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.
摘要：
TnpB核酸酶代表CRISPR-Cas12的进化前体,并且广泛存在于生命的所有领域中。IS605家族TnpB同源物在细菌中作为可编程RNA指导的归巢核酸内切酶，通过DNA双链断裂刺激的同源重组驱动转座子维持。在这项工作中,我们发现了IS607家族元件转座生命周期的分子机制，特别是,还编码I组内含子。我们确定了来自肉毒梭菌的候选“IStron”的特定特征，该特征允许该元素仔细控制剪接产物与功能指导RNA的相对水平。我们的结果表明，ISron转录本进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的转座子传播，同时限制了宿主的不利适应性成本。总的来说，这项工作突出了在转座子编码的非编码RNA的多功能效用方面的分子创新.
