Structure of AcrVIA2 and its binding mechanism to CRISPR-Cas13a
Structure of AcrVIA2 and its binding mechanism to CRISPR-Cas13a
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AcrVIA2的结构及其与CRISPR-Cas13a的结合机制
DOI：
10.1016/j.bbrc.2022.04.091
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发表时间：
2022
影响因子：
3.1
通讯作者：
Xiaojie Yan
中科院分区：
文献类型：
--
作者：
Guangyong Song;Xuzichao Li;Zhangzhao Wang;Cheng Dong;Xiangyang Xie;Xiaojie Yan
噬菌体和非噬菌体衍生的细菌已经进化出许多抗crispr蛋白（Acrs）来逃避原核生物的适应性免疫系统。因此，Acrs可以作为CRISPR系统编辑基因的调控工具。最近，一种非噬菌体衍生的AcrVIA2被鉴定为一种抑制剂，通过与Cas13a结合，在体外阻断Cas13a的编辑活性。在这里，我们以2.59 Å的分辨率解算了AcrVIA2的晶体结构，证实了AcrVIA2可以结合LshCas13a的Helical-I结构域。结构分析表明，AcrVIA2二聚体β3-β3发夹形成的v型酸性槽是介导AcrVIA2与Helical-I结构域相互作用的关键区域。此外，我们还发现AcrVIA2的Asp37在v型酸性槽的功能中起着至关重要的作用，并且AcrVIA2的功能二聚体构象是通过一个单体的Tyr41与Glu35和另一个单体的Asp37之间形成的氢键来稳定的。这些数据拓展了目前对Acrs和Cas蛋白之间多种相互作用机制的认识，也为CRISPR-Cas13a调控工具的开发提供了新的思路。
Phages and non-phage derived bacteria have evolved manyanti-CRISPR proteins (Acrs) to escape the adaptive immune system of prokaryotes. Thus Acrs can be applied as a regulatory tool for gene edition by CRISPR system. Recently, a non-phage derived AcrVIA2 has been identified as an inhibitor that blocks the editing activity of Cas13a in vitro by binding to Cas13a. Here, we solved the crystal structure of AcrVIA2 at a resolution of 2.59 Å and confirmed that AcrVIA2 can bind to Helical-I domain in LshCas13a. Structural analysis show that the V-shaped acidic groove formed by β3-β3 hairpin of AcrVIA2 dimer is the key region that mediates the interaction between AcrVIA2 and Helical-I domain. In addition, we also reveal that Asp37 of AcrVIA2 plays an essential role in the functioning of the V-shaped acidic groove, and the functional dimer conformation of AcrVIA2 is stabilized by hydrogen bonds formed between Tyr41 of one monomer with Glu35 and Asp37 of the other monomer. These data expand the current understanding of the diverse interaction mechanisms between Acrs and Cas proteins, and also provide new ideas for the development of CRISPR-Cas13a regulatory tool.