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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Transposon telomeres are widely distributed in the Drosophila genus: TART elements in the virilis group.
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Transposon telomeres are widely distributed in the Drosophila genus: TART elements in the virilis group.

机译：转座子端粒广泛分布在果蝇属：virilis组的TART元件中。

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Telomeres of most animals, plants, and unicellular eukaryotes are made up of tandem arrays of repeated DNA sequences produced by the enzyme telomerase. Drosophila melanogaster has an unusual variation on this theme; telomeres consist of tandem arrays of sequences produced by successive transpositions of two non-LTR retrotransposons, HeT-A and TART. To explore the phylogenetic distribution of these variant telomeres, we have looked for TART homologues in a distantly related Drosophila species, virilis. We have found elements that, despite many differences in nucleotide sequence, retain significant amino acid similarity to TART from D. melanogaster. These D. virilis TART elements have features that characterize TART elements in D. melanogaster: (i) they are found in tandem arrays on chromosome ends, (ii) they are not found in euchromatin, and (iii) they produce both sense and antisense transcripts, with the antisense RNA being in excess. The D. virilis TART elements have one surprising feature: both of the ORFs contain long stretches of the trinucleotide repeat CAX, encoding polyglutamine (with a few interspersed histidines). These long polyglutamine stretches are conserved in the three D. virilis elements sequenced. They do not interrupt any domains of known function in the TART proteins and are not seen in TART proteins from other species. Comparison of the D. virilis and D. melanogaster telomeres suggests that the retrotransposon mechanism of telomere maintenance may have arisen before the separation of the genus Drosophila.
机译：大多数动物，植物和单细胞真核生物的端粒由端粒酶产生的重复DNA序列的串联阵列组成。果蝇（Drosophila melanogaster）在这个主题上有不同寻常的变化。端粒由两个非LTR逆转座子HeT-A和TART的连续转座产生的序列的串联阵列组成。为了探索这些变体端粒的系统发育分布，我们在远缘的果蝇物种virilis中寻找了TART同源物。我们已经发现，尽管核苷酸序列有许多差异，但它们与D. melanogaster的TART仍具有明显的氨基酸相似性。这些D. virilis TART元素具有表征D. melanogaster中TART元素的特征：（i）在染色体末端的串联阵列中发现，（ii）在常染色质中未发现，并且（iii）它们产生有义和反义转录本，反义RNA过多。 D. virilis TART元件具有一个令人惊讶的特征：两个ORF都包含长链段的三核苷酸重复CAX，编码聚谷氨酰胺（带有一些散在的组氨酸）。这些长的聚谷氨酰胺延伸片段在测序的三个维氏梭菌中保守。它们不会中断TART蛋白中任何已知功能的域，也不会在其他物种的TART蛋白中看到。 D. virilis和D. melanogaster端粒的比较表明端粒维持的逆转座子机制可能在果蝇属分离之前就已经出现。

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