植物活性长末端重复序列反转录转座子研究进展

Plant active LTR retrotransposons: a review

摘要:

长末端重复序列 (Long terminal repeat，LTR) 反转录转座子是真核生物基因组中普遍存在的一类可移动的DNA序列，它们以RNA为媒介，通过“复制粘贴”机制在基因组中不断自我复制。在高等植物中，许多活性的LTR反转录转座子已被详尽研究并应用于分子标记技术、基因标签、插入型突变及基因功能等分析。本文对植物活性LTR反转录转座子进行全面的调查，并对其结构、拷贝数和分布以及转座特性进行系统的归纳，分析了植物活性LTR反转录转座子的gag (种属特异抗原) 和pol (聚合酶) 序列特征，以及LTR序列中顺式调控元件的分布。研究发现自主有活性的LTR反转录转座子必须具备LTR区域以及编码Gag、Pr、Int、Rt和Rh蛋白的基因区。其中两端LTR区域具有高度同源性且富含顺式调控元件；Rt蛋白必备RVT结构域；Rh蛋白必备RNase_H1_RT结构域。这些结果为后续植物活性LTR反转录转座子的鉴定和功能分析奠定了重要 基础。

Abstract:

Long terminal repeat (LTR) retrotransposons are mobile DNA sequences that ubiquitously exist in eukaryotic genomes. They replicate themselves in the genome by copy-paste mechanism with RNA as medium. In higher plants, many active LTR retrotransposons have been applied to analyze molecular marker technology, genetic tagging, insertion mutation and gene function. Here, we systematically review the characteristics of plant active LTR retrotransposons, including their structures, copy numbers and distributions. We further analyzed the gag (group-specific antigen) and pol (polymerase) sequence features of different plants active LTR retrotransposons and the distribution patterns of the cis-acting elements in LTR (1ong terminal repeat) regions. The results show that autonomous active LTR retrotransposons must contain LTR regions and code Gag, Pr, Int, Rt, Rh proteins. Both LTR regions are highly homologous with each other and contain many cis-regulatory elements; RVT and RNase_H1_RT domain are essential for Rt and Rh protein respectively. These results provide the basis for subsequent identification of plant active LTR retrotransposons and their functional analysis.