刚毛柽柳Na^+/H^+逆向转运蛋白基因的克隆与表达分析

Cloning and Expression Analysis of a Plasma Membrane Na^+/H^+Antiporter Gene in Tamarix hispida

通过对刚毛柽柳(Tamarix hispida)转录组分析,鉴定获得一个Na^+/H^+逆向转运蛋白基因,命名为Th SOS1。Th SOS1基因c DNA全长3 917 bp,开放阅读框长3 498 bp,编码1 165个氨基酸,编码蛋白相对分子质量128.8 k Da,理论等电点(PI)为6.42。疏水性分析预测Th SOS1基因编码蛋白N端具有10个跨膜结构域,C端具有一个较长的亲水尾部。Th SOS1氨基酸序列与长叶红砂、藜麦、盐地碱蓬等植物的SOS1序列同源性较高,分别可达92%,73%,72%。系统发育分析表明Th SOS1为质膜型Na^+/H^+逆向转运蛋白,与液泡膜型Na^+/H^+逆向转运蛋白属于不同分支。实时荧光定量RT-PCR分析显示,该基因受高盐、干旱诱导上调表达,暗示Th SOS1可能在刚毛柽柳抗旱耐盐过程中发挥重要作用。

A full length c DNA of a Na＋/ H＋antiporter gene（ named Th SOS1） gene was isolated from the transcriptome c DNA librarys of Tamarix hispida. Th SOS1 was 3 917 bp in length,including an open reading frame of 3 498 bp which was predicted to encode a polypeptide of 1 165 amino acids. The estimated molecular weight and isoelectric point of the putative protein were 128. 8 k Da and 6. 42,respectively. By hydrophobic cluster analysis,Th SOS1 contained 10 potential transmembrane domains within the N- terminal protion and a long hydrophilic cytoplasmic tail in the C-terminal protion. By multiple sequence alignment,Th SOS1 show92%,73%,and 72% identities in amino acid sequence to plasma membrane Na＋/ H＋antiporter genes from Reaumuria trigyna,Chenopodium quinoa and Suaeda salsa. By phylogenetic analysis,Th SOS1 was more related to the plasma membrane-type Na＋/ H＋antiporter and clustered distantly with the vacuolar-typed Na＋/ H＋antiporter. By quantitative real-time PCR assay,the m RNA levels of Th SOS1 was significantly up-regulated in T. hispida under Na Cl and PEG treatments. Therefore,Th SOS1 might play an important role in salt and drought tolerance of T. hispida.