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Nature Communications Jun 2020Bacteria have evolved sophisticated adaptive immune systems, called CRISPR-Cas, that provide sequence-specific protection against phage infection. In turn, phages have...
Bacteria have evolved sophisticated adaptive immune systems, called CRISPR-Cas, that provide sequence-specific protection against phage infection. In turn, phages have evolved a broad spectrum of anti-CRISPRs that suppress these immune systems. Here we report structures of anti-CRISPR protein IF9 (AcrIF9) in complex with the type I-F CRISPR RNA-guided surveillance complex (Csy). In addition to sterically blocking the hybridization of complementary dsDNA to the CRISPR RNA, our results show that AcrIF9 binding also promotes non-sequence-specific engagement with dsDNA, potentially sequestering the complex from target DNA. These findings highlight the versatility of anti-CRISPR mechanisms utilized by phages to suppress CRISPR-mediated immune systems.
Topics: Amino Acid Sequence; Bacteria; Bacterial Proteins; Bacteriophages; CRISPR-Cas Systems; Cryoelectron Microscopy; DNA; Models, Molecular; Multiprotein Complexes; Nucleic Acid Conformation; Protein Binding; Protein Conformation; Proteus penneri; RNA, Guide, CRISPR-Cas Systems; Sequence Homology, Amino Acid; Viral Proteins
PubMed: 32483187
DOI: 10.1038/s41467-020-16512-1