An anti-CRISPR protein disables type V Cas12a by acetylation
An anti-CRISPR protein disables type V Cas12a by acetylation
复制标题
DOI：
10.1038/s41594-019-0206-1
复制
发表时间：
2019-04-01
影响因子：
16.8
通讯作者：
Huang, Zhiwei
中科院分区：
文献类型：
--
作者：
Dong, Liyong;Guan, Xiaoyu;Huang, Zhiwei
噬菌体使用抗 CRISPR 蛋白来停用 CRISPR-Cas 系统。抗 CRISPR 抑制 I 型和 II 型系统的机制已被阐明。然而，V 型 CRISPR-Cas12a (Cpf1) 系统如何被抗 CRISPR 抑制仍不清楚。在这里，我们鉴定了抗 CRISPR 蛋白 AcrVA5 并报告了它抑制 CRISPR-Cas12a 的机制。我们的结构和生化数据表明，AcrVA5 作为乙酰转移酶来修饰 Moraxella bovoculi (Mb) Cas12a 的 Lys635，这是识别原型间隔子相邻基序所需的残基。 AcrVA5 介导的 MbCas12a 修饰导致双链 DNA (dsDNA) 切割活性完全丧失。相比之下，Lys635Arg 突变使 MbCas12a 对 AcrVA5 的抑制完全不敏感。 AcrVA5 乙酰化 MbCas12a 的冷冻电镜结构表明，Lys635 乙酰化提供了足够的空间位阻，以防止 dsDNA 底物与 Cas 蛋白结合。我们的研究揭示了前所未有的 CRISPR-Cas 抑制机制，并表明噬菌体和细菌之间存在进化军备竞赛。
Phages use anti-CRISPR proteins to deactivate the CRISPR-Cas system. The mechanisms for the inhibition of type I and type II systems by anti-CRISPRs have been elucidated. However, it has remained unknown how the type V CRISPR-Cas12a (Cpf1) system is inhibited by anti-CRISPRs. Here we identify the anti-CRISPR protein AcrVA5 and report the mechanisms by which it inhibits CRISPR-Cas12a. Our structural and biochemical data show that AcrVA5 functions as an acetyltransferase to modify Moraxella bovoculi (Mb) Cas12a at Lys635, a residue that is required for recognition of the protospacer-adjacent motif. The AcrVA5-mediated modification of MbCas12a results in complete loss of double-stranded DNA (dsDNA)-cleavage activity. In contrast, the Lys635Arg mutation renders MbCas12a completely insensitive to inhibition by AcrVA5. A cryo-EM structure of the AcrVA5-acetylated MbCas12a reveals that Lys635 acetylation provides sufficient steric hindrance to prevent dsDNA substrates from binding to the Cas protein. Our study reveals an unprecedented mechanism of CRISPR-Cas inhibition and suggests an evolutionary arms race between phages and bacteria.