PIF-like Transposons are common in Drosophila and have been repeatedly domesticated to generate new host genes
PIF-like Transposons are common in Drosophila and have been repeatedly domesticated to generate new host genes
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DOI：
10.1093/molbev/msm116
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发表时间：
2007-08-01
影响因子：
10.7
通讯作者：
Feschotte, Cedric
中科院分区：
文献类型：
--
作者：
Casola, Claudio;Lawing, A. Michelle;Feschotte, Cedric
DNA转座子的P不稳定因子或PIF超家族构成了植物中一类重要的转座元件，但在后生动物中仍未得到很好的描述。利用已有的12种果蝇的基因组草图序列，我们发现了4种不同的果蝇PIF样转座子，命名为DPLTI-4。这些谱系在果蝇辐射期间经历了一段复杂的进化史，涉及物种之间的差异扩增和保留以及可能的水平传播事件。与之前描述的植物和动物PIF转座子一样，全长DPLT编码一个假定的转座酶和一个包含Myb/SANT结构域的第二个预测蛋白。在DPLTS中，该结构域与几种果蝇转录因子中发现的MADF DNA结合结构域关系最密切。此外，我们鉴定了分布在果蝇属中的7个不同的基因，它们编码与PIF转座酶相关的蛋白，但缺乏转座子的特征。相反，这些序列显示了功能基因的特征，例如在纯化选择下进化的完整编码区，至少两个果蝇物种中存在同源基因，以及内含子/外显子结构在同源基因之间的保守性。我们还提供了证据，证明这些基因中的大多数是转录的，有些是发育调节的。总而言之，这些数据表明，这些基因来自PIF转座子，这些转座子已经被“驯化”，以服务于细胞功能。在一个例子中，转座酶基因的募集伴随着相邻的第二个PIF基因的共募集，这提出了这样的假设，即这两种蛋白质现在在相同的途径中发挥作用。第二个PIF基因保留了编码具有完整MADF结构域的蛋白质的能力，表明它可能作为转录因子发挥作用。我们得出结论，PIF转座子在果蝇谱系中很常见，并且在果蝇进化过程中一直是新基因的经常性来源。
The P instability factor or PIF superfamily of DNA transposons constitutes an important group of transposable elements (TEs) in plants, but it is still poorly characterized in metazoans. Taking advantage of the availability of draft genome sequences for twelve Drosophila, species, we discovered 4 different lineages of Drosophila PIF-like transposons, named DPLTI-4. These lineages have experienced a complex evolutionary history during the Drosophila radiation, involving differential amplification and retention among species and probable events of horizontal transmission. Like previously described plant and animal PIF transposons, full-length DPLTs encode a putative transposase as well as a second predicted protein containing a Myb/SANT domain. In DPLTs, this domain is most closely related to the MADF DNA binding domain found in several Drosophila transcription factors. In addition, we identified 7 distinct genes distributed across the Drosophila genus that encode proteins related to PIF transposases, but lack the hallmarks of transposons. Instead, these sequences show features of functional genes, such as an intact coding region evolving under purifying selection, the presence of orthologs in at least 2 Drosophila species, and the conservation of intron/exon structure across orthologs. We also provide evidence that most of these genes are transcribed and that some are developmentally regulated. Together the data indicate that these genes derived from PIF-transposons that have been "domesticated" to serve cellular functions. In one instance the recruitment of the transposase gene was accompanied by the co-recruitment of the adjacent second PIF gene, which raises the hypothesis that both proteins now function in the same pathway. The second PIF gene has retained the capacity to encode a protein with an intact MADF domain, suggesting that it may function as a transcription factor. We conclude that PIF transposons are common in the Drosophila lineage and have been a recurrent source of new genes during Drosophila evolution.