A diRNA–protein scaffold module mediates SMC5/6 recruitment in plant DNA repair

作者：Jieming Jiang, Xiaolin Ou, Danlu Han, Zhipeng He, Song Liu, Ning Mao, Zhonghui Zhang, Changlian Peng, Jianbin Lai, Chengwei Yang · 发表于：The Plant Cell · 年份：2022 · DOI：10.1093/plcell/koac191 · 被引用次数：20 · 研究领域：DNA Repair Mechanisms、RNA Research and Splicing、Genomics and Chromatin Dynamics

In eukaryotes, the STRUCTURAL MAINTENANCE OF CHROMOSOME 5/6 (SMC5/6) complex is critical to maintaining chromosomal structures around double-strand breaks (DSBs) in DNA damage repair. However, the recruitment mechanism of this conserved complex at DSBs remains unclear. In this study, using Arabidopsis thaliana as a model, we found that SMC5/6 localization at DSBs is dependent on the protein scaffold containing INVOLVED IN DE NOVO 2 (IDN2), CELL DIVISION CYCLE 5 (CDC5), and ALTERATION/DEFICIENCY IN ACTIVATION 2B (ADA2b), whose recruitment is further mediated by DNA-damage-induced RNAs (diRNAs) generated from DNA regions around DSBs. The physical interactions of protein components including SMC5-ADA2b, ADA2b-CDC5, and CDC5-IDN2 result in formation of the protein scaffold. Further analysis indicated that the DSB localization of IDN2 requires its RNA-binding activity and ARGONAUTE 2 (AGO2), indicating a role for the AGO2-diRNA complex in this process. Given that most of the components in the scaffold are conserved, the mechanism presented here, which connects SMC5/6 recruitment and small RNAs, will improve our understanding of DNA repair mechanisms in eukaryotes.