LINEs are retrotransposable elements found in diverse organisms. Their activity is kept in check by several mechanisms, including transcriptional silencing. Here we have analyzed the transcription status of LINE1 copies in the early-branching parasitic protist Entamoeba histolytica. Full-length EhLINE1 encodes ORF1, and ORF2 with reverse transcriptase (RT) and endonuclease (EN) domains. RNA-Seq analysis of EhLINE1 copies (both truncated and full-length) showed unique features. Firstly, although 20/41 transcribed copies were full-length, we failed to detect any full-length transcripts. Rather, sense-strand transcripts mapped to the functional domains- ORF1, RT and EN. Secondly, there was strong antisense transcription specifically from RT domain. No antisense transcripts were seen from ORF1. Antisense RT transcripts did not encode known functional peptides. They could possibly be involved in attenuating translation of RT domain, as we failed to detect ORF2p, whereas ORF1p was detectable. Lack of full-length transcripts and strong antisense RT expression may serve to limit EhLINE1 retrotransposition.

LINE 是在不同生物体中发现的逆转录转座因子。它们的活性受到多种机制的控制，包括转录沉默。在这里，我们分析了早期分支寄生原生生物溶组织内阿米巴中 LINE1 拷贝的转录状态. 全长 EhLINE1 用逆转录酶 (RT) 和核酸内切酶 (EN) 域编码 ORF1 和 ORF2。EhLINE1 拷贝（截断的和全长的）的 RNA-Seq 分析显示出独特的特征。首先，尽管 20/41 转录副本是全长的，但我们未能检测到任何全长转录本。相反，有义链转录物映射到功能域 - ORF1、RT 和 EN。其次，有强的反义转录，特异地来自 RT 域。从 ORF1 没有看到反义转录本。反义 RT 转录本不编码已知的功能肽。它们可能参与减弱 RT 域的翻译，因为我们未能检测到 ORF2p，而 ORF1p 是可检测到的。缺乏全长转录本和强反义 RT 表达可能会限制 EhLINE1 逆转录转座。