小麦属Xa 21-类似蛋白激酶基因的克隆及与同源位点序列比较

对小麦属Xa21-类似蛋白激酶基因进行了克隆及与同源序列比较研究.在小麦(Triticum aestivum)高分子量麦谷蛋白基因位点附近有一个编码LRR-类受体蛋白激酶的基因位点(暂标记为TaXa),编码蛋白与水稻(O ryza sativa)抗病蛋白Xa 21类似.通过反转录PCR途径,从普通小麦和二粒小麦(Triticum turgidum)的TaXa同源位点分离了3个cDNA克隆,ZS 860(GenBank查询号:EF 394367),ZS 2000(GenBank查询号:EF 394368)和ZS 2001(GenBank查询号:EF 394369).TaXa位点的祖先基因可能编码1 028个氨基酸组成的多肽.一个完整的TaXa蛋白包括N-端保守区、LRR结构域、一个跨膜区和位于C—端的丝氨酸—苏氨酸蛋白激酶功能域.在基因进化过程中,由于碱基代换、缺失和插入导致了开放读码框的改变,使该位点基因的编码多肽缩短.本研究对小麦属TaXa同源位点编码氨基酸序列和1个大麦(Hordeum vulgare)中的同源蛋白进行了详细比较.

Cloning of Xa 21-Like Protein Kinase Genes and Its Sequence Comparison at the Orthologous Loci in Triticum

Three Xa 21-like protein kinase genes were cloned from Triticum,and the sequences at the orthologous loci were studied.Near the HMW-glutenin gene loci of wheat(Triticum aestivum),there is a locus(temporarily named TaXa) encoding an LRR-receptor like protein kinase,which is homologous to rice (Oryza sativa) disease resistance protein Xa 21.Through RT-PCR approach,three cDNA clones of ZS 860(GenBank accession No.EF 394367),ZS 2000(GenBank accession No.EF 394368) and ZS 2001(GenBank accession No.EF 394369) were isolated at the orthologous loci of TaXa in T.aestivum and Triticum turgidum respectively.The ancestral TaXa locus probably encoded a 1 028 amino acid long peptide.A complete TaXa protein includes a N-terminal conserved sequence, LRR domains,a transmembrane region and a serine/threonine protein kinase domain.Nucleotide base pair substitution,deletion and insertion happened during gene evolution led to the change of the open reading frame,and thus shortened the encoded peptides.The amino acid sequences encoded by TaXa orthologous loci in Triticum and one of Hordeum vulgare were compared in detail.