A programmable type of CRISPR system CRISPR-Cas9 systems have been causing a revolution in biology. Harrington et al. describe the discovery and technological implementation of an additional type of CRISPR system based on an extracompact effector protein, Cas14. Metagenomics data, particularly from uncultivated samples, uncovered the CRISPR-Cas14 systems containing all the components necessary for adaptive immunity in prokaryotes. At half the size of class 2 CRISPR effectors, Cas14 appears to target single-stranded DNA without class 2 sequence restrictions. By leveraging this activity, a fast and high-fidelity nucleic acid detection system enabled detection of single-nucleotide polymorphisms. Science, this issue p. 839 Identification, characterization, and technological implementation of additional archaea-derived CRISPR-Cas14 systems are described. CRISPR-Cas systems provide microbes with adaptive immunity to infectious nucleic acids and are widely employed as genome editing tools. These tools use RNA-guided Cas proteins whose large size (950 to 1400 amino acids) has been considered essential to their specific DNA- or RNA-targeting activities. Here we present a set of CRISPR-Cas systems from uncultivated archaea that contain Cas14, a family of exceptionally compact RNA-guided nucleases (400 to 700 amino acids). Despite their small size, Cas14 proteins are capable of targeted single-stranded DNA (ssDNA) cleavage without restrictive sequence requirements. Moreover, target recognition by Cas14 triggers nonspecific cutting of ssDNA molecules, an activity that enables high-fidelity single-nucleotide polymorphism genotyping (Cas14-DETECTR). Metagenomic data show that multiple CRISPR-Cas14 systems evolved independently and suggest a potential evolutionary origin of single-effector CRISPR-based adaptive immunity.

中文翻译：

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通过微型 CRISPR-Cas14 酶进行程序性 DNA 破坏

可编程类型的 CRISPR 系统 CRISPR-Cas9 系统正在引发生物学领域的一场革命。哈林顿等人。描述了基于超紧凑效应蛋白 Cas14 的另一种 CRISPR 系统的发现和技术实施。宏基因组数据，特别是来自未培养样本的数据，揭示了 CRISPR-Cas14 系统包含原核生物适应性免疫所需的所有组件。Cas14 的大小只有 2 类 CRISPR 效应子的一半，似乎可以靶向单链 DNA，而不受 2 类序列限制。通过利用这一活性，快速、高保真度的核酸检测系统能够检测单核苷酸多态性。科学，本期第 14 页。第839章 描述了其他古细菌衍生的 CRISPR-Cas14 系统的鉴定、表征和技术实施。CRISPR-Cas系统为微生物提供了对感染性核酸的适应性免疫，并被广泛用作基因组编辑工具。这些工具使用 RNA 引导的 Cas 蛋白，其大尺寸（950 至 1400 个氨基酸）被认为对其特定 DNA 或 RNA 靶向活动至关重要。在这里，我们展示了一套来自未培养古细菌的 CRISPR-Cas 系统，其中包含 Cas14，这是一个极其紧凑的 RNA 引导核酸酶家族（400 至 700 个氨基酸）。尽管 Cas14 蛋白尺寸较小，但它能够靶向单链 DNA (ssDNA) 切割，而无需限制性序列要求。此外，Cas14 的目标识别会触发 ssDNA 分子的非特异性切割，这种活性可实现高保真单核苷酸多态性基因分型 (Cas14-DETECTR)。宏基因组数据显示多个 CRISPR-Cas14 系统独立进化，并提示基于单效应 CRISPR 的适应性免疫的潜在进化起源。