Structure of Csx1-cOA4 complex reveals the basis of RNA decay in Type III-B CRISPR-Cas
Structure of Csx1-cOA4 complex reveals the basis of RNA decay in Type III-B CRISPR-Cas
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Csx1-cOA(4) 复合物的结构揭示了 III-B 型 CRISPR-Cas 中 RNA 衰变的基础
DOI：
10.1038/s41467-019-12244-z
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发表时间：
2019-09-20
影响因子：
16.6
通讯作者：
Montoya, Guillermo
中科院分区：
文献类型：
--
作者：
Molina, Rafael;Stella, Stefano;Montoya, Guillermo
III 型 CRISPR-Cas 多亚基复合物可切割 ssRNA 和 ssDNA。这些活性促进环状寡腺苷酸 (cOA) 的产生，从而激活 Csm/Csx 家族相关的 CRISPR-Cas RNA 酶，引发大量 RNA 衰变，从而提供针对遗传入侵者的免疫力。在这里，我们展示了岛硫化叶菌 (Sis) Csx1-cOA(4) 复合物的结构，揭示了其 RNase 活性的变构激活。 SisCsx1 是由二聚体三聚体构建的六聚体。每个二聚体形成一个 coA(4) 结合位点和一个 ssRNA 催化袋。 cOA(4) 在与第二信使结合位点结合后发生构象变化，激活催化口袋中的 ssRNA 降解。激活通过连接 cOA(4) 和催化位点的中间 HTH 结构域以变构方式传递。 RNase 以连续协作方式发挥作用，水解 5'-C-C-3' 中的磷酸二酯键。环核酸酶对 cOA(4) 的降解使 SisCsx1 失活，表明该酶可用于生物技术应用。
Type III CRISPR-Cas multisubunit complexes cleave ssRNA and ssDNA. These activities promote the generation of cyclic oligoadenylate (cOA), which activates associated CRISPR-Cas RNases from the Csm/Csx families, triggering a massive RNA decay to provide immunity from genetic invaders. Here we present the structure of Sulfolobus islandicus (Sis) Csx1-cOA(4) complex revealing the allosteric activation of its RNase activity. SisCsx1 is a hexamer built by a trimer of dimers. Each dimer forms a cOA(4) binding site and a ssRNA catalytic pocket. cOA(4) undergoes a conformational change upon binding in the second messenger binding site activating ssRNA degradation in the catalytic pockets. Activation is transmitted in an allosteric manner through an intermediate HTH domain, which joins the cOA(4) and catalytic sites. The RNase functions in a sequential cooperative fashion, hydrolyzing phosphodiester bonds in 5'-C-C-3'. The degradation of cOA(4) by Ring nucleases deactivates SisCsx1, suggesting that this enzyme could be employed in biotechnological applications.