Structural Basis for pri-miRNA Recognition by Drosha
Structural Basis for pri-miRNA Recognition by Drosha
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Drosha 识别 pri-miRNA 的结构基础
DOI：
10.1016/j.molcel.2020.02.024
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发表时间：
2020-05-07
期刊：
影响因子：
16
通讯作者：
Xu, Rui-Ming
中科院分区：
文献类型：
--
作者：
Jin, Wenxing;Wang, Jia;Xu, Rui-Ming
miRNA生物合成的起始和关键步骤涉及微处理器对细胞核中pri-miRNA的处理。一个重要但尚未完全理解的问题是微处理器的催化亚基Drosha如何结合pri-miRNAs并正确指定切割位点。在这里，我们报告了Drosha-DGCR 8复合物的冷冻电子显微镜结构，有和没有pri-miRNA。RNA结合的结构提供了pri-miRNA三级结构的直接可视化，并显示延伸的PAZ结构域中的螺旋发夹和Drosha的RNase IIIa结构域中的移动的碱性（MB）螺旋协调识别RNA的单链到双链连接，而dsRNA结合结构域与RNA茎广泛接触。此外，无RNA的结构揭示了PAZ螺旋发夹的自抑制构象。这些发现为微处理器的催化组分对pri-miRNA切割位点的选择和控制pri-miRNA识别的构象动力学提供了机理上的见解。
A commencing and critical step in miRNA biogenesis involves processing of pri-miRNAs in the nucleus by Microprocessor. An important, but not completely understood, question is how Drosha, the catalytic subunit of Microprocessor, binds pri-miRNAs and correctly specifies cleavage sites. Here we report the cryoelectron microscopy structures of the Drosha-DGCR8 complex with and without a pri-miRNA. The RNA-bound structure provides direct visualization of the tertiary structure of pri-miRNA and shows that a helix hairpin in the extended PAZ domain and the mobile basic (MB) helix in the RNase Illa domain of Drosha coordinate to recognize the single-stranded to double-stranded junction of RNA, whereas the dsRNA binding domain makes extensive contacts with the RNA stem. Furthermore, the RNA-free structure reveals an autoinhibitory conformation of the PAZ helix hairpin. These findings provide mechanistic insights into pri-miRNA cleavage site selection and conformational dynamics governing pri-miRNA recognition by the catalytic component of Microprocessor.