The CRISPR-associated adenosine deaminase Cad1 converts ATP to ITP to provide antiviral immunity

作者：Christian F. Baca, Puja Majumder, James H. Hickling, L. Ye, Marianna Teplova, Sean F. Brady, Dinshaw J. Patel, Luciano A. Marraffini · 发表于：Cell · 年份：2024 · DOI：10.1016/j.cell.2024.10.002 · 被引用次数：22 · 研究领域：CRISPR and Genetic Engineering、Cytomegalovirus and herpesvirus research、Virus-based gene therapy research

Type III CRISPR systems provide immunity against genetic invaders through the production of cyclic oligo-adenylate (cA n ) molecules that activate effector proteins that contain CRISPR-associated Rossman fold (CARF) domains. Here, we characterized the function and structure of an effector in which the CARF domain is fused to an adenosine deaminase domain, CRISPR-associated adenosine deaminase 1 (Cad1). We show that upon binding of cA 4 or cA 6 to its CARF domain, Cad1 converts ATP to ITP, both in vivo and in vitro . Cryoelectron microscopy (cryo-EM) structural studies on full-length Cad1 reveal an hexameric assembly composed of a trimer of dimers, with bound ATP at inter-domain sites required for activity and ATP/ITP within deaminase active sites. Upon synthesis of cA n during phage infection, Cad1 activation leads to a growth arrest of the host that prevents viral propagation. Our findings reveal that CRISPR-Cas systems employ a wide range of molecular mechanisms beyond nucleic acid degradation to provide adaptive immunity in prokaryotes.