Xu Ying, Xu Lingyi, Qin Chen, Wang Liangyan, Guo Jiangtao, Hua Yuejin, Zhao Ye
MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou, China.
Department of Biophysics, Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China.
Structure. 2022 Sep 1;30(9):1298-1306.e3. doi: 10.1016/j.str.2022.06.005. Epub 2022 Jul 15.
DNA end resection mediated by the coordinated action of nuclease and helicase is a crucial step in initiating homologous recombination. The end-resection apparatus NurA nuclease and HerA helicase are present in both archaea and bacteria. Here, we report the cryo-electron microscopy structure of a bacterial HerA-NurA complex from Deinococcus radiodurans. The structure reveals a barrel-like hexameric HerA and a distinctive NurA dimer subcomplex, which has a unique extended N-terminal region (ENR) involved in bacterial NurA dimerization and activation. In addition to the long protruding linking loop and the C-terminal α helix of NurA, the flexible ENR is close to the HerA-NurA interface and divides the central channel of the DrNurA dimer into two halves, suggesting a possible mechanism of DNA end processing. In summary, this work provides new insights into the structure, assembly, and activation mechanisms of bacterial DNA end resection mediated by a minimal end-resection apparatus.
由核酸酶和解旋酶协同作用介导的DNA末端切除是启动同源重组的关键步骤。末端切除装置NurA核酸酶和HerA解旋酶存在于古细菌和细菌中。在这里，我们报告了来自耐辐射球菌的细菌HerA-NurA复合物的冷冻电子显微镜结构。该结构揭示了一个桶状六聚体HerA和一个独特的NurA二聚体亚复合物，其具有参与细菌NurA二聚化和激活的独特延伸N端区域（ENR）。除了NurA的长突出连接环和C端α螺旋外，柔性ENR靠近HerA-NurA界面，并将DrNurA二聚体的中央通道分成两半，提示了一种可能的DNA末端加工机制。总之，这项工作为最小末端切除装置介导的细菌DNA末端切除的结构、组装和激活机制提供了新的见解。
