绒泡菌目黏菌的ITS1-5.8S-ITS2二级结构的比较分析

Comparative analysis of the secondary structure of ITS1-5.8S-ITS2 r RNA in the myxomycete order Physarales

为探讨核糖体DNA转录间隔区(r DNA ITS)的RNA二级结构在黏菌系统发育研究中的作用,以黏菌ITS通用引物PHYS4和PHYS5对绒泡菌目5属8种黏菌的r DNA ITS进行扩增和测序,利用RNA structure构建了ITS区的RNA二级结构模型。结果表明:ITS1在绒泡菌目黏菌中不能形成一个紧实的结构,但大部分物种都具有一段稳定的螺旋结构,可能对r RNA的成熟具有作用;5.8S r RNA的二级结构相似,由4个螺旋组成,主要为两种类型;基于5.8S r RNA和28S r RNA相互作用构建的ITS2的二级结构模型显示,它由一个封闭的多分支环和至少4个主要的螺旋组成,其中螺旋IV结构相对比较保守。由于ITS区的二级结构相比核苷酸序列更加保守,因此深入地分析其二级结构有助于认识其结构与进化的关系。

In order to explore the function of the secondary structures of internal transcribed spacers region of ribosomal DNA （rDNA ITS） in the phylogenetic analysis of myxomycetes, the universal primers PHYS4 and PHYS5 were used to amplify and sequence the rDNA iTS sequences of in myxomycete species of the order Physarales, and the RNA secondary structures of ITS were calculated and drawn using the program RNA structure. The results indicated that the ITS1 could not form a compact structure, but had a common stable helix structure in most tested Physarales species, probably playing an important role in the processing of mature rRNA. The 5.8S secondary structures in different species were similar each other, which are composed of four helixes with two main types. The ITS2 secondary structure was constructed based on 5.8S rRNA-28S rRNA interaction. A closed multibranch loop and at least four major helixes were predicted with the helix IV being relatively conservative. The secondary structures of ITS regions were more conserved than their nucleotide sequences. Therefore, the further analysis of ITS structures will benefit the understanding of the relationships between the ITS structure and molecular evolution of Physarales species