Taranenko Dmitry, Kotovskaya Oksana, Kuznedelov Konstantin, Yanovskaya Daria, Demkina Alina, Fardeeva Sofya, Mamontov Viktor, Vierra Kaiya, Burman Nathaniel, Li Dan, Wang Minggui, Wiedenheft Blake, Severinov Konstantin, Semenova Ekaterina, Isaev Artem
Skolkovo Institute of Science and Technology, Moscow, Russia.
Waksman Institute for Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
bioRxiv. 2025 May 10:2025.05.07.652737. doi: 10.1101/2025.05.07.652737.
CRISPR-Cas adaptive immunity systems provide defense against mobile genetic elements and are often countered by diverse anti-CRISPR (Acr) proteins. The Type IE CRISPR-Cas of K12 has been a model for structural and functional studies and is a part of the species' core genome. However, this system is transcriptionally silent, which has fueled questions about its true biological function. To clarify the role of this system in defense, we carried out a census of Acr proteins found in and identified AcrIE9 as a potent inhibitor of the K12 Type IE CRISPR-Cas system. While sharing little sequence identity, AcrIE9 proteins from and both interact with the Cas7 subunit of the Cascade complex, thus preventing its binding to DNA. We further show that AcrIE9 is genetically linked to AcrIE10, forming the most widespread anti-CRISPR cluster in and this module often co-occurs with a novel HTH-like protein with unusual architecture.
CRISPR-Cas适应性免疫系统可抵御移动遗传元件，且常常会受到多种抗CRISPR（Acr）蛋白的对抗。K12的I-E型CRISPR-Cas一直是结构和功能研究的模型，并且是该物种核心基因组的一部分。然而，该系统在转录上是沉默的，这引发了关于其真正生物学功能的疑问。为了阐明该系统在防御中的作用，我们对在[具体物种]中发现的Acr蛋白进行了普查，并鉴定出AcrIE9是K12 I-E型CRISPR-Cas系统的有效抑制剂。虽然序列同一性很低，但来自[不同来源]的AcrIE9蛋白均与Cascade复合物的Cas7亚基相互作用，从而阻止其与DNA结合。我们进一步表明，AcrIE9在基因上与AcrIE10相关联，在[具体物种]中形成了最广泛的抗CRISPR簇，并且该模块经常与一种具有异常结构的新型HTH样蛋白共同出现。
