The twister ribozyme is widely distributed over numerous organisms and is especially abundant in Schistosoma mansoni, but has no confirmed biological function. Of the 17 non-LTR retrotransposons known in S. mansoni, none have thus far been associated with ribozymes. Here we report the identification of novel twister variant (T-variant) ribozymes and their function in S. mansoni non-LTR retrotransposition. We show that T-variant ribozymes are located at the 5′ end of Perere-3 non-LTR retrotransposons in the S. mansoni genome. T-variant ribozymes were demonstrated to be catalytically active in vitro. In reporter constructs, T-variants were shown to cleave in vivo, and cleavage of T-variants was sufficient for the translation of downstream reporter genes. Our analysis shows that the T-variants and Perere-3 are transcribed together. Target site duplications (TSDs); markers of target-primed reverse transcription (TPRT) and footmarks of retrotransposition, are located adjacent to the T-variant cleavage site and suggest that T-variant cleavage has taken place inS. mansoni. Sequence heterogeneity in the TSDs indicates that Perere-3 retrotransposition is not site-specific. The TSD sequences contribute to the 5′ end of the terminal ribozyme helix (P1 stem). Based on these results we conclude that T-variants have a functional role in Perere-3 retrotransposition.

中文翻译：

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扭曲核酶变异体在曼氏血吸虫非 LTR 逆转录转座中的作用

捻线虫​​核酶广泛分布于多种生物体中，在曼氏血吸虫中尤其丰富，但没有确定的生物学功能。在曼氏沙门氏菌中已知的 17 个非 LTR 反转录转座子中，迄今为止没有一个与核酶有关。在这里，我们报告了新的捻线虫变体（T 变体）核酶的鉴定及其在 S. mansoni 非 LTR 逆转录转座中的功能。我们显示 T 变体核酶位于 S. mansoni 基因组中 Perere-3 非 LTR 反转录转座子的 5' 末端。T-变体核酶被证明在体外具有催化活性。在报告构建体中，T 变体显示在体内切割，并且 T 变体的切割足以翻译下游报告基因。我们的分析表明 T 变体和 Perere-3 是一起转录的。目标站点重复（TSD）；目标引发的逆转录 (TPRT) 标记和逆转录转座标记位于 T 变体切割位点附近，表明 T 变体切割已发生在 S。曼索尼。TSD 中的序列异质性表明 Perere-3 逆转录转座不是位点特异性的。TSD 序列有助于末端核酶螺旋（P1 茎）的 5' 端。基于这些结果，我们得出结论，T 变体在 Perere-3 逆转录转座中具有功能性作用。TSD 序列有助于末端核酶螺旋（P1 茎）的 5' 端。基于这些结果，我们得出结论，T 变体在 Perere-3 逆转录转座中具有功能性作用。TSD 序列有助于末端核酶螺旋（P1 茎）的 5' 端。基于这些结果，我们得出结论，T 变体在 Perere-3 逆转录转座中具有功能性作用。