Structure of an RNA silencing complex of the CRISPR-Cas immune system.
Structure of an RNA silencing complex of the CRISPR-Cas immune system.
复制标题
DOI：
10.1016/j.molcel.2013.09.008
复制
发表时间：
2013-10-10
期刊：
影响因子：
16
通讯作者：
Stagg S
中科院分区：
文献类型：
--
作者：
Spilman M;Cocozaki A;Hale C;Shao Y;Ramia N;Terns R;Terns M;Li H;Stagg S
细菌和古细菌CRISPR（重复的规则间隔短回文重复序列）基因座捕获病毒和质粒序列，并使用它们来识别和消除这些入侵者。含有获得的序列的CRISPR（cr）RNA被整合到破坏匹配的入侵核酸的效应复合物中。多组分Cmr效应物复合物切割与crRNA互补的RNA靶标。在这里，我们报告冷冻电子显微镜重建的功能性Cmr复合物与靶RNA结合在1200。成对的Cmr 4和Cmr 5蛋白形成一个螺旋核心，在每一端被不同的四个剩余亚基对不对称地加帽-在保守的5′ crRNA标签序列处的Cmr 2和Cmr 3以及在crRNA的3′端附近的Cmr 1和Cmr 6。RNA靶向Cmr复合物的形状和组织与DNA靶向Cascade复合物惊人相似。我们的研究结果揭示了在非常远的相关CRISPR-Cas复合物中非常保守的结构。
Bacterial and archaeal CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat) loci capture virus and plasmid sequences and use them to recognize and eliminate these invaders. CRISPR (cr)RNAs containing the acquired sequences are incorporated into effector complexes that destroy matching invader nucleic acids. The multi-component Cmr effector complex cleaves RNA targets complementary to the crRNAs. Here we report cryo-electron microscopy reconstruction of a functional Cmr complex bound with a target RNA at ∼12Å. Pairs of the Cmr4 and Cmr5 proteins form a helical core that is asymmetrically capped on each end by distinct pairs of the four remaining subunits – Cmr2 and Cmr3 at the conserved 5′ crRNA tag sequence and Cmr1 and Cmr6 near the 3′ end of the crRNA. The shape and organization of the RNA-targeting Cmr complex is strikingly similar to the DNA-targeting Cascade complex. Our results reveal a remarkably conserved architecture among very distantly related CRISPR-Cas complexes.