据介绍，TnpB核酸酶是CRISPR-Cas12的演化前体，广泛存在于生命的各个领域。IS605家族TnpB同源物在细菌中起着可编程RNA引导的归巢内切酶的作用，通过DNA双链断裂刺激的同源重组来驱动转座子的维持。
研究人员揭示了IS607家族元件转座生命周期的分子机制，这些元件也编码I族内含子。研究人员确定了肉毒梭菌候选“IStron”的特定特征，使该元件能够仔细控制剪接产物与功能导向RNA的相对水平。研究结果表明，IStron转录本演化出了一种平衡竞争和互斥活动的能力，这些活动促进了自私转座子的传播，同时限制了宿主的不利适应成本。
总之，这项工作突出了转座子编码的非编码RNA在多功能应用中的分子创新。
附：英文原文
Title: Antagonistic conflict between transposon-encoded introns and guide RNAs
Author: Rimant edaveinyt, Chance Meers, Hoang C. Le, Edan E. Mortman, Stephen Tang, George D. Lampe, Sanjana R. Pesari, Diego R. Gelsinger, Tanner Wiegand, Samuel H. Sternberg
Issue&Volume: 2024-07-12
Abstract: TnpB nucleases represent the evolutionary precursors to CRISPR-Cas12 and are widespread in all domains of life. IS605-family TnpB homologs function as programmable RNA-guided homing endonucleases in bacteria, driving transposon maintenance through DNA double-strand break–stimulated homologous recombination. In this work, we uncovered molecular mechanisms of the transposition life cycle of IS607-family elements that, notably, also encode group I introns. We identified specific features for a candidate “IStron” from Clostridium botulinum that allow the element to carefully control the relative levels of spliced products versus functional guide RNAs. Our results suggest that IStron transcripts evolved an ability to balance competing and mutually exclusive activities that promote selfish transposon spread while limiting adverse fitness costs on the host. Collectively, this work highlights molecular innovation in the multifunctional utility of transposon-encoded noncoding RNAs.
DOI: adm8189
Source: https://www.science.org/doi/10.1126/science.adm8189