Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China.
Nat Rev Mol Cell Biol. 2021 Aug;22(8):563-579. doi: 10.1038/s41580-021-00371-9. Epub 2021 Jun 4.
CRISPR loci and Cas proteins provide adaptive immunity in prokaryotes against invading bacteriophages and plasmids. In response, bacteriophages have evolved a broad spectrum of anti-CRISPR proteins (anti-CRISPRs) to counteract and overcome this immunity pathway. Numerous anti-CRISPRs have been identified to date, which suppress single-subunit Cas effectors (in CRISPR class 2, type II, V and VI systems) and multisubunit Cascade effectors (in CRISPR class 1, type I and III systems). Crystallography and cryo-electron microscopy structural studies of anti-CRISPRs bound to effector complexes, complemented by functional experiments in vitro and in vivo, have identified four major CRISPR-Cas suppression mechanisms: inhibition of CRISPR-Cas complex assembly, blocking of target binding, prevention of target cleavage, and degradation of cyclic oligonucleotide signalling molecules. In this Review, we discuss novel mechanistic insights into anti-CRISPR function that have emerged from X-ray crystallography and cryo-electron microscopy studies, and how these structures in combination with function studies provide valuable tools for the ever-growing CRISPR-Cas biotechnology toolbox, to be used for precise and robust genome editing and other applications.
CRISPR 基因座和 Cas 蛋白为原核生物提供了针对入侵噬菌体和质粒的适应性免疫。作为回应，噬菌体进化出了广泛的抗 CRISPR 蛋白（抗 CRISPRs）来对抗和克服这种免疫途径。迄今为止，已经鉴定出许多抗 CRISPRs，它们可以抑制单亚基 Cas 效应物（在 CRISPR 类 2、2 型、V 和 VI 系统中）和多亚基级联效应物（在 CRISPR 类 1、I 和 III 系统中）。结合体外和体内功能实验，对与效应物复合物结合的抗 CRISPRs 的晶体学和低温电子显微镜结构研究，确定了四个主要的 CRISPR-Cas 抑制机制：抑制 CRISPR-Cas 复合物组装、阻止靶结合、防止靶切割和降解环状寡核苷酸信号分子。在这篇综述中，我们讨论了 X 射线晶体学和低温电子显微镜研究中出现的抗 CRISPR 功能的新机制见解，以及这些结构如何与功能研究一起为不断增长的 CRISPR-Cas 生物技术工具箱提供有价值的工具，用于精确和稳健的基因组编辑和其他应用。
