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Nat Microbiol. 2017 Oct;2(10):1374-1380. doi: 10.1038/s41564-017-0004-7. Epub 2017 Aug 7.

An anti-CRISPR from a virulent streptococcal phage inhibits Streptococcus pyogenes Cas9.

Author information

1
Département de biochimie, de microbiologie, et de bioinformatique, Faculté des sciences et de génie, Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec City, QC, G1V 0A6, Canada.
2
DuPont Nutrition and Health, BP 10, 86220, Dangé-Saint-Romain, France.
3
DuPont Nutrition and Health, 3329 Agriculture Dr, Madison, WI, 53716, USA.
4
Département de biochimie, de microbiologie, et de bioinformatique, Faculté des sciences et de génie, Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec City, QC, G1V 0A6, Canada. Sylvain.Moineau@bcm.ulaval.ca.
5
Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de médecine dentaire, Université Laval, Québec City, QC, G1V 0A6, Canada. Sylvain.Moineau@bcm.ulaval.ca.

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 1 . This evasion can be due to point mutations 1 , large-scale deletions 2 , DNA modifications 3 , or phage-encoded proteins that interfere with the CRISPR-Cas system, known as anti-CRISPRs (Acrs) 4 . The latter are of biotechnological interest, as Acrs can serve as off switches for CRISPR-based genome editing 5 . Every Acr characterized to date originated from temperate phages, genomic islands, or prophages 4-8 , 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.

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PMID:
28785032
DOI:
10.1038/s41564-017-0004-7
[Indexed for MEDLINE]

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