据研究人员介绍，CRISPR-Cas系统通过RNA引导的核酸酶活性在原核生物中对外来遗传元件提供适应性免疫反应。最近，在与CRISPR系统的遗传关联中发现了更多具有非核酸酶功能的基因，表明可能存在其他RNA引导的非核酸酶。一个这样的基因编码TPR-CHAT蛋白酶Csx29，它与CRISPR效应器Cas7-11相关。
研究人员证明了这种CRISPR相关蛋白酶（CASP）对Σ因子抑制剂表现出可编程的RNA激活的内肽酶活性，从而调节转录反应。一种活跃的、底物结合的CASP复合物的冷冻电镜显示了一种异构激活机制，该机制在靶标RNA结合时重组Csx29的催化残基。这项工作揭示了自然界中的一种RNA引导功能，它可以被用于体外和人类细胞中的RNA感应应用。
附：英文原文
Title: RNA-activated protein cleavage with a CRISPR-associated endopeptidase
Author: Jonathan Strecker, F. Esra Demircioglu, David Li, Guilhem Faure, Max E. Wilkinson, Jonathan S. Gootenberg, Omar O. Abudayyeh, Hiroshi Nishimasu, Rhiannon K. Macrae, Feng Zhang
Issue&Volume: 2022-11-03
Abstract: CRISPR-Cas systems provide adaptive immune responses in prokaryotes against foreign genetic elements through RNA-guided nuclease activity. Recently, additional genes with non-nuclease functions have been found in genetic association with CRISPR systems, suggesting there may be other RNA-guided non-nucleolytic enzymes. One such gene encodes the TPR-CHAT protease Csx29, which is associated with the CRISPR effector Cas7-11. Here, we demonstrate that this CRISPR-associated protease (CASP) exhibits programmable RNA-activated endopeptidase activity against a sigma factor inhibitor to regulate a transcriptional response. Cryo–electron microscopy of an active and substrate-bound CASP complex reveals an allosteric activation mechanism that reorganizes Csx29 catalytic residues upon target RNA binding. This work reveals an RNA-guided function in nature which can be leveraged for RNA sensing applications in vitro and in human cells.
DOI: add7450
Source: https://www.science.org/doi/10.1126/science.add7450