Structure Studies of the CRISPR-Csm Complex Reveal Mechanism of Co-transcriptional Interference
Structure Studies of the CRISPR-Csm Complex Reveal Mechanism of Co-transcriptional Interference
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CRISPR-Csm复合物的结构研究揭示共转录干扰机制
DOI：
10.1016/j.cell.2018.10.052
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发表时间：
2019
期刊：
影响因子：
64.5
通讯作者：
Wang Yanli
中科院分区：
文献类型：
--
作者：
You Lilan;Ma Jun;Wang Jiuyu;Artamonova Daria;Wang Min;Liu Liang;Xiang Hua;Severinov Konstantin;Zhang Xinzheng;Wang Yanli
Csm是一种III-A型CRISPR-Cas干扰复合物，是一种CRISPR RNA（crRNA）引导的RNA酶，也具有靶RNA依赖性DNA酶和环寡腺苷酸（cOA）合成酶活性。然而，允许靶RNA结合依赖性激活DNA切割和cOA生成的结构特征仍然未知。在这里，我们报告了与crRNA复合的Csm的结构以及同源或非同源靶RNA结合的Csm复合物的结构。我们发现，根据与crRNA的5′标签的互补性，靶RNA的3′反标签区域结合在Csm复合物的两个不同位点。重要的是，同源靶RNA的非互补反标签区与Csm 1之间的相互作用诱导Csm 1亚基的构象变化，其变构激活DNA切割和cOA生成。总之，我们的结构研究为crRNA介导的序列特异性RNA切割、RNA靶依赖性非特异性DNA切割和cOA生成所需的机制过程提供了重要见解。
Csm, a type III-A CRISPR-Cas interference complex, is a CRISPR RNA (crRNA)-guided RNase that also possesses target RNA-dependent DNase and cyclic oligoadenylate (cOA) synthetase activities. However, the structural features allowing target RNA-binding-dependent activation of DNA cleavage and cOA generation remain unknown. Here, we report the structure of Csm in complex with crRNA together with structures of cognate or non-cognate target RNA bound Csm complexes. We show that depending on complementarity with the 5′ tag of crRNA, the 3′ anti-tag region of target RNA binds at two distinct sites of the Csm complex. Importantly, the interaction between the non-complementary anti-tag region of cognate target RNA and Csm1 induces a conformational change at the Csm1 subunit that allosterically activates DNA cleavage and cOA generation. Together, our structural studies provide crucial insights into the mechanistic processes required for crRNA-meditated sequence-specific RNA cleavage, RNA target-dependent non-specific DNA cleavage, and cOA generation.