美国麻省理工学院Jonathan S. Gootenberg、Omar O. Abudayyeh等研究人员合作开发出新型RNA编辑系统。相关论文于2021年9月6日在线发表在《自然》杂志上。
研究人员表明III-E亚型效应器Cas7-11是1类CRISPR-Cas系统中的一个单蛋白效应器，其源于一个假定的Cas11结构域和多个Cas7亚单位的融合，这些亚单位来自III-D亚型。当来自Desulfonema ishimotonii的Cas7-11（DiCas7-11）在大肠杆菌中表达时，对mRNA和噬菌体具有实质性的RNA干扰效果。与许多第2类效应器相似（这在第1类系统中是独一无二的），DiCas7-11将pre-CRISPR RNA加工为成熟的CRISPR RNA（crRNA），并在靶标:间隔物所定义的位置切割RNA，并没有可检测的非特异性活性。
研究人员设计了Cas7-11用于哺乳动物细胞中的RNA敲除和编辑。结果表明，Cas7-11对细胞活力没有影响，而其他RNA靶向工具（如短发夹RNA和Cas13）显示出大量的细胞毒性。这项研究说明了单蛋白效应器从多亚基1类效应器复合物的演变，并扩大了人们对CRISPR系统多样性的理解。Cas7-11为新的可编程RNA靶向工具提供了基础，并不具有附带的活性和细胞毒性。
据介绍，CRISPR-Cas干扰是由Cas效应核酸酶介导的，这些核酸酶要么是多亚单位复合物的组成部分（第1类CRISPR-Cas系统），要么是单一蛋白的结构域（第2类系统）。
附：英文原文
Title: Programmable RNA targeting with the single-protein CRISPR effector Cas7-11
Author: zcan, Ahsen, Krajeski, Rohan, Ioannidi, Eleonora, Lee, Brennan, Gardner, Apolonia, Makarova, Kira S., Koonin, Eugene V., Abudayyeh, Omar O., Gootenberg, Jonathan S.
Issue&Volume: 2021-09-06
Abstract: CRISPR–Cas interference is mediated by Cas effector nucleases that are either components of multisubunit complexes—in class1 CRISPR–Cas systems—or domains of a single protein—in class2 systems1,2,3. Here we show that the subtypeIII-E effector Cas7-11 is a single-protein effector in the class1 CRISPR–Cas systems originating from the fusion of a putative Cas11 domain and multiple Cas7 subunits that are derived from subtypeIII-D. Cas7-11 from Desulfonema ishimotonii (DiCas7-11), when expressed in Escherichia coli, has substantial RNA interference effectivity against mRNAs and bacteriophages. Similar to many class2 effectors—and unique among class1 systems—DiCas7-11 processes pre-CRISPR RNA into mature CRISPR RNA (crRNA) and cleaves RNA at positions defined by the target:spacer duplex, without detectable non-specific activity. We engineered Cas7-11 for RNA knockdown and editing in mammalian cells. We show that Cas7-11 has no effects on cell viability, whereas other RNA-targeting tools (such as short hairpin RNAs and Cas13) show substantial cell toxicity4,5. This study illustrates the evolution of a single-protein effector from multisubunit class1 effector complexes, expanding our understanding of the diversity of CRISPR systems. Cas7-11 provides the basis for new programmable RNA-targeting tools that are free of collateral activity and cell toxicity.
DOI: 10.1038/s41586-021-03886-5
Source: https://www.nature.com/articles/s41586-021-03886-5
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html
本期文章：《自然》：Online/在线发表
