DNA inversion is a type of site-specific recombination system that plays an important role in the generation of genetic diversity and phenotypic adaptation by programmed rearrangements in bacteria. However, no such inversion system exhibiting a strong directionality bias has been identified or developed in eukaryotes yet. Here, using directed evolution of Rci recombinase, a tyrosine recombinase from a bacterial DNA inversion system, we identified a mutant Rci8 with a ratio of inversion/deletion up to ∼4320 in yeast. Based on Rci8 recombinase and sfxa101 sites, we have established a DNA inversion system in yeast and mammalian cells, enabling specificity for DNA inversions between inverted sites over deletions between directly repeated sites. Our results validated that the reversible DNA inversion system can act as an on/off transcriptional switch. Moreover, we demonstrate that the inversion system can also work on linear chromosomes. The eukaryotic DNA inversion system would provide a new tool for fields of genetic circuits, cellular barcoding, and synthetic genomes.

中文翻译：

---

通过实验室进化建立的真核生物 DNA 倒置系统

DNA倒位是一种位点特异性重组系统，它在细菌中通过程序性重排产生遗传多样性和表型适应中起重要作用。然而，尚未在真核生物中发现或开发出这种表现出强烈方向性偏差的反转系统。在这里，使用 Rci 重组酶（一种来自细菌 DNA 倒位系统的酪氨酸重组酶）的定向进化，我们鉴定了一种突变体 Rci8，其在酵母中的倒位/缺失比率高达 ∼4320。基于 Rci8 重组酶和sfxa101位点，我们已经在酵母和哺乳动物细胞中建立了 DNA 倒位系统，使倒位位点之间的 DNA 倒位与直接重复位点之间的缺失具有特异性。我们的结果验证了可逆的 DNA 反转系统可以作为一个开/关转录开关。此外，我们证明倒位系统也可以在线性染色体上工作。真核 DNA 倒置系统将为遗传回路、细胞条形码和合成基因组领域提供新工具。