Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
Nucleic Acids Res. 2012 Nov;40(21):10866-77. doi: 10.1093/nar/gks859. Epub 2012 Sep 12.
Non-long terminal repeat (non-LTR) retrotransposons are highly abundant elements that are present in chromosomes throughout the eukaryotic domain of life. The long interspersed nuclear element (LINE-1) (L1) clade of non-LTR retrotransposons has been particularly successful in mammals, accounting for 30-40% of human genome sequence. The current model of LINE retrotransposition, target-primed reverse transcription, culminates in a chromosomally integrated end product. Using a budding yeast model of non-LTR retrotransposition, we show that in addition to producing these 'classical', chromosomally integrated products, a fungal L1 clade member (Zorro3) can generate abundant, RNA-derived episomal products. Genetic evidence suggests that these products are likely to be formed via a variation of target-primed reverse transcription. These episomal products are a previously unseen alternative fate of LINE retrotransposition, and may represent an unexpected source for de novo retrotransposition.
非长末端重复（non-LTR）反转录转座子是高度丰富的元件，存在于真核生物域的染色体中。非 LTR 反转录转座子的长散布核元件（LINE-1）（L1）分支在哺乳动物中特别成功，占人类基因组序列的 30-40%。LINE 反转录转座的现行模型是靶标引发的逆转录，最终产生染色体整合的终产物。使用非 LTR 反转录的芽殖酵母模型，我们表明，除了产生这些“经典”的染色体整合产物外，真菌 L1 分支成员（Zorro3）还可以产生丰富的 RNA 衍生的附加体产物。遗传证据表明，这些产物可能是通过靶标引发的逆转录的变化形成的。这些附加体产物是 LINE 反转录转座的一个以前未见的替代命运，可能代表从头反转录转座的意外来源。
