水稻U2snRNA基因的分离及结构分析

对水稻(Oryza sativa L.)基因文库中分离到的U2snRNA基因FDRGU2.3进行序列分析,其编码区与小麦(Triticum aestivum L、)、玉米(Zea mays L.)、豌豆(Pisum sativum L.)及拟南芥(Arabidopsis thaliana(L.)Heyhy.)等植物U2基因的同源性均大于80％,且5＇端70个碱基高度保守。在基因编码区上游-70及-30区分别包含有植物UsnRNA基因特有的上游顺序元件(USE)及类TATA元件。同其它植物一样,水稻U2.3snRNA的二级结构也有保守的4个茎环区。其中环Ⅱ的结构与单子叶植物中的小麦和玉米相同,但与双子叶植物的豌豆和拟南芥存在明显差异。环Ⅳ的结构在单子叶和双子叶植物中亦有不同的变化。这些差异可能意味着单子叶和双子叶植物的剪接机构有所区别。

ISOLATION AND STRUCTURE ANALYSIS OF THE RICE U2snRNA GENE

One of the U2snKNA genes in rice (Oryza saliva L.), FDRGU2.3, has been isolated and sequenced. By comparison, rice U2RNA had more than 80% similarity with other plant U2RNAs. It was found that the 70 nucleotides of 5'-terminal were conserved in all sequenced plant U2RNAs. The rice U2.3 gene contained two plant UsnRNA promoter elements, i. e. the upstream sequence element (USE) and TATA-like box, in the - 70 and - 30 regions respectively; the spacer between the two upstream elements were conserved in the plant U2snRNA genes. The U2. 3RNA maintains the conserved U2snRNA secondary structure including four stem-loops. The nucleotide sequence of loop II was the same as that of monocot such as wheat ( Triticum aestivum L.) and maize (Zea mays L.), but distinct from that of dicot such as pea (Fusion sativum L.) and Arabidopsis thaliana (L.) Heynh. The nucleotide sequence of loop IV showed a different variation in monocot and dicot. These suggested that the splicing apparatus between monocot and dicot were different.