Structural organization of a Type III-A CRISPR effector subcomplex determined by X-ray crystallography and cryo-EM
Structural organization of a Type III-A CRISPR effector subcomplex determined by X-ray crystallography and cryo-EM
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DOI：
10.1093/nar/gkz079
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发表时间：
2019-04-23
影响因子：
14.9
通讯作者：
Mondragon, Alfonso
中科院分区：
文献类型：
--
作者：
Dorsey, Bryan W.;Huang, Lei;Mondragon, Alfonso
规则间隔的短回文重复序列（CRISPR）及其相关的Cas蛋白在许多原核生物中提供针对外来核酸的免疫样应答。CRISPR-Cas系统分为不同的类别和类型。1类CRISPR-Cas系统形成多蛋白效应物复合物，其包括用于鉴定用于破坏的靶标的指导RNA（crRNA）。在这里，我们呈现了表皮葡萄球菌III-A型CRISPR亚基Csm 2和Csm 3的晶体结构，以及包括crRNA在内的体内组装效应子复合物的5.2埃分辨率单粒子冷冻电子显微镜（cryo-EM）重建。这些结构有助于阐明III-A型效应复合物的四级结构，并提供关于crRNA结合、靶RNA结合和切割以及效应复合物组装所必需的分子间相互作用的细节。这些结构允许更好地理解III-A型CRISPR效应复合物的组织，并突出显示与其他1类效应复合物的总体相似性和差异。
Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated Cas proteins provide an immune-like response in many prokaryotes against extraneous nucleic acids. CRISPR-Cas systems are classified into different classes and types. Class 1 CRISPR-Cas systems form multi-protein effector complexes that includes a guide RNA (crRNA) used to identify the target for destruction. Here we present crystal structures of Staphylococcus epidermidis Type III-A CRISPR subunits Csm2 and Csm3 and a 5.2 angstrom resolution single-particle cryo-electron microscopy (cryo-EM) reconstruction of an in vivo assembled effector subcomplex including the crRNA. The structures help to clarify the quaternary architecture of Type III-A effector complexes, and provide details on crRNA binding, target RNA binding and cleavage, and intermolecular interactions essential for effector complex assembly. The structures allow a better understanding of the organization of Type III-A CRISPR effector complexes as well as highlighting the overall similarities and differences with other Class 1 effector complexes.