Inhibition of CRISPR-Cas9 ribonucleoprotein complex assembly by anti-CRISPR AcrIIC2.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31243272.
- Also identified by DOI 10.1038/s41467-019-10577-3 and PMC identifier 6594998.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
CRISPR-Cas adaptive immune systems function to protect bacteria from invasion by foreign genetic elements. The CRISPR-Cas9 system has been widely adopted as a powerful genome-editing tool, and phage-encoded inhibitors, known as anti-CRISPRs, offer a means of regulating its activity. Here, we report the crystal structures of anti-CRISPR protein AcrIIC2<sub>Nme</sub> alone and in complex with Nme1Cas9. We demonstrate that AcrIIC2<sub>Nme</sub> inhibits Cas9 through interactions with the positively charged bridge helix, thereby preventing sgRNA loading. In vivo phage plaque assays and in vitro DNA cleavage assays show that AcrIIC2<sub>Nme</sub> mediates its activity through a large electronegative surface. This work shows that anti-CRISPR activity can be mediated through the inhibition of Cas9 complex assembly.
Medical subject headings
- Bacteriophages
- CRISPR-Associated Protein 9
- CRISPR-Cas Systems
- Ribonucleoproteins
- Viral Proteins