加拿大多伦多大学Alan R. Davidson等研究人员合作发现一种能够拆解CRISPR-Cas复合体的抗CRISPR蛋白。该项研究成果于2024年7月3日在线发表在《自然》杂志上。

研究人员对抗CRISPR蛋白AcrIF25进行了表征，并发现它通过拆解完全组装的效应复合物来抑制I-F型CRISPR-Cas系统。AcrIF25与该复合物的主要CRISPR RNA结合组件结合，包括六个Cas7亚基，并将它们从RNA上剥离下来。结构和生化研究表明，AcrIF25从复合物的一端开始，一次去除一个Cas7亚基。值得注意的是，这一过程并不涉及明显的酶促活性。据研究人员所知，AcrIF25是第一个在没有外部能量源的情况下拆解大型稳定大分子复合物的蛋白质。因此，AcrIF25为大分子复合物抑制剂的研究树立了新的范例，可能在生物技术应用中具有重要潜力。

据介绍，在生物系统中，某些时候需要关闭大分子复合物的活动。因此，生物演化出多种多样的蛋白质抑制剂来实现这一目的。这些抑制剂通过多种机制发挥作用，包括空间阻断关键相互作用、酶促修饰关键残基或底物，以及干扰翻译后修饰。抗CRISPR是阻断CRISPR-Cas系统活性的蛋白质家族之一，已描述的抗CRISPR蛋白超过90种，其通过多种机制发挥作用。

附：英文原文

Title: An anti-CRISPR that pulls apart a CRISPR–Cas complex

Author: Trost, Chantel N., Yang, Jing, Garcia, Bianca, Hidalgo-Reyes, Yurima, Fung, Beatrice C. M., Wang, Jiuyu, Lu, Wang-Ting, Maxwell, Karen L., Wang, Yanli, Davidson, Alan R.

Issue&Volume: 2024-07-03

Abstract: In biological systems, the activities of macromolecular complexes must sometimes be turned off. Thus, a wide variety of protein inhibitors has evolved for this purpose. These inhibitors function through diverse mechanisms, including steric blocking of crucial interactions, enzymatic modification of key residues or substrates, and perturbation of post-translational modifications1. Anti-CRISPRs—proteins that block the activity of CRISPR–Cas systems—are one of the largest groups of inhibitors described, with more than 90 families that function through diverse mechanisms2,3,4. Here, we characterize the anti-CRISPR AcrIF25, and we show that it inhibits the type I-F CRISPR–Cas system by pulling apart the fully assembled effector complex. AcrIF25 binds to the predominant CRISPR RNA-binding components of this complex, comprising six Cas7 subunits, and strips them from the RNA. Structural and biochemical studies indicate that AcrIF25 removes one Cas7 subunit at a time, starting at one end of the complex. Notably, this feat is achieved with no apparent enzymatic activity. To our knowledge, AcrIF25 is the first example of a protein that disassembles a large and stable macromolecular complex in the absence of an external energy source. As such, AcrIF25 establishes a paradigm for macromolecular complex inhibitors that may be used for biotechnological applications.

DOI: 10.1038/s41586-024-07642-3

Source: https://www.nature.com/articles/s41586-024-07642-3