Asgard 古菌中独特的 CRISPR-Cas 相关系统和 Cas1 同源物的空前多样性。
Unprecedented Diversity of Unique CRISPR-Cas-Related Systems and Cas1 Homologs in Asgard Archaea.
机构信息
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA.
Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, P.R. China.
出版信息
CRISPR J. 2020 Jun;3(3):156-163. doi: 10.1089/crispr.2020.0012.
The principal function of archaeal and bacterial CRISPR-Cas systems is antivirus adaptive immunity. However, recent genome analyses identified a variety of derived CRISPR-Cas variants at least some of which appear to perform different functions. Here, we describe a unique repertoire of CRISPR-Cas-related systems that we discovered by searching archaeal metagenome-assemble genomes of the Asgard superphylum. Several of these variants contain extremely diverged homologs of Cas1, the integrase involved in CRISPR adaptation as well as casposon transposition. Strikingly, the diversity of Cas1 in Asgard archaea alone is greater than that detected so far among the rest of archaea and bacteria. The Asgard CRISPR-Cas derivatives also encode distinct forms of Cas4, Cas5, and Cas7 proteins, and/or additional nucleases. Some of these systems are predicted to perform defense functions, but possibly not programmable ones, whereas others are likely to represent previously unknown mobile genetic elements.
古菌和细菌 CRISPR-Cas 系统的主要功能是抗病毒适应性免疫。然而，最近的基因组分析在至少一些衍生的 CRISPR-Cas 变体中识别出各种不同的功能。在这里，我们通过搜索古菌门的宏基因组组装基因组，描述了一组独特的 CRISPR-Cas 相关系统。其中一些变体包含 Cas1 的极度分化同源物，Cas1 是参与 CRISPR 适应性的整合酶以及 casposon 转座。引人注目的是，古菌门中 Cas1 的多样性比迄今为止在其余古菌和细菌中检测到的多样性还要大。这些古菌门 CRISPR-Cas 衍生物还编码不同形式的 Cas4、Cas5 和 Cas7 蛋白和/或其他核酸酶。其中一些系统被预测具有防御功能，但可能不是可编程的，而其他系统可能代表以前未知的移动遗传元件。
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