key Laboratory of Plant Cell Engineering and Germplasm Innovation of Ministry of Education, School of Life Science, Shandong University, 250100, Jinan, People's Republic of China.
Amino Acids. 2010 Apr;38(4):991-9. doi: 10.1007/s00726-009-0307-y. Epub 2009 May 30.
Wild tall wheatgrass (Lophopyrum elongatum L., 2x = 14) is an important resource for improving bread wheat (Titicum aestivum L.), including HMW-GS and LMW-GS relevant to end-use quality of the wheat flour. A set of 14 distinct sequences were amplified from the genomic DNA of the tall wheatgrass, using degenerate primers targeted at Glu-3, the locus containing the genes encoding the low-molecular weight glutenin subunits (LMW-GS). Three sequences contained an internal stop codon and were classified as pseudogenes. The other 11 all consisted of a single intron-less intact open-reading frame. An alignment of deduced protein sequences showed that the primary structure of all 11 sequences was similar to that of wheat and other wheat-related grass Glu-3 genes. All 11 sequences carried the 14 amino acid residue N-terminal motif MESNIIISFLK/RPWL, and were classified as LMW-m genes, based on the identity of the first amino acid of the mature protein. All but one of the sequences contained seven cysteine residues (the exception had 6). Their repetitive domain differs significantly from that present in Glu-3 genes isolated from the close relative intermediate wheatgrass (Thinopyrum Intermedium, 6x). A phylogenetic analysis showed that the tall wheatgrass sequences were closely related to those of the intermediate wheatgrass, but only distantly so to those from decaploid tall wheatgrass. One of the 11 LMW-GS peptides with a free-cysteine residue was heterologously expressed in E. coli and purified in sufficient scale to perform a flour supplementation test. This showed that the dough strength of bread wheat flour was significantly increased by the presence of the tall wheatgrass LMW-GS.
野生长穗小麦草（Lophopyrum elongatum L.，2x=14）是改良普通小麦（Triticum aestivum L.）的重要资源，包括与小麦粉食用品质相关的高分子量谷蛋白（HMW-GS）和低分子量谷蛋白（LMW-GS）。利用针对Glu-3 设计的简并引物，从长穗小麦草的基因组 DNA 中扩增出了 14 个不同的序列，Glu-3 是编码低分子量谷蛋白亚基（LMW-GS）的基因所在的位点。其中 3 个序列含有一个内部终止密码子，被归类为假基因。其余 11 个序列均由一个内含子缺失的完整开放阅读框组成。推导的蛋白质序列比对表明，这 11 个序列的一级结构与小麦和其他小麦近缘草的 Glu-3 基因相似。所有 11 个序列均携带成熟蛋白 N 端 14 个氨基酸残基的 MESNIIISFLK/RPWL 基序，根据成熟蛋白的第一个氨基酸的同一性，被归类为 LMW-m 基因。除一个序列外（该序列含有 6 个半胱氨酸），其余序列均含有 7 个半胱氨酸残基。它们的重复区与从中等冰草（Thinopyrum Intermedium，6x）中分离的 Glu-3 基因的重复区有显著差异。系统发育分析表明，长穗小麦草序列与中等冰草的序列密切相关，但与十倍体长穗小麦草的序列关系较远。在大肠杆菌中异源表达了 11 个 LMW-GS 肽中的一个含有游离半胱氨酸的肽，并进行了足够规模的纯化以进行面粉补充试验。结果表明，长穗小麦草 LMW-GS 的存在显著增加了普通小麦面粉的面团强度。
