Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.
Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, USA.
Nat Chem Biol. 2021 Apr;17(4):387-393. doi: 10.1038/s41589-020-00721-2. Epub 2021 Jan 25.
Cas12g, the type V-G CRISPR-Cas effector, is an RNA-guided ribonuclease that targets single-stranded RNA substrate. The CRISPR-Cas12g system offers a potential platform for transcriptome engineering and diagnostic applications. We determined the structures of Cas12g-guide RNA complexes in the absence and presence of target RNA by cryo-EM to a resolution of 3.1 Å and 4.8 Å, respectively. Cas12g adopts a bilobed structure with miniature REC2 and Nuc domains, whereas the guide RNAs fold into a flipped 'F' shape, which is primarily recognized by the REC lobe. Target RNA and the CRISPR RNA (crRNA) guide form a duplex that inserts into the central cavity between the REC and NUC lobes, inducing conformational changes in both lobes to activate Cas12g. The structural insights would facilitate the development of Cas12g-based applications.
Cas12g，一种 V-G 型 CRISPR-Cas 效应物，是一种靶向单链 RNA 底物的 RNA 指导的核糖核酸酶。CRISPR-Cas12g 系统为转录组工程和诊断应用提供了一个潜在的平台。我们通过 cryo-EM 分别确定了 Cas12g-引导 RNA 复合物在无靶 RNA 和有靶 RNA 存在下的结构，分辨率分别为 3.1Å 和 4.8Å。Cas12g 采用具有微型 REC2 和 Nuc 结构域的双叶结构，而引导 RNA 折叠成翻转的“F”形，主要由 REC 叶识别。靶 RNA 和 CRISPR RNA（crRNA）引导形成双链体，插入 REC 和 NUC 叶之间的中央腔中，诱导两个叶的构象变化，从而激活 Cas12g。这些结构见解将有助于 Cas12g 为基础的应用的发展。
