High-complexity of DNA double-strand breaks is key for alternative end-joining choice

• Published in: Communications biology Vol. 7; no. 1; pp. 936 - 9
• Main Authors: Hou, Zhiyang, Yu, Tianxiang, Yi, Qiyi, Du, Yan, Zhou, Libin, Zhao, Ye, Wu, Yuejin, Wu, Lijun, Wang, Ting, Bian, Po
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.08.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 38/70; 631/208/737/211; 631/337/1427; Biomedical and Life Sciences; DNA Breaks, Double-Stranded; DNA damage; DNA End-Joining Repair; DNA repair; Double-strand break repair; Escherichia coli - genetics; Escherichia coli - metabolism; Genomic instability; Homologous Recombination; Homology; Ionizing radiation; Life Sciences; Non-homologous end joining; Yeast
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-024-06640-5

The repair of DNA double-strand breaks (DSBs) through alternative non-homologous end-joining (alt-NHEJ) pathway significantly contributes to genetic instability. However, the mechanism governing alt-NHEJ pathway choice, particularly its association with DSB complexity, remains elusive due to the absence of a suitable reporter system. In this study, we established a unique Escherichia coli reporter system for detecting complex DSB-initiated alternative end-joining (A-EJ), an alt-NHEJ-like pathway. By utilizing various types of ionizing radiation to generate DSBs with varying degrees of complexity, we discovered that high complexity of DSBs might be a determinant for A-EJ choice. To facilitate efficient repair of high-complexity DSBs, A-EJ employs distinct molecular patterns such as longer micro-homologous junctions and non-templated nucleotide addition. Furthermore, the A-EJ choice is modulated by the degree of homology near DSB loci, competing with homologous recombination machinery. These findings further enhance the understanding of A-EJ/alt-NHEJ pathway choice. The identification of the dependence of alternative end-joining mechanism on the complexity of DNA double-strands breaks (DSBs) and the homology of DSB loci advances our comprehension regarding pathway choice for repairing DNA damage.