AcrIF9 tethers non-sequence specific dsDNA to the CRISPR RNA-guided surveillance complex

Nat Commun. 2020 Jun 1;11(1):2730. doi: 10.1038/s41467-020-16512-1.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacteria / genetics
  • Bacteria / metabolism*
  • Bacteria / virology
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Bacteriophages / genetics
  • Bacteriophages / metabolism*
  • CRISPR-Cas Systems*
  • Cryoelectron Microscopy
  • DNA / chemistry
  • DNA / genetics
  • DNA / metabolism*
  • Models, Molecular
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism
  • Multiprotein Complexes / ultrastructure
  • Nucleic Acid Conformation
  • Protein Binding
  • Protein Conformation
  • Proteus penneri / genetics
  • Proteus penneri / metabolism
  • Proteus penneri / virology
  • RNA, Guide / chemistry
  • RNA, Guide / genetics
  • RNA, Guide / metabolism*
  • Sequence Homology, Amino Acid
  • Viral Proteins / chemistry
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*

Substances

  • Bacterial Proteins
  • Multiprotein Complexes
  • RNA, Guide
  • Viral Proteins
  • DNA