Molecular mechanisms of integration site selection by Dictyostelium retrotransponsons

反转录转座子通过产生它们自己的RNA的DNA拷贝来扩增，然后将其整合到宿主细胞基因组中的新位点。在基因密集的基因组中，活跃复制的反转录转座子引起插入突变的持续威胁。社会性变形虫盘基网柄阿米巴的基因组含有反转录转座子，其优先插入在tRNA基因附近以避免蛋白质编码基因的插入突变。我们先前对逆转录转座子TRE 5-A的研究表明，逆转录转座子编码的蛋白质与tRNA基因特异性转录因子TFIIIB亚基之间的特异性相互作用介导tRNA基因上游的整合。在这个项目中，我们将评估的假设，另外两个tRNA基因特异性反转录转座子在D。discoideum基因组还通过与tRNA基因特异性转录因子的蛋白质-蛋白质接触来识别整合位点。我们将研究逆转录转座子TRE 3-A，其在遗传学上与TRE 5-A相关，但整合在tRNA基因的3'区域，以及DGLT-A，其整合与TRE 5-A相似的tRNA基因的5'，但属于不同的逆转录转座子组。

Retrotransposons amplify by producing DNA copies of their own RNA, which then integrate at new sites in the host cell genome. In gene-dense genomes, the actively replicating retrotransposons cause a constant threat of insertional mutagenesis. The genome of the social amoeba Dictyostelium dis-coideum contains retrotransposons that insert preferentially in the vicinity of tRNA genes to avoid insertional mutagenesis of protein-coding genes. Our previous studies on the retrotransposon TRE5-A suggest that specific interactions between a retrotransposon-encoded protein and subunits of the tRNA gene-specific transcription factor TFIIIB mediate integration upstream of tRNA genes. In this project, we will evaluate the hypothesis that two other tRNA gene-specific retrotransposons in the D. discoideum genome also recognize integration sites by protein-protein contacts with tRNA gene-specific transcription factors. We will investigate retrotransposon TRE3-A, which is phylogenetically related to TRE5-A but integrates in the 3' region of tRNA genes, and DGLT-A, which integrates 5' of tRNA genes similar to TRE5-A but belongs to a different retrotransposon group.