PMID:28785032

Citation	Hynes, AP, Rousseau, GM, Lemay, ML, Horvath, P, Romero, DA, Fremaux, C and Moineau, S (2017) An anti-CRISPR from a virulent streptococcal phage inhibits Streptococcus pyogenes Cas9. Nat Microbiol 2:1374-1380
Abstract	The CRISPR-Cas system owes its utility as a genome-editing tool to its origin as a prokaryotic immune system. The first demonstration of its activity against bacterial viruses (phages) is also the first record of phages evading that immunity . This evasion can be due to point mutations , large-scale deletions , DNA modifications , or phage-encoded proteins that interfere with the CRISPR-Cas system, known as anti-CRISPRs (Acrs) . The latter are of biotechnological interest, as Acrs can serve as off switches for CRISPR-based genome editing . Every Acr characterized to date originated from temperate phages, genomic islands, or prophages , and shared properties with the first Acr discovered. Here, with a phage-oriented approach, we have identified an unrelated Acr in a virulent phage of Streptococcus thermophilus. In challenging a S. thermophilus strain CRISPR-immunized against a set of virulent phages, we found one that evaded the CRISPR-encoded immunity >40,000× more often than the others. Through systematic cloning of its genes, we identified an Acr solely responsible for the abolished immunity. We extended our findings by demonstrating activity in another S. thermophilus strain, against unrelated phages, and in another bacterial genus immunized using the heterologous SpCas9 system favoured for genome editing. This Acr completely abolishes SpCas9-mediated immunity in our assays.
Links	PubMed Online version:10.1038/s41564-017-0004-7
Keywords	Bacterial Proteins/drug effects; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; CRISPR-Cas Systems/drug effects; Cloning, Molecular; Clustered Regularly Interspaced Short Palindromic Repeats/drug effects; DNA, Bacterial; Escherichia coli/genetics; Escherichia coli/immunology; Escherichia coli/virology; Gene Editing; Genomic Islands/genetics; Immunity; Lactococcus lactis/genetics; Lactococcus lactis/metabolism; Phenotype; Point Mutation; Prophages; Streptococcus Phages/genetics; Streptococcus Phages/metabolism; Streptococcus pyogenes/drug effects; Streptococcus pyogenes/immunology; Streptococcus pyogenes/virology; Streptococcus thermophilus/genetics; Streptococcus thermophilus/virology; Transformation, Bacterial; Viral Proteins/genetics; Viral Proteins/immunology; Viral Proteins/pharmacology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
9CAUD:A0A220GHA5		GO:0098672: evasion by virus of CRISPR-cas system	ECO:0007040:		P		Figure 2b shows how the activity of an Anti-CRISPR protein (acrIIA5) with A CR1 immune cell in a Streptococcus phage (D4276) can increase sensitivity to cos-type phage D5842	complete CACAO 13537

References

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