Diversification and collapse of a telomere elongation mechanism.
Diversification and collapse of a telomere elongation mechanism.
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端粒延长机制的多样化和崩溃。
DOI：
10.1101/gr.245001.118
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发表时间：
2019
期刊：
影响因子：
7
通讯作者：
Levine,MiaT
中科院分区：
文献类型：
--
作者：
Saint-Leandre,Bastien;Nguyen,SonC;Levine,MiaT
在大多数真核生物中，端粒酶通过在末端增加重复序列来抵消染色体的侵蚀，而果蝇则依赖于专门插入端粒的反转录转座子。宿主和移动元件之间的这种商品交换--其中移动元件提供基本的基因组服务，而宿主为移动元件繁殖提供友好的利基--被称为“基因组共生”。然而，这些端粒专门化的骑师家族反转录转座子实际上可能会进化成在它们表面上服务的基因组中“自私地”过度复制。在这一模式下，我们预计端粒专门化反转录转座子谱系的迅速多样化，以及这种表面上的共生关系的破裂。在这里，我们报告的数据与这两个预测一致。搜索15-Myr年龄组的黑色素瘤物种组的原始读物，我们产生了de novojockey逆转座子共识序列，并使用系统发育树构建来描绘四个不同的端粒相关谱系。反转录转座子谱系多样性的原因是经常性的获得、损失和替换。在果蝇双足动物中，端粒特化元件已经完全消失。长片段的从头组装和细胞遗传学证实了这种依赖于反转录转座子的端粒延长的物种特异性崩溃。相反，端粒受限的卫星DNA和DNA转座子片段占据了它的末端。我们推断。相反，两足动物依赖于一种基于重组的机制，这种机制从酵母到苍蝇再到人类都是保守的。端粒反转录转座子的多样化和消失表明，持续“自私”的机器塑造了跨越果蝇羽毛的端粒延长，而不是完全驯化的、共生的移动元件。
In most eukaryotes, telomerase counteracts chromosome erosion by adding repetitive sequence to terminal ends.Drosophila melanogasterinstead relies on specialized retrotransposons that insert exclusively at telomeres. This exchange of goods between host and mobile element—wherein the mobile element provides an essential genome service and the host provides a hospitable niche for mobile element propagation—has been called a “genomic symbiosis.” However, these telomere-specialized,jockeyfamily retrotransposons may actually evolve to “selfishly” overreplicate in the genomes that they ostensibly serve. Under this model, we expect rapid diversification of telomere-specialized retrotransposon lineages and, possibly, the breakdown of this ostensibly symbiotic relationship. Here we report data consistent with both predictions. Searching the raw reads of the 15-Myr-oldmelanogasterspecies group, we generated de novojockeyretrotransposon consensus sequences and used phylogenetic tree-building to delineate four distinct telomere-associated lineages. Recurrent gains, losses, and replacements account for this retrotransposon lineage diversity. InDrosophila biarmipes, telomere-specialized elements have disappeared completely. De novo assembly of long reads and cytogenetics confirmed this species-specific collapse of retrotransposon-dependent telomere elongation. Instead, telomere-restricted satellite DNA and DNA transposon fragments occupy its terminal ends. We infer thatD. biarmipesrelies instead on a recombination-based mechanism conserved from yeast to flies to humans. Telomeric retrotransposon diversification and disappearance suggest that persistently “selfish” machinery shapes telomere elongation acrossDrosophilarather than completely domesticated, symbiotic mobile elements.