A Type I-F Anti-CRISPR Protein Inhibits the CRISPR-Cas Surveillance Complex by ADP-Ribosylation

Mol Cell. 2020 Nov 5;80(3):512-524.e5. doi: 10.1016/j.molcel.2020.09.015. Epub 2020 Oct 12.

Abstract

CRISPR-Cas systems are bacterial anti-viral systems, and phages use anti-CRISPR proteins (Acrs) to inactivate these systems. Here, we report a novel mechanism by which AcrIF11 inhibits the type I-F CRISPR system. Our structural and biochemical studies demonstrate that AcrIF11 functions as a novel mono-ADP-ribosyltransferase (mART) to modify N250 of the Cas8f subunit, a residue required for recognition of the protospacer-adjacent motif, within the crRNA-guided surveillance (Csy) complex from Pseudomonas aeruginosa. The AcrIF11-mediated ADP-ribosylation of the Csy complex results in complete loss of its double-stranded DNA (dsDNA) binding activity. Biochemical studies show that AcrIF11 requires, besides Cas8f, the Cas7.6f subunit for binding to and modifying the Csy complex. Our study not only reveals an unprecedented mechanism of type I CRISPR-Cas inhibition and the evolutionary arms race between phages and bacteria but also suggests an approach for designing highly potent regulatory tools in the future applications of type I CRISPR-Cas systems.

Keywords: ADP-ribosylation; AcrIF11; anti-CRISPR protein; type I-F CRISPR-Cas system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation / physiology
  • Bacterial Proteins / genetics
  • Bacteriophages / genetics
  • CRISPR-Associated Proteins / antagonists & inhibitors*
  • CRISPR-Associated Proteins / genetics
  • CRISPR-Associated Proteins / metabolism
  • CRISPR-Cas Systems / genetics
  • CRISPR-Cas Systems / physiology*
  • Clustered Regularly Interspaced Short Palindromic Repeats / genetics
  • Cryoelectron Microscopy / methods
  • DNA / metabolism
  • Models, Molecular
  • RNA, Bacterial / metabolism
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*

Substances

  • Bacterial Proteins
  • CRISPR-Associated Proteins
  • RNA, Bacterial
  • Viral Proteins
  • DNA