PDF(Pubmed)
Abstract：
Terminal repeat retrotransposons in miniature (TRIMs) are short non-autonomous long terminal repeat (LTR) retrotransposons found from various eukaryotes. Cassandra is a unique TRIM lineage which contains a 5S rRNA-derived sequence in its LTRs. Here, two new groups of TRIMs, designated Helenus and Ajax, are reported based on bioinformatics analysis and the usage of Repbase. Helenus is found from fungi, animals, and plants, and its LTRs contain a tRNA-like sequence. It includes two LTRs and between them, a primer-binding site (PBS) and polypurine tract (PPT) exist. Fungal and plant Helenus generate 5 bp target site duplications (TSDs) upon integration, while animal Helenus generates 4 bp TSDs. Ajax includes a 5S rRNA-derived sequence in its LTR and is found from two nemertean genomes. Ajax generates 5 bp TSDs upon integration. These results suggest that despite their unique promoters, Helenus and Ajax are TRIMs whose transposition is dependent on autonomous LTR retrotransposon. These TRIMs can originate through an insertion of SINE in an LTR of TRIM. The discovery of Helenus and Ajax suggests the presence of TRIMs with a promoter for RNA polymerase III derived from a small RNA gene, which is here collectively termed TRIMp3.
摘要：
微型末端重复逆转录转座子（TRIM）是来自各种真核生物的短非自主长末端重复（LTR）逆转录转座子。Cassandra是一个独特的TRIM谱系，在其LTR中包含5SrRNA衍生序列。这里,两组新的TRIMs，指定Helenus和Ajax,基于生物信息学分析和Repbase的使用进行了报道。Helenus是从真菌中发现的，动物,和植物,和它的LTR包含一个类似tRNA的序列。它包括两个LTR，它们之间，存在引物结合位点（PBS）和多尿束（PPT）。真菌和植物Helenus在整合后产生5bp的目标位点重复（TSD），而动物Helenus产生4bp的TSD。Ajax在其LTR中包括5SrRNA衍生序列，并从两个nemertean基因组中发现。Ajax在整合后生成5bp的TSD。这些结果表明，尽管它们独特的启动子，Helenus和Ajax是TRIM，其转座依赖于自主LTR反转录转座子。这些TRIM可以通过在TRIM的LTR中插入SINE而产生。Helenus和Ajax的发现表明存在具有源自小RNA基因的RNA聚合酶III启动子的TRIM，这里统称为TRIMp3。
