小麦甲基转移酶基因TaDnMT2的克隆及特性分析

依赖于DNA甲基化的基因表达调控在植物生长发育过程中发挥重要功能,而DNA甲基转移酶是调节DNA甲基化模式的功能蛋白之一。本研究采用RACE技术克隆了小麦甲基转移酶基因TaDnMT2的包含完整编码区的cDNA序列,并系统分析了该基因的结构特征及其在小麦生长发育过程中的表达特性。结果表明,TaDnMT2的cDNA序列为1321bp（GenBank登录号：JN642641）,其中5′-和3′-UTR（非翻译区）分别为84和115bp、ORF（开放阅读框）1122bp;TaDnMT2编码的氨基酸序列包含2个S-腺苷甲硫氨酸结合域（I和X）、甲基转移酶活性位点（IV）、靶胞嘧啶结合位点（VI）、中和DNA骨架负电荷域（VIII）和靶位点识别区（IX）6个高度保守域,属于DNA甲基转移酶家族的DnMT2亚类;三维结构预测显示,TaDnMT2蛋白可以形成包括7个β-折叠和4个α-螺旋的特定空间结构。表达特性分析的结果表明,TaDnMT2基因在‘京841’小麦不同发育时期的叶中表达量均较高,且其在三叶龄期和五叶龄期的表达量受春化处理的影响;在种子发育过程中,该基因在授粉后5d的种子中表达量较高,随着种子发育进程的推进其表达水平呈逐渐下降趋势;在不同发育时期的根系中,TaDnMT2基因均具有较高水平的表达,且在分蘖期根系中的表达量最高。推断TaDnMT2基因可能在小麦生长发育过程中发挥重要功能。

Cloning and Characterization of Methyltransferase Gene TaDnMT2 in Wheat（Triticum aestivum L.）

DNA methylation-dependent regulation of gene expression plays important roles during the growth and development of plant,and DNA methyltransferase is one of the key regulators which manipulate the patterns of DNA methylation.In this study,the cDNA（including complete coding region） of a wheat（Triticum aestivum） DNA methyltransferase gene TaDnMT2 was cloned by using the RACE technology,and the structural characteristics of the gene,as well as its expression patterns during the growth and development of wheat were analyzed.The cDNA length of TaDnMT2 was 1 321 bp（GenBank accession No.JN642641）,which including 84 bp of 5＇-UTR（untranslated region）,115 bp of 3＇-UTR and 1 122 bp of ORF（open reading frame）.The further analysis indicates that the deduced protein TaDnMT2 contains 6 highly conserved motifs,which including 2 AdoMet binding motifs（I and X）,methyltransferase active site（IV）,target cytosine binding motif（VI）,DNA neutralization motif（VIII） and the target recognition domain（IX）.Phylogenetic analysis indicates that TaDnMT2 is sorted to the DnMT2 sub-class of the plant DNA methyltransferase family.The 3D structure prediction showed that TaDnMT2 could fold to a specific spatial structure including 7 β-sheets and 4 α-helixes.The expression analysis of TaDnMT2 indicated that the gene was highly expressed in leaves at different developing stages in wheat variety ＇Jing841＇ and it＇s expression levels were changed at three-and five-leaf stages due to the vernalization treatment.In developing seeds,the TaDnMT2 was highly expressed at the time point of 5 d after pollination and it＇s expression level was gradually decreased during the seed development.In roots,the expression of TaDnMT2 was generally higher and the highest expression was detected at tillering stage.It is deduced that the TaDnMT2 may play important roles during the wheat growth and development.