通过PCNA结合的FEN1和RNaseH2介导的Okazaki碎片成熟的结构洞察力
Yuhui Tian1, Ningning Li1,2, Qing Li3
1State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
The EMBO journal
|November 23, 2024
概括
增殖细胞核抗原 (PCNA) 协调DNA复制. 新的冷EM结构揭示了PCNA相关酶FEN1和RNaseH2在Okazaki碎片成熟过程中如何相互作用,澄清了酶调节.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- 增殖细胞核抗原 (PCNA) 对于DNA代谢至关重要,与参与DNA复制的多种酶相互作用.
- 在Okazaki碎片成熟过程中,PCNA结合蛋白的精确协调和功能相互作用仍然不完全理解.
研究的目的:
- 阐明在Okazaki碎片成熟过程中PCNA相关酶的结构基础和功能机制.
- 调查FEN1和RNaseH2与PCNA复合的时间关系和构造动态.
主要方法:
- 开发一种从原生染色质中净化内源性PCNA含有复合物的策略.
- 使用冷电子显微镜 (cryo-EM) 净化复合物的结构特征.
- 酶基质相互作用和构造变化的分析.
主要成果:
- 解决了两个不同的结构类,PCNA-FEN1和PCNA-FEN1-RNaseH2复合体,提供了原料去除步骤的快照.
- 来自FEN1的产品释放被确定为过程中的速度限制步骤.
- 在PCNA上FEN1和RNaseH2的符合性变化调节基质DNA曲,表明相互调节.
- PCNA-FEN1-RNaseH2结构支持PCNA的"工具带"模型,并表明RNaseH2可能增强FEN1活性.
结论:
- PCNA充当了支架,促进了FEN1和RNaseH2在Okazaki碎片处理中的协调行动.
- 在PCNA上,酶动力学会影响DNA构造,从而实现酶间调节.
- RNaseH2可能在促进FEN1的5'-flap裂变活性方面具有未被描述的作用.
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