Bacteriophage genes that inactivate the CRISPR/Cas bacterial immune system

Nature. 2013 Jan 17;493(7432):429-32. doi: 10.1038/nature11723. Epub 2012 Dec 16.


A widespread system used by bacteria for protection against potentially dangerous foreign DNA molecules consists of the clustered regularly interspaced short palindromic repeats (CRISPR) coupled with cas (CRISPR-associated) genes. Similar to RNA interference in eukaryotes, these CRISPR/Cas systems use small RNAs for sequence-specific detection and neutralization of invading genomes. Here we describe the first examples of genes that mediate the inhibition of a CRISPR/Cas system. Five distinct 'anti-CRISPR' genes were found in the genomes of bacteriophages infecting Pseudomonas aeruginosa. Mutation of the anti-CRISPR gene of a phage rendered it unable to infect bacteria with a functional CRISPR/Cas system, and the addition of the same gene to the genome of a CRISPR/Cas-targeted phage allowed it to evade the CRISPR/Cas system. Phage-encoded anti-CRISPR genes may represent a widespread mechanism for phages to overcome the highly prevalent CRISPR/Cas systems. The existence of anti-CRISPR genes presents new avenues for the elucidation of CRISPR/Cas functional mechanisms and provides new insight into the co-evolution of phages and bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriophages / genetics*
  • Biological Evolution
  • Gene Expression Regulation, Viral
  • Genes, Bacterial / genetics*
  • Genes, Viral / genetics*
  • Genome, Viral / genetics
  • Inverted Repeat Sequences / genetics*
  • Molecular Sequence Data
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / immunology*
  • Pseudomonas aeruginosa / virology*

Associated data

  • GENBANK/JX434030
  • GENBANK/JX434031
  • GENBANK/JX434032
  • GENBANK/JX434033